Industrial control technology – Page 10

Posted on 2024年7月15日2024年7月15日 by baiyuzhan — Leave a comment

Analysis of 3 types of VFD motherboard wiring terminal signal source drawings

If you frequently repair a certain brand or several brands of inverters, you should have the terminal diagram of the connection cable between the CPU motherboard and the power/driver board. With it, the maintenance efficiency will be greatly improved. I spent a lot of effort to survey and map the terminal diagrams of the CPU motherboards of three inverters. I dare not keep it secret, so I share it here with you.

The above figure shows the function/destination (50 lines) of the TECO 7300PA inverter mainboard wiring terminal 7CN. The inverter of this model has excellent versatility in CPU mainboards, ranging from 22kW to 300kW, and can be interchanged. You only need to adjust the parameter “inverter capacity”. That is to say, this brand of inverter, due to different power levels, except for the power supply/driver board, actually uses the same CPU mainboard, so this terminal diagram can be used for “all sizes” during maintenance.

Figure 1.Function/direction diagram of TECO 7300PA inverter mainboard wiring terminal 7CN

Using the terminal diagram:

1. Check the input and output control signals. Most of them are switch signals, and the high and low level values are very obvious. For example, the detection signal terminals 2 and 4 of the charging contactor and temperature sensor have a terminal voltage of 24V when normal and 0V when abnormal. The static and dynamic (start/stop) voltage values of the six-way pulse signal terminals are obvious; although the output current detection signal is an analog quantity, it should be 0V when static and unloaded. Generally, it is about 2V when fully loaded.

2. You can “play tricks” on the terminals. For example, if the module overheats, you can try to short-circuit terminal 4 and pin 28. If the fault disappears, it means that the external temperature relay (sensor) at terminal 2 is faulty. If the fault still exists, it means that the fault is in the subsequent temperature signal processing circuit.

If you connect a potentiometer between terminals 10 and 29 and connect its center arm to the output current detection terminal (terminal 7 or 9), you can simulate a load test to check whether the subsequent current detection circuit is normal.

If an analog signal only deviates from the normal value (and still works), and falsely reports an “overvoltage” fault under normal power supply, you can use parallel and series resistance methods at terminals 23 to make its voltage value fall back to the normal detection value for emergency repair.

[ Failure Example 1 ] :

A 300kW7300PA inverter has an output frequency display on the operation display panel, but there is no three-phase voltage output on the U, V, and W terminals. After disconnecting the power supply of the inverter circuit, the six pulse signals of the 11, 13, 15, 17, 19, and 21 pins of the 7CN terminal were measured and all were normal. It was determined that the fault was in the pulse pre-stage signal circuit of the power supply/driver board. From these six terminals, it was quickly found that U12 (MC14069) was defective. After replacement, the fault was eliminated.

[ Failure Example 2 ] :

A 300kW7300PA inverter reported a “DC circuit undervoltage” fault after power-on and could not start running. The DC circuit voltage detection signal of terminal 23 of the wiring terminal 7CN was normal. After power-on, the measurement of terminal 2 was always low level, indicating that the auxiliary contact of the charging contactor was not closed. The CPU detected that the charging contactor was not closed, so it reported an undervoltage fault.

Try to short-circuit terminal 2 and terminal 28, and it runs normally.

Check from terminal 2 to the power supply/driver board and find out that the normally open contact of relay KA1 is connected in series in the 2-terminal circuit. The contact of KA1 is in poor contact. Replace KA1 and the fault is eliminated.

[ Failure Example 3 ] :

A 7300PA37kW inverter reported an OC fault as soon as it was powered on. The power supply of the current detection circuit was detected from the terminals. The -15V of terminals 40, 41, and 42 was 0V. Due to the abnormal power supply, the output of the current detection circuit was offset and an OC fault was reported. The -15V rectifier diode of the switching power supply was checked and found to be open. The fault was eliminated after replacement.

In the above three faults, with the guidance of the 7CN terminal diagram, the faults were found quickly and accurately in a very short time and the faults were eliminated efficiently.

Figure 2.Alpha ALPHA2000 medium and small power inverter CNM motherboard wiring terminal function/direction diagram

The above picture is the Alpha inverter CPU motherboard CNM wiring terminal diagram, a total of 24 lines. Although the CPU motherboard of this model cannot be replaced – the overload protection and other parameters are fixed and the relevant parameter values cannot be modified; the CPU motherboard circuits are also different. I have seen two motherboard circuits, but the CNM terminals are the same. Therefore, the CNM terminal function/destination diagram is still very valuable as a “guide” for maintenance.

[ Failure Example 1 ] :

An Alpha 2000 15kW inverter tripped an undervoltage fault as soon as it was started, and no charging contactor closure sound was heard when it was powered on. The CNM terminal 1 was tested and was always at a high level of 24V, indicating that the charging relay control circuit was faulty. From terminal 1 to the CPU mainboard, it was determined that the circuit inside the CPU control pin was damaged.

Emergency repair: Short-circuit terminal 1 and terminal 7. After the switching power supply starts to oscillate, force the charging relay to be energized and closed to eliminate the fault.

[ Failure Example 2 ] :

An Alpha 2000 18.5kW inverter, with a load rate of less than 50%, but the on-site power supply fluctuates greatly, sometimes as low as 320V. The inverter tripped an undervoltage fault, and the dealer and the user required measures to make the inverter run. Cut the cable of CNM terminal 8, connect a 4.7kΩ semi-variable resistor between terminals 25 and 7 , connect the center arm to terminal 8, and adjust it to a fixed voltage of 3V.

The inverter no longer trips the undervoltage fault and operates normally. (This emergency measure must be used with caution in specific applications!)

Figure 3.Function/direction diagram of CN1 terminal on INVT G9/P9 medium power inverter motherboard

There is a trick to speed up the inspection, which is to make a diagram of the motherboard wiring terminals. Clearly mark the terminal serial number and the source and destination of the terminal signal. It would be even better if the dynamic and static voltage values of each terminal could be marked. Fortunately, there are many switching signals, which are easier to detect and judge. Analog signals also have obvious differences in dynamic and static, which are easier to detect.

The figure above is the function/destination diagram of the CN1 terminal. For terminals 4, 7, 8, and 9, the terminals are set by the manufacturer. Except for replacing the CPU motherboard, you can check the short-circuited state of the terminals. For maintenance, it is useless, so don’t worry about it. 24V, +15, -15V, +15V, and +5V power supplies are the 5 power supplies commonly used by the CPU motherboard. Some inverters have two 24V power supplies, one for the control relay coil and the other for the control sub-power supply. The power supply introduction in the terminal occupies most of the terminals, six inverter pulses, and some have one DC braking pulse, which occupies part of the terminals. The others are various input/output, switch quantity/analog quantity signal terminals. What we need to pay attention to and frequently test is this third type of terminal. When checking a certain circuit, you can also artificially change the voltage state of this type of terminal to see if the corresponding circuit reacts. By observing or measuring the normal or abnormal reaction of the corresponding circuit, you can clearly judge whether the circuit is good or bad.

[ Failure Example 1 ] :

An INVT G9/P9 5.5kW inverter has an unbalanced output three-phase voltage. After disconnecting the inverter power supply, the start signal is input and the six pulse signal terminals 19, 21, 23, 25, 27 and 29 of CN1 are detected. It is found that the voltage at pin 21 is fixed and there is no change in dynamic or static state. It is judged that the fault is in the pulse pre-stage circuit or the PWM pulse output pin of the CPU.

Check the inverter pulse pre-stage circuit U4 (LS07), the six-way inverter pulse at the input end is normal, and there is no signal voltage output at the output pin 8. Replace U4 and the fault is eliminated.

[ Failure Example 2 ] :

An INVT G9/P9 5.5kW inverter reported an undervoltage fault during operation. The CN1 terminal 39 pin was detected to be low level, indicating that the CPU has output a charging relay closing signal. The charging relay was checked and found to have been replaced. The coil solder joints were poorly soldered. After re-welding, the fault was eliminated.

Posted on 2024年6月6日2024年6月6日 by baiyuzhan — Leave a comment

Based on the overall circuit of the VFD (Variable Frequency Drive), there are two malfunctions.

(A) Power Supply Fault Inspection:

Fault Status: After powering on, the entire device does not respond, and the operation display panel shows no display. The measured 24V and 10V control power at the control terminals are both 0V.

Fault Essence: The VFD’s switching power supply is not working.

Troubleshooting Approach: (1) Switching voltage fault; (2) Pre-charging circuit fault.

Troubleshooting Method:
(1) First check the power supply source of the switching power supply and whether the DC loop has a normal 530V voltage. If the DC loop voltage is 0V, it indicates a fault in the pre-charging circuit, such as an open charging resistor, damaged half-wave rectifier circuit, or poor contact of the normally closed contact of the contactor or relay. Repair the pre-charging circuit first and then check the fault of the switching power supply. Often, after repairing the pre-charging circuit, the VFD is also repaired. It is not necessary to focus too much on the switching power supply circuit at first.

(2) If the 530V, 265V, or 300V DC power supply for the switching power supply is available, do not focus too much on its voltage stabilization and oscillation circuit. First, check if there are any faults such as short circuits in the secondary load circuit of the switching transformer, such as a damaged cooling fan, an IC short circuit in the fault detection circuit, or a breakdown of the rectifier diode. The fault rate on the load side of the switching power supply is higher, while the problems in the oscillation and voltage stabilization links are less common.

The troubleshooting approach and order determine the efficiency of the repair work. From the perspective of the entire circuit, checking the pre-charging circuit is a very important step and should be the first consideration when troubleshooting the fault of a non-working switching power supply.

(B) Fault Inspection of the Inverter Pulse Circuit:

The section from the six PWM output terminals of the CPU to the intermediate buffer circuit is called the pre-stage circuit of the inverter pulse, while the drive circuit is referred to as the post-stage circuit of the inverter pulse, collectively known as the inverter pulse circuit.

Fault Conditions:

(1) Normal start-up operation, with normal output frequency indication on the operation display panel, but no three-phase output voltage.
(2) Normal start-up operation, with normal output frequency indication on the operation display panel, but unbalanced three-phase output voltage.
(3) OC fault occurs immediately after pressing the start button.
(4) OC fault occurs during operation.
(5) Light-load operation is normal, but motor with load jumps or encounters OC fault.

Essence of the Faults and Inspection Approach (Corresponding to the Five Fault Conditions):

(1) Several factors may contribute: a. Loss of +5V* power supply on the input side of the drive circuit’s optical coupler; b. Damage to the buffer of the pre-stage pulse circuit; c. Uncertainty of the CPU’s relevant control signals or damage to related control pins; d. Misoperation of the fault protection circuit, resulting in the locking of the pulse pre-stage circuit by the fault signal.

Special attention should be paid to the pre-stage circuit of the inverter pulse signal, such as tri-state triggers and buffer circuits, which may be directly controlled by voltage and current detection and protection circuits. When the protection circuit misoperates, it may clamp and block the transmission of six pulse signals. The concept of the fault protection circuit participating independently in pulse transmission control should be kept in mind. Although faults caused by a and b are more common, those caused by c and d often constitute difficult faults, and a lack of inspection approach in this regard may lead to detours in repair.

(2) Three factors may contribute: a. Damage to the opto-coupler of the drive circuit, preventing the normal transmission of inverter pulse signals; b. Increased internal resistance of the inverter module, leading to poor conduction in three upper-arm IGBT modules. Therefore, the three drive circuits may not be equipped with IGBT voltage drop detection circuits, resulting in a failure to report OC faults; c. Malfunction of the pre-stage pulse circuit or the CPU inverter pulse output pin, causing the inverter pulse to be missing in one or two channels.

Don’t focus solely on the post-stage drive circuit, as the inverter pulse of the pre-stage may not be input to the drive circuit. Especially, consider whether the module is faulty or the internal resistance of the inverter module has increased. Failing to consider factor c may also lead to difficult faults.

(3) Several factors may contribute: a. Defects in the post-stage drive circuit itself; b. Insufficient load capacity of the power supply of the drive circuit, such as loss of capacitance in filter capacitors and low efficiency of rectifying diodes (increased forward resistance and decreased reverse resistance); c. Defects in the inverter module.

Dynamic and static testing (voltage testing) of the drive circuit may appear normal, but it is necessary to test the current output capability of the drive circuit. Pay attention to factors b and c.

(4) Several factors may contribute: a. Load capacity of the drive circuit and internal resistance detection of the inverter module; b. Three-phase output current detection circuit; c. Reference voltage circuit in the fault detection circuit; d. User load-related reasons.

Pay attention to the influence of factors b, c, and d. Defects in the three-phase detection circuit itself or shifts in the operating point may cause false OC fault reports. Deviations in the reference voltage of the fault detection circuit may lead to inaccurate current detection and false OC fault reports. If all checks are fine, look for the cause on the production site, not excluding issues related to the load. Factors b and c may again fall into the category of difficult faults.

(5) Three factors may contribute: a. Insufficient current (power) output capability of the drive circuit; b. Defects in the inverter module, resulting in increased internal resistance; c. Issues with the load circuit, such as a faulty motor, not necessarily a fault of the VFD.

Abnormal operation of the VFD does not necessarily indicate a problem with the VFD itself. It is recommended that users try replacing the motor. Consider factors b and c, and sometimes factors outside the VFD.

Posted on 2024年6月3日2024年6月3日 by baiyuzhan — Leave a comment

Analog circuits used in VFD fault detection circuits

The main circuit of the fault detection circuit is still composed of an operational amplifier. Usually, the operational amplifier is connected to the following types of circuits, completing three tasks of signal analog amplification, comparative output, and precision rectification.
(A)、 Inverting amplifier circuit:

Operational amplifier reverse amplification circuit

An operational amplifier has excellent characteristics such as high input impedance (without using signal source current), low impedance (with good load characteristics), amplification of differential mode signals (the difference between two input signals), suppression of common mode signals (with the same polarity and size of the two input terminals), and the ability to provide linear amplification for both AC and DC signals.
The figures (1), (2), and (3) in the circuit form are inverting amplifiers, where the output signal is in opposite phase to the input signal, also known as inverting amplifiers. The circuit has a dual amplification effect of voltage and current on the input voltage signal, but in small signal circuits, only the amplification and processing of the voltage signal are emphasized. The voltage amplification factor of a circuit depends on the ratio of R2 (feedback resistance) to R1 (input resistance). R3 is the bias resistor, and its value is the parallel value of R1 and R2. Due to the different values (ratios) of R2 and R1, three types of signal transmission functions can be completed, namely, forming three signal processing circuits: inverter amplifier, inverter, and attenuator. (1) The circuit is an inverting amplifier circuit with an amplification factor of 5; (2) The circuit is a inverter, which plays a reverse phase output role on the input signal and has no amplification factor, so it cannot be called an amplifier. Or input a 0-5V signal, then output a 0-5V inverted phase signal; (3) The circuit is an attenuator circuit. If a 0-10V signal is input, the output is 0-3. A 3V inverted signal is a proportional attenuator.
Figures (1), (2), and (3) have two characteristics of the circuit: 1. The input and output signals are reversed; 2. Whether it is an amplification, attenuation, or inverting circuit, the output signal maintains a proportional output relationship with the input signal, which can be broadly referred to as an inverting amplifier because the amplification factor of the inverter is 1, and the attenuator precisely utilizes the amplification effect of the circuit.
It is interesting that these three types of inverting amplifiers have applications in current and voltage detection circuits. Taking the current detection circuit as an example: This is because the current transformer connected in series to the three-phase output terminal has an amplifier built-in, and the output signal has reached a voltage amplitude of volts, while the input signal amplitude of the CPU must be within a voltage amplitude of 5V or less. Therefore, some reverse current signal processing circuits use reverse amplifiers with a certain amplification factor; Some use inverter circuits, which only perform inverter processing on the signal based on the polarity requirements of the CPU input voltage signal, without the need for further amplification; Some circuits are adapted to the signal amplitude range of the later stage circuit, and even use attenuator circuits to attenuate the voltage signal from the current transformer before sending it to the later stage circuit.
The power supply of the analog signal circuit in the detection circuit is generally powered by both positive and negative 15V dual power sources according to the requirements of amplifying AC signals. Based on the circuit form of the inverter amplifier and the circuit characteristics of the operational amplifier, we can find the corresponding detection method:

According to the characteristics of the inverting amplifier, when a positive signal voltage is input, the input voltage must be negative below 0V, and vice versa, the output voltage must be positive above 0V, with 0V (ground) as the reference potential. To determine whether it is in a normal state based on the static circuit values of the circuit and input/output pins;
Identify whether the circuit in this stage is an amplifier, inverter, or attenuator. Based on the ratio of input resistance to feedback resistance, the output voltage value can be roughly calculated to determine whether the circuit is in a normal state;
According to the characteristic that the circuit has an amplification (or attenuation) effect on differential mode signals and a zero amplification effect on common mode signals, when short circuiting two input terminals, the output voltage should be close to the zero potential value; Alternatively, if there is a positive voltage (or negative voltage output) at the output terminal, but two input terminals are short circuited, the output voltage immediately drops (or rises) to around 0V. The circuit is good and can transmit signals normally.
If the input voltage value can be artificially changed, the output voltage will inevitably change accordingly, which can be used to determine whether the amplifier is in a normal state.
[Fault Example 1]
After a certain frequency converter is powered on, an OC fault is reported, and the fault reset is invalid. The current detection circuit, as shown in the diagram (1), has an output voltage of+12V. The CPU reports an OC signal after power on due to a serious overcurrent signal input. Short circuit the 2 and 3 pins of the operational amplifier with metal tweezers, measure that there is no change in the output circuit of pin 1, and it is still+12V. It is judged that the operational amplifier is damaged. After replacement, the fault is eliminated.
[Fault Example 2]
A certain frequency converter outputs an undervoltage signal after being powered on, and detects the electrogram (2) circuit. The input voltage is -3V, but the output voltage is 0. 7V, indicating a malfunction of the amplifier in this stage. A 10k resistor was connected in series with an external DC 12V power supply, and the output voltage did not change when input to the reverse input terminal. It was determined that the amplifier in this stage was damaged, and the fault was resolved after replacement.
(B)、 In phase amplifier and voltage follower circuit:

In phase amplification circuit and voltage follower circuit

The circuit shown in Figure (1) is a typical circuit form of a in-phase amplifier, which is also one type of amplifier circuit. The input signal enters the same phase end of the amplifier, and the output signal is in the same phase as the input signal. The voltage amplification factor of the circuit is 1+R2/R1. It is also used for amplifying analog signals in fault signal detection circuits. When R2 is short circuited or R3 is open circuited, the output signal has the same phase and equal magnitude as the input signal, so (1) the circuit can further evolve into (2) and (3) circuits.
The above figures (2) and (3) show the voltage follower circuit. The output voltage completely tracks the amplitude and phase of the input circuit, so the voltage amplification factor is 1. Although there is no voltage amplification effect, it has a certain current output ability. The circuit plays a role in impedance transformation, improving the load capacity of the circuit and reducing the mutual influence of high impedance in the signal input circuit and low impedance in the output circuit. When used as a circuit follower, sometimes a single power supply is also used.
(1) The circuits (2) and (3) are also used in fault detection circuits for amplifying analog signals and processing reference voltage signals.
Based on the characteristics and functions of the circuit, the detection method can be obtained as follows:

(1) The circuit is a in-phase amplifier circuit, and the output voltage amplitude and polarity are proportional to the input voltage. The voltage amplification factor of this stage is about 6 times. When the input voltage value is 1V, the output voltage is approximately 6V. It is possible to determine whether the circuit is in a normal state based on the calculation of input and output voltage values;
(2) (3) The circuits are all voltage follower circuits, and the output voltage is completely tracked by the input voltage. The output voltage should be equal to the input voltage, which can be used to determine whether the circuit is in a normal state.
By short circuiting two input terminals or manually changing the input voltage, the corresponding changes in the output voltage can be measured to determine whether the circuit is in a normal state.
[Fault Example 1]
A certain frequency converter experienced an OH fault when powered on. The reference voltage circuit of the temperature detection circuit, as shown in Figure (2), has an output voltage of 1V. This machine is a voltage comparator circuit, and its input voltage is measured to be 5V. Under normal conditions, the output voltage should also be 5V. After cutting off the output load circuit, the output voltage remains at 1. 2V, it was determined that the amplifier in this stage was damaged, and the fault was resolved after replacement.
(C) Precision positive and negative half wave rectifier and full wave rectifier circuits:

Precision half wave and full wave rectifier circuits

The AC voltage signal from the current transformer needs to be rectified into DC voltage through subsequent half wave or full wave rectification circuits, and then sent to the CPU for current display and control. Precision half wave or full wave rectification circuits are also used for processing and amplifying analog signals. Ordinary rectification circuits use diodes as rectification devices, but diode rectification has drawbacks such as nonlinear distortion and dead zone voltage. Especially when used for small signal rectification, it will cause output signal distortion and output errors. By utilizing the amplification effect and deep negative feedback effect of the operational amplifier, a diode is added to the amplification circuit. By utilizing the unidirectional conductivity characteristics of the diode, different depths of negative feedback are introduced to the input positive and negative half wave signals. The input μ V level signal can be rectified in a dense manner, and the circuit itself also has a voltage following or amplification effect.
The above figure (2) shows a precision negative half wave rectification circuit. The circuit will perform precision rectification on the input negative half wave signal and output it in reverse phase. For the positive half wave input signal, the connection of D1 introduces deep negative feedback to the amplifier; At the beginning of the negative half wave input signal, due to the signal input amplitude being smaller than D1 and D2, both are in the cut-off state, and the circuit is in an open-loop amplification state. A small signal input will cause the output pin voltage to be greater than -0. 7V, D1 conduction, D2 reverse bias cutoff; The series connection of D2 and R125 introduces moderate negative feedback (the resistance of R125 can determine whether the current circuit is a rectifier or a rectifier amplifier, and the current circuit is a precision rectifier with no amplification effect), which is equivalent to an inverter amplifier, and the output is inversely correlated with the input signal.
The difference between the circuit in Figure (1) and Figure (2) is that the polarity of the two diodes in the circuit is opposite, making it a precise rectification circuit for the input positive half wave signal. The principle of rectification is the same.
By adding a half wave rectifier circuit and an inverse summation circuit, as shown in Figure (3), the positive and negative half waves are input and output in reverse to obtain a full wave output voltage waveform, forming a high-precision full wave rectifier circuit.
In fault detection circuits, rectifier circuits are often used to sample the three-phase output current signal, which is rectified and amplified as an analog voltage signal (current detection signal) input into the subsequent fault signal processing circuit and CPU circuit, used for overload alarm and sampling processing of operating current.
The input of the circuit is an AC voltage signal, while the output is a DC voltage signal. Most circuits are rectifiers, and some circuits are rectifier amplifiers.
Detection method:

Rectifier circuit: The input side is AC voltage, and the output side is DC voltage. The two measured values are relatively close.
Rectifier amplifier, with AC voltage on the input side and DC voltage on the output side. The output DC voltage value is higher than the input AC voltage value.
By short circuiting two input terminals or manually changing the input voltage, the corresponding changes in the output voltage can be measured to determine whether the circuit is in a normal state.
[Fault Example 1]
A certain frequency converter experienced an OC fault when powered on. The output voltage of the current detection circuit as shown in Figure (2) was 13V. After unplugging the lead terminal of the current transformer, the amplifier in that stage still had 13V. It was determined that the rectifier circuit was damaged and the fault was resolved after replacement.
(C) Circuit for voltage comparator, step voltage comparator, and window voltage comparator:
The above-mentioned circuits are all used for amplifying and rectifying analog signals, and their output signals still have analog signals, which can be called analog signal (amplification) processing circuits. However, in the following voltage comparison and other circuits, the output is a switch signal. The circuit has left the scope of analog amplification and seems to have entered the field of “digital circuits”, using analog circuits as digital circuits for application.

Three types of voltage comparator circuits

The function of a voltage comparator is to compare the magnitude of two input voltage signals. In Figure (1) of the circuit, the voltage at the same phase input end of the amplifier is the voltage divider value 2 of R2 and R3 resistors to+5V. 5V, known as the reference voltage value, compares the input signal with this reference value. When it is higher than this value, it outputs a 0V low-level signal. When it is lower than the low value, it outputs a+15V high-level signal. Circuit, also known as a single value comparator, the output state of the circuit depends on a value (a point) of the input signal voltage -2. 5V.
If the two-stage voltage comparator is connected to the circuit shown in Figure (2), it becomes a stepped voltage comparator. The circuit has one input signal and two output signals. The N1 and N2 voltage comparators input the same signal voltage, but the reference voltage values at the same phase input terminals of the two-stage circuit are different. The N1 reference voltage is 6. The reference voltage value for 6V and N2 is 3. 3V. When the input signal gradually increases from 0V to 3. When the voltage is above 3V, the output state of N2 first changes to low level; N2 has an input signal value greater than 6. At 6V, there is only a low-level signal output. When the circuit in Figure (2) is used for voltage detection in the DC circuit, when the regenerative energy generated by the load motor is fed back to the DC circuit, causing the DC circuit voltage to rise to a certain value, N2 first outputs a braking action signal, connects the braking resistor to the DC circuit, and consumes the voltage increment; If the voltage continues to rise, N1 will output an OU overvoltage signal, and the frequency converter will shut down for protection.
If the two-stage voltage comparator is connected to the circuit shown in Figure (3), it constitutes a window voltage comparator circuit. Compared to single-stage voltage comparator circuits, window voltage comparators can be referred to as dual value comparators. The circuit has two benchmark comparison values and outputs one signal. When the input signal is ≥ reference voltage 1 ≤ reference voltage 2, the circuit output state transitions. Within a range of the intermediate value of the input signal, the output state remains unchanged. The circuit in Figure (3) is a ground fault signal processing circuit. The in-phase end of the N1 amplifier is the voltage divider of R46 and R50 to+15V, while the reverse end of the N2 amplifier is the voltage divider of R81 and R69 to -15V. The input three-phase current sampling signal enters the reverse input terminal of N1 and the in-phase input terminal of N2, and is compared with the positive and negative partial voltage values, respectively. Whether it is the positive half wave or negative half wave of the input signal, as long as it is greater than the two reference values, a ground short circuit signal will be reported.
The voltage comparator uses digital circuits, which can flexibly set the reference voltage based on the signal amplitude, making it more convenient than using digital circuits. In addition, the circuit in Figure (3) adopts an operational amplifier circuit with an open collector output, which can achieve parallel output at the output end, making the circuit more concise. If a regular amplifier is used, the output signal also needs to be isolated by two diodes and connected together in parallel.
Three types of voltage comparator circuits are commonly used to convert analog signals of detected current or voltage into switch signal – fault signal output, for implementing control actions and shutdown protection.
Detection method:

The amplifier output has only two level states, low level, close to the ground level of the power supply or negative power supply value; High level, close to positive power supply value;
If the voltage value of the inverting input terminal is lower than that of the in-phase input terminal, the output is low level; otherwise, the output is high level.
By short circuiting two input terminals or manually changing the input voltage, the corresponding changes in the high and low levels of the output terminals can be measured to determine whether the circuit is in a normal state.
(E) Hysteresis comparator circuit:
It is also one of the voltage comparator circuits. The circuit in Figure (3) of the voltage comparator, also known as the hysteresis voltage comparator circuit. The voltage comparator circuit can be upgraded to a hysteresis comparator circuit by introducing an additional positive feedback circuit. Hysteresis comparator circuits are referred to as voltage comparator circuits with hysteresis characteristics. If ordinary voltage comparison is regarded as “voltage point comparison”, hysteresis comparator can be regarded as a comparator circuit for “voltage range comparison”. Usually, we hope that the output state of the circuit is stable enough, and comparing the voltage at a “point” can cause instability in the output state due to frequent output. Improving the “point” comparison of the input circuit to “segment” comparison can effectively solve this problem – within a “segment value” of input voltage variation, the output state remains unchanged. Figure (2) shows a positive feedback branch composed of R4 and D1, which converts the “point” comparison characteristic of the circuit into a “segment” comparison characteristic.

The control principle is briefly described as follows:
Assuming that the circuit in Figure (2) is used for processing the braking action signal, the input signal is the voltage sampling signal of the DC circuit. When the voltage of the DC circuit rises abnormally due to the energy feedback from the load motor, reaching 680V, the input voltage value of Vin reaches 9. When the voltage is above 5V and higher than the reference voltage at the reverse end of the amplifier, the amplifier outputs a low-level signal, and the subsequent braking circuit acts, connecting the braking resistor to the DC circuit to consume the voltage increment; Due to the consumption effect of the braking resistor, the input voltage value of Vin quickly drops to 9. Below 5V, but the braking signal is still being output, and it does not mean that the DC circuit voltage slightly drops, causing the braking signal to disappear. This indicates the role of the hysteresis comparator. The braking circuit continues to operate until the DC circuit voltage returns to below 620V, and the sampled input voltage is below 7. The braking circuit only stops working at 5V.
When the circuit is static, the voltage at the same phase end of the amplifier (7.5V) is higher than the voltage at the opposite phase end, and the output voltage is a high-level voltage of nearly 15V. R4 and D1 are introduced into the same phase end circuit, artificially raising the same phase end voltage to 9. 5V. When the input voltage is above 9. At 5V, the circuit output state reverses and the output end becomes low level. D1 reverse bias cutoff, feedback loop interruption, and reference voltage at the same phase end restored to 7. 5 V partial voltage value. In this way, when the input sampling voltage is below 7. At 5 V, the brake signal stops outputting.
Hysteresis comparator circuits are commonly used for voltage detection in DC circuits, outputting braking signals and overvoltage/undervoltage fault signals.
The detection method is the same as the voltage comparator, omitted.

Posted on 2024年6月1日2024年6月1日 by baiyuzhan — Leave a comment

How to conduct load testing on VFD drive circuits to solve the problem of normal no-load and load failure?

The voltage amplitude of the six driving pulses outputted by the driving circuit meets the requirements. For example, measuring the amplitude of the positive excitation pulse voltage in the AC range is about 14V, and the amplitude of the negative cutoff voltage is about 7.5V (different models may vary). After the above inspection of the driving circuit, most maintenance personnel believe that the machine can be installed, but an extremely important inspection step – the inspection of the current (power) output ability of the driving circuit! Many VFDs that we believe have been repaired normally will still expose more hidden faults during operation, leading to a certain repair rate.

VFD operates normally under no-load or light load, but after carrying a certain load, it may experience motor vibration, output voltage phase deviation, frequency jump OC faults, etc.
Cause of malfunction: A. Insufficient output capacity of the power supply current (power) of the driving circuit; B、 The driving IC or the post amplifier of the driving IC is inefficient, and the output internal resistance increases, resulting in insufficient voltage or current amplitude of the driving pulse; C. IGBT is inefficient, with increased internal resistance and increased pressure drop in the conduction tube.

The proportion of failures caused by reason C is not high, and is limited by the conditions of the maintenance department, such as the inability to provide rated load testing for the frequency converter. But for the hidden faults caused by reasons A and B, we can use the method of increasing the load on the driver to expose them and then repair them, which can reduce the repair rate to the lowest level.
The normal opening of IGBT requires not only sufficient excitation circuit amplitude, such as+12V or above, but also sufficient driving current to ensure its reliable opening, or to ensure its conduction under a certain low internal resistance. The essence of the causes of faults A and B mentioned above is that due to the insufficient power output capability of the driving circuit, although the IGBT can be turned on, it cannot be in a good low conductivity internal resistance state, resulting in output phase deviation, severe motor vibration, and frequency jump OC faults.

Let’s conduct a more in-depth analysis of the control characteristics of IGBT and identify the root cause of the fault.

I. Control characteristics of IGBT:
The common perception is that IGBT devices are voltage-controlled devices, which require a certain level of excitation voltage for gate bias control, without the need to draw excitation current. In low-power circuits, only digital gate circuits can drive MOS-type insulated gate field effect transistors. As an IGBT, the input circuit happens to have the characteristics of a MOS-type insulated gate field effect transistor, and can therefore also be considered a voltage-controlled device. This perception is actually biased. Due to structural and process reasons, a junction capacitance called Cge is formed between the gate and emitter junctions of the IGBT tube, which controls the turn-on and turn-off of the IGBT tube. In fact, the charging and discharging control of Cge is responsible for the control of the turn-on and turn-off of the IGBT tube. The +15V excitation pulse voltage provides a charging current path for Cge, which turns on the IGBT; the -7.5V negative pulse voltage “forcibly pulls out the charged charge” on Cge, which plays a role in rapidly neutralizing the charged charge, and turns off the IGBT.
Assuming that the IGBT tube only controls the on-off switching of a DC circuit with a zero operating frequency, and after the Cge is fully charged at one time, there is almost no need for charging and discharging control, it is reasonable to describe the IGBT tube in this circuit as a voltage control device. However, the problem is that the IGBT tube in the output circuit of the frequency converter operates at a frequency of several kHz, and its gate bias voltage is also a pulse voltage with a frequency of several kHz! On the one hand, for such high-frequency signals, the capacitive impedance exhibited by Cge is relatively small, resulting in a large charging and discharging current. On the other hand, to make the IGBT turn on reliably and quickly (striving to make the tube have a small internal resistance), it is necessary to provide as large a driving current (charging current) as possible within the allowable operating range of the IGBT. For the control of turn-off, it is also the same. It is necessary to provide a low-resistance (ohmic) external discharge circuit to discharge the charge on the gate-emitter junction capacitor very quickly!
As we all know, capacitors are energy storage components that do not consume power themselves, and are called capacitive loads. However, just like the principle of power transmission and distribution lines, in addition to the power supply having to provide reactive current (reactive power) for capacitive components, which increases the power capacity of the power supply, the reactive current inevitably brings losses in line resistance (line loss)! The power loss of the drive circuit mainly concentrates on the gate resistance and the conduction internal resistance of the final amplifier tube. We often see that the output stage of the drive circuit, especially for high-power VFDs, is actually a power amplifier circuit, often consisting of medium-power or even high-power transistors, several watts of gate resistance, and other components, indicating that the drive circuit of IGBT consumes a certain amount of power and needs to output a certain current.
From the above analysis, it can be seen that the IGBT tube used in the VFD output circuit should be a current or power drive device, rather than a pure voltage control device

II. The last testing content before installation:
To minimize the rate of rework, after conducting comprehensive testing on the drive circuit in sections 3 and 4, do not miss the inspection of the drive circuit’s load-bearing capacity.
The method is as follows:

Measurement circuit for driving circuit with load capacity

The above diagram shows the driving circuit of the U-phase upper arm of DVP-1 22kW Delta VFD. The GU and EU in the figure are pulse signal output terminals, which are externally connected to the G and E poles of the IGBT. When repairing the drive board, it has been disconnected from the main circuit. The dashed box represents the external measurement circuit. After powering on the power supply/driver board, in conjunction with start and stop operations, a DC 250mA current range is connected in series at points m and n, and an external measuring resistor of 15 Ω 3W forms a circuit to detect the current output capability of each drive circuit. The starting state is measured, and five output current values are all around 150mA, with one output current only 40mA. The reason for the OC trip after installation and operation is precisely because the driving capability of this drive circuit is greatly insufficient! In the shutdown state, the measured current output capacity of each negative voltage power supply is about 50mA, and the negative voltage power supply capacity is normal.
Connecting RC in series plays a current limiting role, and the principle of its value is to select resistance and power values that are equal to the gate resistance (the parameter value of DR45 in the above figure) to make the detection effect obvious.
After testing the power output capability of the driving circuit, it can be determined that the driving circuit is completely normal. During the testing process of connecting the drive circuit to the main circuit, please first use a low-voltage 24V DC power supply to power the inverter circuit. After testing the drive circuit and inverter circuit to be normal, restore the normal power supply to the inverter circuit. If there is no low-voltage DC power supply at hand, at least two 45W light bulbs or 2A fuse tubes should be connected in series in the inverter power supply circuit. After the machine is tested normally, the original power supply of the inverter circuit should be connected!
The above power on detection of the driving circuit is carried out after disconnecting from the main circuit (IGBT). When the whole machine is connected, the input and input sides of the driving circuit must not be measured. Interference signals may be introduced due to human body induction and meter probes, causing IGBT to be triggered and conduct incorrectly, resulting in module explosion!

The insufficient output capability of the driving circuit is caused by two reasons:
A、 The power supply capacity is insufficient. Under no-load conditions, when we detect the output positive and negative voltages, they often reach the normal amplitude requirements. Even under load (such as after connecting to IGBT), although the instantaneous charging capacity of Cge is insufficient, due to the short charging time, we often cannot measure the low voltage drop of the power supply. Without resistive loads, this hidden fault can hardly be detected! The common fault in the circuit is the loss of capacitance of the filtering capacitor, as shown in DC41 in the figure above. Due to the drying up of the electrolyte inside the electrolytic capacitor during long-term operation, its capacity has decreased from a few hundred microfarads to several tens of microfarads, and even to a few microfarads. In addition, there may be inefficient rectifier tubes, such as an increase in forward resistance, which can also cause insufficient power output capacity;
B、 The internal output circuit of the driving IC is poor, or the internal resistance of the rear amplifiers DQ4 and DQ10 increases due to conduction. If there is no low drop in the power supply voltage after load testing, and the output voltage of T250 is detected to be low, it is a T250 defect. Otherwise, replace components such as DQ4 and DQ10. The phenomenon of increased resistance values such as DR40 and DR45 is relatively rare.
It should be noted that the insufficient positive excitation voltage only manifests as severe motor vibration, output voltage phase deviation, frequent OC faults, and other phenomena. Although it may cause overcurrent in the DC component of the motor winding, it poses a danger to the module structure that cannot be put into operation and the signal will burst. The loss of the negative cutoff voltage (caused by a fault in the negative pressure power supply circuit, which blocks the negative gate bias circuit) indicates that it is normal when powered on. When the start button is pressed, the IGBT inverter module will emit a “pop” sound and immediately burst into failure! Why is this?

III. Hazards of IGBT cut-off negative pressure circuit open circuit:
Except for the damage caused by sudden short circuit of the load during full speed operation, the harm of all faults such as overcurrent, overload, and undervoltage is far less than the harm of open circuit of gate bias circuit to IGBT. Speaking of this, maintenance personnel will deeply understand that they should not suffer too much from such losses.
During the maintenance process, the gate resistor DR45 was missed, and during the installation process, only the trigger plug of the upper arm IBGT1 was carelessly inserted, forgetting to connect the lower arm IGBT trigger terminal, resulting in the IGBT2 drive signal introduction terminal being vacant. After power on, the start signal is not activated, and there is no problem. Once the start signal is activated, there is no discussion, and the module is damaged. In my long-term maintenance work, I have developed a habit of stopping for a while before starting the operation after powering on, and observing whether the drive pulse output terminal is properly connected. After checking that each connection is intact, press the start button again. I often feel that this slight point is of great importance – the driving circuit and inverter output circuit are both in a normal state, and only one signal terminal of the driving pulse is missing, which will inevitably cause serious damage to the IGBT module and driving circuit again, resulting in all previous efforts being wasted!

Equivalent diagram of IGBT junction capacitance

Just like bipolar devices – transistors, three wire components inevitably form three equivalent capacitors inside, while the Cge inside IGBTs is not parasitic, but formed by process and structure. Let’s not bother with Cce capacitors. The two capacitors, Ccg and Cge, can have a destructive effect on IGBT.
The above diagram shows the situation when the triggering terminal of the lower arm IGBT is open circuit. After power on, IGBT1 can maintain a reliable cut-off state by applying a negative cut-off voltage to the G and E poles due to the connection of the driving circuit. The reckless input of the frequency converter operation signal causes IGBT1 to be driven by a forward excitation pulse voltage and turn on. The C pole of IGBT2, the U terminal, immediately jumps to a DC high voltage of+530V. This jump voltage provides a charging return circuit for the Ccg and Cge capacitors. During the turning on period of IGBT1, IGBT2 is also driven by this charging current, and it is almost simultaneously turned on. The common connection of the two tubes forms a short circuit to the+530V power supply at the P and N terminals. With a loud bang, both tubes explode! If the signal terminal of the upper tube is empty and the lower tube is connected to the driving circuit, the conduction of the lower tube will also cause damage to both tubes for the same reason.
Assuming that there is a gate bypass resistor connected in parallel on the G and E poles of IGBT2 (such as the R side in the IGBT1 gate control circuit), it will form a bypass effect on the charging current mentioned above, and the possibility of the two transistors sharing the same circuit will be reduced. Assuming that during the conduction period of the upper tube, there is a cut-off negative pressure of about 7V between the G and E terminals of the lower tube, and the positive charging current is neutralized and absorbed by the gate negative bias, which is far from reaching the amplitude required to turn on the IGBT, then IGBT2 is safe. This is also why negative pressure is added to the control circuit of IGBT.
For frequency converters using IPM intelligent inverter modules, the driving power supply is often a single power supply without providing negative pressure. Is that the case?
From a design perspective, the shorter the lead of the IGBT drive signal, the better, in order to reduce the inductance effect of the lead; There should be a small resistance circuit between the E and E poles of the IGBT to fully bypass the interference signal current. The IPM module, driver circuit, and inverter main circuit are integrated inside the module, and the wiring between the driver circuit and IGBT is extremely short. According to data, even the gate resistance is omitted to reduce the wiring impedance. In the off state, IGBT ensures that the gate is in a low impedance grounded state, effectively preventing misleading conduction caused by interference signals, thus eliminating the need for negative power supply.

Posted on 2024年6月1日2024年6月1日 by baiyuzhan — Leave a comment

Maintenance ideas and methods for VFD switching power supply

The switching power supply circuit of VFD can be completely simplified into the circuit model shown in the diagram, and the key elements in the circuit are included. And any complex switching power supply, after removing the branches, will still have a backbone like the one shown in the picture. In fact, in maintenance, it is necessary to have the ability to simplify complex circuits, and to identify these main threads in the seemingly disorderly extension of circuits. To learn from the skilled chef of Jieniu, train yourself that there is no overall switch power circuit in front of your eyes, only the direction of the various parts and veins – oscillation circuit, voltage stabilization circuit, protection circuit, and load circuit, etc.

Take a look at how many veins there are in the circuit.

1.Oscillation circuit: The leakage source and R4 of the main windings N1 and Q1 of the switching transformer are the paths for the working current of the power supply; R1 provides starting current; The self powered windings N2, D1, and C1 form the power supply voltage for the oscillating chip. The normal operation of these three links is a prerequisite for the power supply to oscillate.

Of course, the 4-pin external timing components R2, C2, and PC1 chip itself of PC1 also constitute a part of the oscillation circuit.

2,.Voltage stabilizing circuit: The+5V power supply of N3, D3, C4, etc., and components such as R7-R10, PC3, R5, R6 constitute the voltage stabilizing control circuit.

Of course, the PC1 chip and peripheral components R3 and C3 on pins 1 and 2 are also part of the voltage stabilization circuit.

3.Protection circuit: The PC1 chip itself and the 3-pin peripheral component R4 form an overcurrent protection circuit; The parallel D2, R6, and C4 components on the N1 winding form the protection circuit of the IGBT; In essence, the voltage feedback signal of the voltage stabilizing circuit, the voltage stabilizing signal, can also be regarded as a voltage protection signal. However, the content of protecting the circuit is not limited to the protection circuit itself. The initiation and control of the protection circuit are often caused by abnormalities in the load circuit.

4.Load circuit: N3 and N4 secondary windings and subsequent circuits are all load circuits. The abnormality of the load circuit will involve the protection circuit and the voltage stabilizing circuit, causing the two circuits to make corresponding protection and adjustment actions.

The oscillation chip itself participates in and constitutes the first three circuits. If the chip is damaged, all three circuits will strike together. The maintenance of three or four circuits is carried out under the premise that the chip itself is normal. In addition, like playing chess, we should use a global perspective and systematic approach to diagnose faults, and see the essence through phenomena. If there is a stop vibration fault, it may not be caused by damage to the oscillation circuit components. It may be a voltage stabilization circuit fault or an abnormal load circuit, which causes the internal protection circuit of the chip to start controlling and stops the output of PWM pulses. It is not possible to completely isolate each circuit for maintenance, and the appearance of a faulty component may exhibit the effect of “pulling one engine and moving the whole body”.

Switching power supply circuits often exhibit the following three typical fault phenomena (combined with Figures 3 and 9):
A、 The secondary load supply voltage is 0V. After the frequency converter is powered on, there is no response, and there is no indication on the operation display panel. The measured voltage of 24V and 10V at the control terminal is 0V. If the charging resistance or pre charging circuit of the main circuit is intact, it can be determined that there is a switch power supply fault. The maintenance steps are as follows:

1.First, use the resistance measurement method to measure whether there is any breakdown or short circuit phenomenon in switch Q1, and whether there is an open circuit in the current sampling resistor R4. The easily damaged component of the circuit is the switch tube. When it is damaged, R4 will increase in resistance or open circuit due to impact. The G-pole series resistor and oscillation chip PC1 in Q1 are often damaged by strong electrical shocks and need to be replaced simultaneously; Check for short circuits in the load circuit and eliminate them.

2.If the damaged parts are replaced or there are short circuited components that have not been detected, a power on inspection can be conducted to further determine whether the fault is in the oscillation circuit or the voltage stabilizing circuit.

Inspection method:
a、 First, check if there is an open circuit in the starting resistor R1. After normal operation, use an 18V DC power supply to directly power on pins 7 and 5 of UC3844 to separately power on the oscillation circuit. Measure that pin 8 should have a 5V voltage output; The 6 pins should have a voltage output of about 1V. The oscillation circuit is basically normal, and the fault is in the voltage stabilizing circuit;
If the voltage output of pin 8 is 5V, but the voltage of pin 6 is 0V, check the external R and C timing components of pins 8 and 4, and the peripheral circuit of pin 6;
If the voltage measured on pins 8 and 6 is 0V, the UC3844 oscillation chip is broken and needs to be replaced.

b、 Power on UC3844 separately and short circuit the input side of PC2. If the circuit vibrates, it indicates that the fault is in the peripheral circuit of the input side of PC2; The circuit still does not vibrate, check the PC2 output side circuit.

B、 Intermittent oscillation occurs in the switching power supply, where a “hiccup” or “squeaking” sound can be heard, or a “hiccup” sound cannot be heard, but when the display panel is operated, it lights up and turns off. This is a typical fault characteristic caused by abnormal load circuit, resulting in power overload and triggering overcurrent protection circuit action. The abnormal increase in load current causes a significant increase in the excitation current of the primary winding, forming a voltage signal of more than 1V at the current sampling resistor R4, which activates the internal current detection circuit of UC3844 and causes the circuit to stop vibrating; The overcurrent signal on R4 disappears, and the circuit starts vibrating again. This cycle repeats, causing intermittent oscillations in the power supply.

Inspection method:
a、 Measure the resistance values at both ends of the power supply circuit C4 and C5. If there is a short circuit, it may be due to a short circuit in the rectifier diodes D3 and D4; Observe the appearance of C4 and C5 for any bulging or liquid spraying, and remove them for inspection if necessary; There is no abnormality in the power supply circuit, which may be due to a short circuit fault component in the load circuit;
b、 Check the power supply circuit for any abnormalities, power on, and use the troubleshooting method to troubleshoot each power supply one by one. If the power supply terminal of the fan is unplugged, the switch power supply works normally, and the operation display panel displays normally, it indicates that the 24V cooling fan has been damaged; If the+5V power supply connector is unplugged or the power supply copper foil is cut off, and the switch power supply is working normally, it indicates that there are damaged components in the+5V load circuit.

C、 The supply voltage of the load circuit is too high or too low. The oscillation circuit of the switching power supply is normal, but the problem lies in the voltage stabilizing circuit.

The output voltage is too high, and the components of the voltage stabilizing circuit are damaged or inefficient, resulting in insufficient feedback voltage amplitude. Inspection method:
a、 Connect a 10k resistor in parallel to the output terminal of PC2, and the output voltage drops back. The output side voltage stabilizing circuit of PC2 is normal, and the fault lies in both the PC2 itself and the input side circuit;
b、 Parallel connection of a 500 Ω resistor on R7 results in a significant drop in output voltage. The optocoupler PC2 is in good condition, but the fault is low efficiency of PC3 or a change in the value of the external resistor component of PC3. On the contrary, it is PC2 defect.
If the load supply voltage is too low, there are three possible faults: 1. The load is too heavy, causing a decrease in output voltage; 2. Poor components of the voltage stabilizing circuit result in excessive voltage feedback signals; 3. The switch tube is inefficient, causing insufficient energy exchange in the circuit (switch transformer).

Inspection and repair methods:
a、 Remove the load circuits of the power supply branch one by one (note! Do not disconnect the load circuit by opening the power supply rectifier tube of that branch, especially the+5V power supply circuit with a voltage stabilizing feedback signal! The disappearance of the feedback voltage signal will cause abnormal increase in output voltage of each branch, and burn out large areas of the load circuit!) Determine whether the voltage drop is caused by excessive load; If the circuit returns to normal after cutting off a certain power supply, it indicates that the switching power supply itself is normal. Check the load circuit; Low output voltage, check the voltage stabilizing circuit.
b、 Check the resistance components R5-R10 of the voltage stabilizing circuit, and there is no change in value; Replace PC2 and PC3 one by one. If everything is normal, it indicates that the replacement components are inefficient and the internal resistance of conduction increases.
c、 If replacing PC2 and PC3 is ineffective, the fault may be low efficiency of the switch tube, or there may be problems with the switch and excitation circuit, which does not rule out the low efficiency of the internal output circuit of UC3844. Replace high-quality switch tubes and UC3844.

For general faults, the above troubleshooting methods are effective, but not necessarily 100% effective. If there are no abnormalities in the oscillation circuit, voltage stabilization circuit, or load circuit, but the circuit still has low output voltage, intermittent oscillation, or simply no response, this situation may occur. Don’t worry for now, let’s delve deeper into the cause of the circuit malfunction to help identify the faulty component as soon as possible. What other reasons can cause the circuit to not vibrate when the intermittent oscillation or stoppage of the circuit is not caused by the starting and stabilizing circuits?

(1) The R, D, and C circuits with parallel connection at both ends of the main winding N1 serve as a peak voltage absorption network, providing a discharge path for the magnetic field energy stored in the transformer during the switching period (reverse current channel of the switching tube), protecting the switching tube from overvoltage breakdown. When D2 or C4 experiences severe leakage or breakdown short circuit, the power supply is equivalent to adding a heavy load, causing the output voltage to drop significantly. U3844 lacks power supply, and the internal undervoltage protection circuit is activated, leading to intermittent oscillation of the circuit. Due to the parallel connection of components on the N1 winding, it is difficult to detect a short circuit and is often overlooked;
(2) Some switch mode power supplies have a protection circuit with an input power supply voltage (high voltage). Once the circuit itself malfunctions, the circuit will experience a false overvoltage protection action and the circuit will stop vibrating;
(3) Poor current sampling resistance, such as pin oxidation, carbonization, or increased resistance, can lead to an increase in voltage drop, resulting in false overcurrent protection and causing the circuit to enter an intermittent oscillation state;
(4) The rectifier diode D1 of the self powered winding is inefficient, and the forward conduction internal resistance increases, causing the circuit to fail to vibrate. Replacement testing is required;
(5) The quality factor of the switch transformer is reduced due to mold and moisture in the winding, and the original model transformer is used for replacement testing;
(6) The parameters of the R1 oscillation circuit vary, but no abnormalities are detected in the measurement, or the switching tube is inefficient. At this time, the circuit is checked and found to be normal, but it does not vibrate.

Repair method:
Change the existing parameters and status of the circuit to expose the fault! Try reducing the resistance value of R1 (not less than 200k Ω) so that the circuit can vibrate. This method can also be used as one of the emergency repair methods. Invalid, replace switch tube, UC3844, switch transformer test.
The output voltage is always slightly higher or lower, and cannot reach the normal value. Unable to detect any abnormalities in the circuit or components, almost all components in the circuit were replaced. The output voltage value of the circuit is still in a “barely and barely” state, sometimes seeming to work “normally”, but it makes people feel uneasy, as if they are neurotic, and I don’t know when an “abnormal performance” will occur. Don’t give up, adjust the circuit parameters to make the output circuit reach its normal value and reach its working state, so that we can rest assured. There are several reasons for the variation of circuit parameters:

a、 Transistors are inefficient, such as a decrease in the amplification factor of the transistor, an increase in the internal resistance of conduction, an increase in the forward resistance of the diode, and a decrease in the reverse resistance;
b、 The related dielectric loss, frequency loss, etc. of capacitors that cannot be measured with a multimeter;
c、 Aging and parameter drift of transistors and chip devices, such as decreased light transfer efficiency of optocouplers;
d、 Inductive components, such as switch transformers, have reduced Q values, etc;
e、 The resistance variation of resistive components is not significant.
f、 There are several factors involved in the above 5 reasons, forming a “comprehensive effect”.
The “current” state of a circuit formed by various reasons is a “pathological” state. Perhaps we need to change our maintenance approach. Traditional Chinese medicine has a “dialectical treatment” theory, and we also need to use it. The next prescription is not to target a specific component, but to “regulate” the entire circuit, making it from “pathological” to “normal”. Just like this, the illness was treated with confusion and confusion.
Repair method (slight adjustment of component values):

(1) Low output voltage:
a、 Increase R5 or decrease R6 resistance value; b、 Reduce the resistance values of R7 and R8 or increase the resistance values of R9.
(2) High output voltage:
a、 Reduce R5 or increase R6 resistance value; b、 Increase the resistance values of R7 and R8 or decrease the resistance values of R9.
The purpose of the above adjustments is to thoroughly inspect the circuit and replace inefficient components before proceeding. The purpose is to adjust the relevant gain of the stabilizing feedback circuit, so that the pulse duty cycle of the oscillation chip output changes, the energy storage of the switching transformer changes, and the output voltage of the secondary winding reaches the normal value, and the circuit enters a new “normal balance” state.
Many seemingly irreparable and difficult faults were repaired with ease after adjusting one or two resistance values.

During maintenance, attention should be paid to the following issues: 1. During the inspection and repair process of the switching power supply, the power supply to the IGBT module of the three-phase output circuit should be cut off to prevent abnormal driving power supply and damage to the IGBT module; 2. When repairing faults with high output voltage, it is even more important to cut off the+5V power supply to the CPU motherboard to avoid abnormal or high voltage damage to the CPU, resulting in the CPU motherboard being scrapped. 3. Do not interrupt the voltage stabilizing circuit, as it will cause an abnormal increase in output voltage! 4. The diodes in switch mode power supply circuits, used for rectification and protection, are both high-speed diodes or Schottky diodes and cannot be replaced by ordinary IN4000 series rectifier diodes. 4. After the switch tube is damaged, it is best to replace it with the original model. With such a developed network, the source of goods is not a problem and can generally be purchased. Many things can be purchased at cheap prices on Taobao, pay attention to quality!

Posted on 2024年5月27日2024年5月27日 by baiyuzhan — Leave a comment

Communication Application of Mitsubishi FX2NPLC and Mitsubishi VFD ModbusRTU Protocol

Modbus is a serial communication protocol invented by Modicon for the communication between its PLC and the host. Its physical layer adopts asynchronous serial standards such as RS232 and 485. Due to its openness, it is widely adopted by PLC and RTU manufacturers. The Modbus communication method adopts a master-slave query corresponding mechanism. Only when the master station sends a query, the slave station can provide a response, and the slave station cannot actively send data. The master station can send queries to a certain slave station or broadcast information to all slave stations. The slave station only responds to queries sent to it separately, and does not respond to broadcast messages. There are two transmission methods for MODBUS communication protocol: RTU mode and ASCII mode. The Mitsubishi 700 series frequency converter can use the ModbusRTU communication protocol from the RS-485 terminal for communication operation and parameter settings.

Object:

Mitsubishi PLC: FX2N+FX2N-485-BD
Mitsubishi frequency converter: F700 series, A700 series.
The two are connected through Ethernet cables, as shown in the following figure.

Connection diagram between FX2N-485-BD and n VFDs

1、 Setting up Mitsubishi frequency converters
When communicating between PLC and frequency converter, the communication specifications must be set in the frequency converter. After each parameter initialization setting, the frequency converter needs to be reset or the power supply of the frequency converter needs to be turned on and off.
Parameter Number Name Setting Value Description
Pr331 communication station number 1 sets the frequency converter station number to 1
Pr332 communication speed 96, set communication speed to 9600bps
Pr334 parity check stop bit length 2 even check, stop bit length 1 bit
Pr539 communication verification time 9999 does not perform communication verification
Pr549 protocol selection 1 ModbusRTU protocol
Pr551 PU mode operation right selection 2 PU operation mode operation right as PU interface
When communicating with ModbusRTU protocol, Pr551 must be set to 2, Pr340 is set to a value other than 0, Set Pr79 to 0, 2, or 6. When using the RS-485 terminal for ModbusRTU protocol communication, it must be running in NET network mode.

2、 Settings of Mitsubishi PLC
Set communication format D8120
The setting value of D8120 is 0C87, which means the data length is 8 bits, the parity stop bit is 1 bit, the baud rate is 9600pbs, and there is no header or terminator.
After modifying the D8120 settings, ensure that the PLC power is turned on and off once.

3、 Communication program
The partial PLC program that uses ModbusRTU protocol to communicate with the frequency converter is as follows:

Posted on 2024年5月24日2024年8月6日 by baiyuzhan — Leave a comment

Signal conversion circuit from 0-10VDC to 4-20mA

Remote pressure gauges are often used in variable frequency water supply control systems, with resistance values ranging from 100 ohms to 500 ohms, corresponding to continuously changing pressure range values, such as 0-10mpa. This continuously changing resistor can be directly applied by serializing a larger resistor and applying a 0-10V signal to obtain the continuously changing voltage for use by the frequency converter, PLC, and other controllers. In practical engineering applications, 4-20mA has stronger anti-interference ability than 0-10VD, so it is often necessary to use 4-20mA signals for transmission control. At this time, resistance signals or voltage signals need to be converted into 4-20mA signals. Some frequency converter manufacturers have developed such water supply signal acquisition boards, and there are also related signal conversion boards on the market. These boards can be applied in various situations, not just constant pressure water supply control systems. The following are three conversion circuits for learning and reference.

A certain frequency converter manufacturer has developed a water supply substrate R/I conversion circuit board for this purpose, which converts the resistance change of the remote pressure gauge into a 4-20mA current signal and inputs it to the control terminal. This signal is compared with the given pressure signal (parameter setting value), automatically adjusting the output frequency of the frequency converter to maintain a constant pressure in the water supply network. A 4-20mA signal source circuit is actually a constant current source circuit with a large internal resistance, and the output current depends on the internal resistance, regardless of the external load resistance. In a closed circuit, even if the load resistance value is 0, the original output current value can still be maintained unchanged. T2 and T3 form two constant current source circuits, the former being a “constant” constant current source circuit and the latter being a “variable” constant current source electrical appliance. The 12V DC voltage from the CPU motherboard is transmitted through D1 C4 isolation and filtering become the power supply for the Vcc1 water supply substrate. R1 and TL431 further process Vcc1 into a reference voltage of 2.5V, which is then processed by TL431, operational amplifier circuit R2、Z2、 Internal resistance of remote pressure gauge T2 circuit, forming 2.5V/510 Ω=4 A constant current circuit of 9 mA. Due to Z1 The Z2 and T2 circuits have a constant current circuit of 4.9 mA, and the resistance change of the remote transmission pressure gauge is converted to the voltage change on the Z2 resistor. This pipeline pressure signal is input to pins 5 and 6 of the second stage operational amplifier circuit through R3. Second stage operational amplifier circuit T3 forms a “variable” constant current source circuit, where the change in resistance inside the remote pressure gauge is converted into signal voltage input to the two input terminals of the operational amplifier. This stage amplifier forms a constant current source circuit with deep negative feedback (amplification factor of 1), and the output current depends on the size of the resistance inside the remote pressure gauge. Z1 and Z3 are voltage embedded protection diodes for signal input and output terminals. The internal resistance of the current input terminals of the frequency converter is generally 250 Ω.
The bottom left image shows a dedicated signal conversion chip for 0-10V/4-20mA, with the chip model of AD694. The control terminal of the frequency converter itself has a 24V power supply, and the chip only needs to connect a current limiting resistor and a transistor to accurately convert the signal. The anti-interference performance of the chip is also relatively good; The bottom right image is a 0-10V/4-20mA signal conversion circuit composed of an operational amplifier circuit and discrete components. The circuit requires two power supplies and adjustment of the initial output current, which is relatively cumbersome and not widely used.

Posted on 2024年3月28日2024年3月28日 by baiyuzhan — Leave a comment

Analysis of Zero Position Adjustment for Incremental Optoelectronic Encoder for Initial Position Detection of Permanent Magnet Synchronous Motor Rotors

The mainstream servo motor position feedback components include incremental encoders, absolute encoders, rotary transformers, etc. The vector control of permanent magnet AC servo drive requires a position feedback component to provide the position information of the rotor D-axis of the permanent magnet motor to the servo driver. After the position feedback component is installed with the motor, it is necessary to obtain the position relationship between the rotor magnetic pole axis (D) axis and the motor A-phase axis through the position feedback component before the driver starts vector control. Taking an incremental photoelectric encoder as an example, the encoder provides the position increment and zero position Z signal information to the controller’s main control chip, and uses these three sets of signals to determine the motor position of the motor. In actual use, the incremental photoelectric encoder also provides three additional sets of UVW signals for roughly determining the initial position of the rotor D-axis during motor startup. The rising edge of the encoder U signal and the rising edge of the Z trigger signal are generally aligned. The problem is that when the encoder is installed on the motor shaft, it may be fixed at a certain position of 360 degrees relative to the motor A-phase axis (after the motor winding stator is assembled). If the angle at this position is not known, the position information of the D-axis of the motor rotor cannot be determined using the output signal of the incremental photoelectric encoder, and vector control of the motor cannot be completed. Therefore, it is necessary to obtain this position signal through certain adjustment methods, which can be called electrical angle phase initialization, encoder zero position adjustment or alignment.

The physical significance of the signals of incremental encoders and the concept of axis position of permanent magnet synchronous motors

1. The A-phase axis of the motor and the orientation of the magnetic field

A permanent magnet motor is composed of three phase winding coils that are energized to form a rotating magnetic field, which is carried to the rotor poles equipped with rotor magnetic steel for rotation. The three phase windings form their own spatial magnetic potential vectors, and these three magnetic potentials combine to form a rotating magnetic potential vector: Figure 1 is a schematic diagram of the axial section layout of the motor winding. The A phase coil head is A-tail X, the B phase coil head is B-tail Y, and the C phase coil head is C-tail Z, connected in a star shape. XYZ is connected together, and the “+” and “-” in the ABC small circle represent the positive direction of the motor current of each phase equivalent coil (flowing from the beginning). When each phase coil is energized with a positive current, the arrows in the diagram are A and B according to the right-hand rule when the positive direction current is applied to the right hand direction. The direction of the magnetic potential (field) of A, B, and C when the positive direction current is applied to the three-phase coil, i.e. the respective axes of A, B, and C.

Assuming that when phase A flows in (positive direction) 1A, the current flowing out from phases B and C is -0.5A each (negative sign indicates opposite to the specified positive direction), as shown in Figure 2, the actual current at the coil edge of AZBXCY is+1+0.5-0.5-1-0.5+0.5 when unfolded counterclockwise along the cross-section. It can be seen that there are continuous positive current directions in the 180 degree electrical angle area along the circumference, and the other 180 continuous negative current directions are symmetrically distributed. The direction of the magnetic potential field determined by the right-hand rule in Figure 2 is the arrow direction shown in Figure 2, that is, the synthesized magnetic field is on the A-phase axis.

When powering on phases B and C, the current flows from phase B to phase C, as shown in Figure 3. The direction of the three-phase magnetic field is 90 degrees ahead of the axis of phase A.

2. The physical meaning of each output signal of the incremental photoelectric encoder

The commonly used incremental photoelectric encoder is a type of encoder with simple magnetic pole positioning function, which has two sets of output information: one set of information is A, B, Z; The other group is U, V, W, used to detect the position of magnetic poles, with absolute information function. Among them, A and B are basic signals, which can be processed to conveniently determine the direction and speed of motor rotation; Z pulses are used for reference positioning, with a phase difference of 120 degrees between the U, V, and W pulses. The number of pulses per revolution is consistent with the number of pole pairs of the motor. The use of U, V, and W signals can serve as a starting point for rough measurement of rotor position. After the motor starts, the precise angular position is obtained from signals A and B.

3. A deeper understanding of encoder output signals and motor position signals

A permanent magnet synchronous motor using an incremental photoelectric encoder as a position detection component must have its precise initial position measured when the system is first powered on. Because in the permanent magnet motor drive system, the position detection and initial positioning of the motor rotor are the basic conditions for system composition and operation, as well as the necessary conditions for vector control decoupling. Only when the rotor position of a permanent magnet synchronous motor can be accurately known, can the permanent magnet synchronous motor be equivalently transformed into an equivalent model on the dq coordinate system according to a series of equations in vector control. The system can control the permanent magnet synchronous motor using a control method similar to that of a separately excited DC motor, thus achieving the performance requirements of a servo transmission system composed of separately excited DC motors. In the driving system that uses an incremental photoelectric encoder to measure the position of the motor, the initial position of the motor needs to be detected first after the system is powered on. The initial position of the motor not only affects the positioning accuracy of the servo system, but also has a certain impact on the fast starting performance of the motor.

Taking a permanent magnet synchronous motor as an example, Figure 4 is the simplest diagram of the position relationship between the stator winding, magnetic steel, and HALL of the motor, with the rotor magnetic poles rotating uniformly counterclockwise. At the position shown in the diagram, the stator coil phase A crosses the zero point. If the DC brushless motor has a maximum output power when the current and back electromotive force are in the same phase due to 120 degrees conduction, and the U-phase voltage switch tube is delayed by 30 degrees of electrical angle conduction, the installation position of the HALL should be rotated counterclockwise over 30 degrees of electrical angle. The three sets of signal encoding outputs of the HALL output of a DC brushless motor reflect the motor position signal. The 360 degree electrical angle space is evenly divided into six consecutive spaces, each occupying 60 degrees of electrical angle.

The UVW signal of the encoder is similar to the DC brushless HALL signal, so it can also play this role
What is the difference between the function and the HALL output signal? Three HALLs have been installed by
On the three-phase axis shown in Figure 1, the three-phase HALL output signal not only reflects the rotor position signal, but also
The information also includes the three-phase axis of the stator, so that the position information of the stator and rotor can be communicated
By matching with HALL, the angle and position information of the rotor relative to the stator axis can be found. When
After the encoder is installed, the UVW signal of the photoelectric encoder is input on the encoder disk
If a position sensor similar to HALL is placed on the encoder disk (actually
Similarly, when the zero position of the rotor magnetic potential (transition position between N and S poles) is rotated past this position
The U-phase signal of the photoelectric encoder undergoes a jump, and the rising edge of the U-phase signal can reflect the magnetic field of the rotor
The position of the polar axis (D-axis) triggers the rising edge of the Z-signal (encoder zero position) and the U-signal
The rising edge of the signal is consistent, so the Z trigger signal can reflect the position of the rotor’s D-axis at that time. The problem is,
The rising edge of the U-phase signal of the photoelectric encoder can reflect the position of the rotor magnetic pole axis (D-axis), when
The position of the rotor magnetic pole axis (D-axis) and the motor winding when the photoelectric encoder emits a Z signal pulse
The angle between the A-phase axes (compensation angle parameter in TI PMSM 3.1 routine QEP module)
The number is CalibratedAngle, but it needs to be converted to the pulse number of the photoelectric encoder.
4.Correction of the angle between the encoder Z signal and the motor A phase axis position
After the installation of the photoelectric encoder, when the rotor rotates, the position where the z signal is triggered may be in the range of
At a fixed angle of 360 degrees electrical angle with the A-phase axis of the motor as the reference zero point, so Compared to the HALL output signal, there is a missing link, which is the failure to phase the UVW signal with A Corresponding axes. This requires finding out this angle, which is usually achieved through the soft Correct the parts.

As shown in Figure 5, a two channel oscilloscope is used to observe the opposite potential of A and the contact of the encoder Z signal The time relationship of the generator position is determined by making the motor rotate at a constant speed and connecting three resistors with equal resistance values to form a star Then connect the three resistors connected in a star pattern to the UVW three-phase winding of the motor Line. In the figure, R is the external resistance, La, Lb, and Lc are the three-phase inductance of the motor stator, Ra Rb and Rc are the three-phase resistances of the motor stator, because the resistance of the motor stator is usually very small, as long as If the external resistance R is large enough, the stator resistance is ignored.

Use an oscilloscope to observe the output of motor A phase By focusing on the star type resistor, obtain the back electromotive force waveform of motor phase A.The period of the opposite electromotive force of motor A and the encoder Z signal and back electromotive force can be obtained from the oscilloscope The time difference between the zero crossing point of the waveform from low to high can be used to obtain the motor A phase axis and encoder Z signal

The angle difference of the number is:

The period T of the opposite electromotive force from motor A and the waveform of the encoder Z signal and the back electromotive force from low to high The time difference between zero crossing can be used to calculate the corrected number of pulses, and the encoder zero can be corrected through software The phase relationship with the axis of stator A.

Installation of encoder and adjustment or alignment of encoder zero position

The above detailed description describes the method of correcting the angle between the encoder zero point and the stator A phase axis. In practice Many manufacturers in production directly align the zero point of the encoder when installing it, and the back electromotive force decreases from low to low There are two methods for crossing the zero point position: one is to cross the zero point from low to high with the opposite electromotive force of A Position alignment, another method is to align with the zero crossing point of the back electromotive force of the AB line from low to high.

1.Align the U-phase signal of the encoder (encoder zero point) with the zero point of the motor electrical angle A opposite to the zero crossing position of the electromotive force
a. Use a DC power source to apply a DC current smaller than the rated current to the UVW winding of the motor,
A in, BC out, as shown in Figure 2, orient the motor shaft to a balanced position;
b. Observe the U-phase signal and Z-signal of the encoder using an oscilloscope;
c. Adjust the relative position between the encoder shaft and the motor shaft;
d. While adjusting, observe the encoder U-phase signal jump edge and Z-signal until Z-signal
The signal is stable at a high level (where the normal state of the Z signal is low), and the encoder is locked
The relative position relationship with the motor;
e. Twist the motor shaft back and forth, and after letting go, if the motor shaft returns to the balance position freely each time,
If the Z signal can stabilize at a high level, then alignment is effective.

2.Align the U-phase signal of the encoder (encoder zero point) with the zero point of the motor electrical angle, i.e. the zero crossing position of the AB line back electromotive force
a. Apply a DC power supply to the AB winding of the motor with a DC current less than the rated current,
A in, B out, orient the motor shaft to a balanced position;
b. Observe the U-phase signal and Z-signal of the encoder using an oscilloscope;
c. Adjust the relative position between the encoder shaft and the motor shaft;
d. While adjusting, observe the encoder U-phase signal jump edge and Z-signal until Z-signal
The signal is stable at a high level (assuming that the normal state of the Z signal is low), locking the encoder and
The relative position relationship of the motor;
e. Twist the motor shaft back and forth, and after letting go, if the motor shaft returns to the balance position freely each time,
If the Z signal can stabilize at a high level, then alignment is effective

Posted on 2024年2月2日2024年4月8日 by baiyuzhan — Leave a comment

Abb Acs580 Fault Code 7122,What does this fault code mean and how can it be reset?

The ACS580 stands as an upgraded iteration compared to the previous ABB ACS550 inverter, boasting enhanced functionalities like vector control. Its versatile applications cover a wide range. Internally, the ACS580 exhibits a distinct circuit structure from its predecessor, the ACS550. In the course of ACS580 usage, encountering various faults and alarm scenarios is common. However, the fault codes and alarms differ significantly from those of the ACS550, necessitating reference to the ACS580 firmware manual for troubleshooting.

In practical scenarios, some fault codes encountered with the ACS580 may not be documented in the manual, presenting a unique challenge. This situation often leaves many electrical engineers puzzled. For instance, a typical fault code such as “7122” cannot be located in any of the ACS580 manuals. Below, you’ll find a table detailing fault codes for the ACS580.

In the provided table, we notice adjacent fault codes like 7121 and 7181, yet codes like 7122, 7123, 7124, and so forth are conspicuously absent. When faced with such a scenario, how does one determine the meaning of abb acs580 fault code 7122?

Those familiar with the internal hardware structure of the ACS580 inverter understand that the high-power mainboard of the ACS580 closely resembles that of the ACS880. In pursuit of clarity, we consulted the firmware manual for the ACS880 and searched its fault code table, only to find no mention of code 7122, as displayed below:

It’s evident that although there are some differences in the fault code listings between the ACS580 and ACS880, the explanations for the fault alarm content are nearly identical as long as the codes match. This demonstrates that many fault code contents in ABB inverters can be cross-referenced within a series. However, it’s regrettable that even in the ACS880’s code table, an explanation for “7122” cannot be found.

Finding ourselves in a predicament, with neither inverter providing an explanation for fault code “7122,” what can we do next?

Upon further exploration, we recall that ABB also offers a compact low-power inverter called the ACS150, which shares hardware and software structures similar to the ACS550. Considering this, the upgraded version of the ACS150 should be the ACS180. We swiftly locate the firmware manual for the ACS180 and navigate to the vicinity of the fault code table. To our amazement, a miracle unfolds, as depicted in the table below:

The table clearly indicates that “7122” is an overload alarm, further specifying that it’s caused by excessively high motor current. Besides verifying if the motor is genuinely overloaded, it’s also necessary to inspect parameters 35.51, 35.52, 35.53, 35.55, and 35.56. Upon comparing these parameters in the ACS580 firmware manual, astonishingly, they closely resemble those in the ACS180. Parameter 35.51 defaults to 110%, but in such cases, it can be adjusted higher, say 150%. However, this adjustment necessitates ensuring that the motor hardware is in good condition and the motor power meets the on-site load requirements.

Further investigation reveals that the ACS180 inverter does include parameter 35.56, whereas the ACS580 does not offer this parameter as an option. Interestingly, setting parameter 35.56 to 0 can effectively disable motor overload alarms, effectively masking fault code 7122.

This indicates that the hardware and software of ABB’s drives—ACS180, ACS580, and ACS880—are essentially the same. Perhaps their underlying programs are identical, and they merely display different series and functionalities through specific settings. Fault code 7122 and the hardware detection function are present in each inverter model, but in the ACS580 and ACS880, the hardware circuitry suppresses it. However, if there’s an issue with the hardware circuitry, such as poor contact or breakage in the connection between the mainboard and the drive board, it may trigger fault code 7122 directly, with no apparent means of suppression, and the fault alarm details may not be found in the inverter’s manual.

Conclusion: When fault codes like 7122 appear on ACS580 or ACS880 inverters, it’s usually indicative of an internal hardware circuit problem. In such cases, removing the inverter, checking the connections and plugs, and clearing dust may resolve the issue. If this doesn’t suffice, it’s likely that a component on the board is faulty, requiring the inverter to be repaired.

Posted on 2024年1月31日2024年2月19日 by baiyuzhan — Leave a comment

Characteristics of ACS800 Drivers, abb acs800 troubleshooting manual

The ACS800 inverter, produced by ABB, is an advanced industrial frequency converter with several unique features that make it highly favored in the industrial control and drive sectors.

Firstly, the ACS800 inverter boasts a wide power range, from kilowatts to megawatts, suitable for various scales and complexities of industrial applications. This flexibility enables the ACS800 to meet the needs of different industries and applications, from small production lines to large factories.

Secondly, the ACS800 inverter exhibits outstanding performance and stability. It employs advanced control algorithms and technologies to achieve precise speed and torque control, ensuring stable and reliable equipment operation. Whether in harsh industrial environmental conditions or demanding production processes, the ACS800 performs exceptionally well.

Furthermore, the ACS800 inverter offers extensive features and options. It supports multiple communication interfaces for integration with various control systems, enabling flexible remote control and monitoring. Additionally, the ACS800 provides various protection functions, such as overload protection, short-circuit protection, and overvoltage protection, effectively safeguarding the safe operation of equipment and production systems.

The ACS800 inverter also emphasizes energy efficiency and environmental protection. By optimizing energy utilization and efficiency, the ACS800 can reduce energy consumption and production costs while minimizing environmental impact, in line with sustainable development requirements.

In conclusion, the ACS800 inverter, with its wide application range, excellent performance, rich features, and eco-friendly energy-saving characteristics, is an ideal choice for industrial control and drive applications. It not only improves production efficiency and quality but also reduces operating costs, creating greater value for users.Below is the ABB ACS800 troubleshooting manual.

Warning or Fault Message On The Panel Display Of ABB ACS800

An indication of an abnormal drive status appears as a warning or fault message on the panel display. You depend on the abb acs800 troubleshooting manual,Utilizing this information, most causes of warnings and faults can be identified and rectified. Should you encounter challenges beyond your expertise, do not hesitate to reach out to us for assistance.When you encounter a malfunction in the ABB ACS800 drive, you can also directly refer to this manual:

https://drive.google.com/file/d/1xIHyXqzHP-my4EsTVidbco33lgYWFXH5/view?usp=sharing

WARNING	CAUSE	WHAT TO DO
ACS800 TEMP (4210) 3.08 AW 1 bit 4	Drive IGBT temperature is excessive. Fault trip limit is 100%.	Check ambient conditions. Check air flow and fan operation. Check heatsink fins for dust pick-up. Check motor power against unit power.
AI < MIN FUNC (8110) 3.09 AW 2 bit 10 (programmable Fault Function 30.01)	Analogue control signal is below minimum allowed value due to incorrect signal level or failure in control wiring.	Check for proper analogue control signal levels. Check control wiring. Check Fault Function parameters.
AD [message]	Message generated by an EVENT block in the Adaptive Program.	Consult the documentation or author of the Adaptive Program.
BACKUP USED (FFA3)	PC stored backup of drive parameters is downloaded into use.	Wait until download is completed.
BATT FAILURE (5581) 3.18 AW 5 bit 15	APBU branching unit memory backup battery error caused by – incorrect APBU switch S3 setting – too low battery voltage.	With parallel connected inverters, enable backup battery by setting actuator 6 of switch S3 to ON. Replace backup battery.
BC OVERHEAT (7114) 3.18 AW 5 bit 3	Brake chopper overload	Stop drive. Let chopper cool down. Check parameter settings of resistor overload protection function (see parameter group 27 BRAKE CHOPPER). Check that braking cycle meets allowed limits. Check that drive supply AC voltage is not excessive.
BRAKE ACKN (FF74) 3.16 AW 4 bit 3	Unexpected state of brake acknowledge signal	See parameter group 42 BRAKE CONTROL. Check connection of brake acknowledgement signal.
BR OVERHEAT (7112) 3.18 AW 5 bit 2	Brake resistor overload	Stop drive. Let resistor cool down. Check parameter settings of resistor overload protection function (see parameter group 27 BRAKE CHOPPER). Check that braking cycle meets allowed limits.
CALIBRA DONE (FF37)	Calibration of output current transformers is completed.	Continue normal operation.
CALIBRA REQ (FF36)	Calibration of output current transformers is required. Displayed at start if drive is in scalar control (parameter 99.04) and scalar fly start feature is on (parameter 21.08).	Calibration starts automatically. Wait for a while.

WARNING	CAUSE	WHAT TO DO
COMM MODULE (7510) 3.08 AW 1 bit 12 (programmable Fault Function 30.18, 30.19)	Cyclical communication between drive and master is lost.	Check status of fieldbus communication. See chapter Fieldbus control, or appropriate fieldbus adapter manual. Check parameter settings: – group 51 COMM MODULE DATA (for fieldbus adapter) – group 52 STANDARD MODBUS (for Standard Modbus Link). Check Fault Function parameters. Check cable connections. Check if master can communicate.
DC BUS LIM (3211) 3.18 AW5 bit 9 (programmable Fault Function 30.23)	Drive limits torque due to too high or too low intermediate circuit DC voltage.	Informative alarm Check Fault Function parameters.
EARTH FAULT (2330) 3.08 AW 1 bit 14 (programmable Fault Function 30.17)	Drive has detected load unbalance typically due to earth fault in motor or motor cable.	Check there are no power factor correction capacitors or surge absorbers in motor cable. Check that there is no earth fault in motor or motor cables: – measure insulation resistances of motor and motor cable. If no earth fault can be detected, contact your local ABB representative.
ENC CABLE (7310) 3.31 AW 6 bit 3 (programmable Fault Function 50.07)	Pulse encoder phase signal is missing.	Check pulse encoder and its wiring. Check pulse encoder interface module and its wiring.
ENCODER A<>B (7302) 3.09 AW 2 bit 4	Pulse encoder phasing is wrong: Phase A is connected to terminal of phase B and vice versa.	Interchange connection of pulse encoder phases A and B.
ENCODER ERR (7301) 3.08 AW 1 bit 5	Communication fault between pulse encoder and pulse encoder interface module and between module and drive	Check pulse encoder and its wiring, pulse encoder interface module and its wiring, parameter group 50 ENCODER MODULE settings.
FAN OTEMP (FF83) 3.16 AW 4 bit 0	Excessive temperature of drive output filter fan. Supervision is in use in step-up drives.	Stop drive. Let it cool down. Check ambient temperature. Check fan rotates in correct direction and air flows freely.
HW RECONF RQ (FF38)	Inverter type (e.g. sr0025_3) has been changed. Inverter type is usually changed at factory or during drive implementation.	Wait until alarm POWEROFF! activates and switch control board power off to validate inverter type change.

WARNING	CAUSE	WHAT TO DO
ID DONE (FF32)	Drive has performed motor identification magnetisation and is ready for operation. This warning belongs to normal start-up procedure.	Continue drive operation.
ID MAGN (FF31)	Motor identification magnetisation is on. This warning belongs to normal start-up procedure.	Wait until drive indicates that motor identification is completed.
ID MAGN REQ (FF30)	Motor identification is required. This warning belongs to normal start-up procedure. Drive expects user to select how motor identification should be performed: By Identification Magnetisation or by ID Run.	Start Identification Magnetisation by pressing Start key, or select ID Run and start (see parameter 99.10).
ID N CHANGED (FF68)	Drive ID number has been changed from 1.	Change ID number back to 1. See chapter Control panel.
ID RUN (FF35)	Motor identification Run is on.	Wait until drive indicates that motor identification Run is completed.
ID RUN SEL (FF33)	Motor Identification Run is selected, and drive is ready to start ID Run. This warning belongs to ID Run procedure.	Press Start key to start Identification Run.
IN CHOKE TEMP (FF81) 3.18 AW 5 bit 4	Excessive input choke temperature	Stop drive. Let it cool down. Check ambient temperature. Check that fan rotates in correct direction and air flows freely.
INV CUR LIM (2212) 3.18 AW 5 bit 8 (programmable Fault Function 30.23)	Internal inverter current or power limit has been exceeded.	Reduce load or increase ramp time. Limit inverter actual power or decrease line- side converter reactive power generation reference value (parameter 95.06 LCU Q PW REF). Check Fault Function parameters.
INV DISABLED (3200) 3.18 AW 5 bit 6	Optional DC switch has opened while unit was stopped.	Close DC switch. Check AFSC-0x Fuse Switch Controller unit.

WARNING	CAUSE	WHAT TO DO
INV OVERTEMP (4290) 3.31 AW 6 bit 0	Converter module temperature is excessive.	Check ambient temperature. If it exceeds 40°C, ensure that load current does not exceed derated load capacity of drive. See appropriate hardware manual. Check that ambient temperature setting is correct (parameter 95.10). Check converter module cooling air flow and fan operation. Cabinet installation: Check cabinet air inlet filters. Change when necessary. See appropriate hardware manual. Modules installed in cabinet by user: Check that cooling air circulation in cabinet has been prevented with air baffles. See module installation instructions. Check inside of cabinet and heatsink of converter module for dust pick-up. Clean when necessary.
IO CONFIG (FF8B) (programmable Fault Function 30.22)	Input or output of optional I/O extension or fieldbus module has been selected as signal interface in application program but communication to appropriate I/O extension module has not been set accordingly.	Check Fault Function parameters. Check parameter group 98 OPTION MODULES.
MACRO CHANGE (FF69)	Macro is restoring or User macro is being saved.	Wait until drive has finished task.
MOD BOARD T (FF88) 09.11 AW 3 bit 14	Overtemperature in AINT board of inverter module.	Check inverter fan. Check ambient temperature.
MOD CHOKE T (FF89) 09.11 AW 3 bit 13	Overtemperature in choke of liquid cooled R8i inverter module.	Check inverter fan. Check ambient temperature. Check liquid cooling system.
MOT CUR LIM (2300) 3.18 AW 5 bit 10 (programmable Fault Function 30.23)	Drive limits motor current according to current limit defined by parameter 20.03 MAXIMUM CURRENT.	Reduce load or increase ramp time. Increase parameter 20.03 MAXIMUM CURRENT value. Check Fault Function parameters.
MOTOR STALL (7121) 3.09 AW 2 bit 9 (programmable Fault Function 30.10)	Motor is operating in stall region due to e.g. excessive load or insufficient motor power.	Check motor load and drive ratings. Check Fault Function parameters.
MOTOR STARTS (FF34)	Motor Identification Run starts. This warning belongs to ID Run procedure.	Wait until drive indicates that motor identification is completed.

WARNING	CAUSE	WHAT TO DO
MOTOR TEMP (4310) 3.08 AW 1 bit 3 (programmable Fault Function 30.04…30.09)	Motor temperature is too high (or appears to be too high) due to excessive load, insufficient motor power, inadequate cooling or incorrect start-up data.	Check motor ratings, load and cooling. Check start-up data. Check Fault Function parameters.
MOTOR 1 TEMP (4312) 3.16 AW 4 bit 1	Measured motor temperature has exceeded alarm limit set by parameter 35.02.	Check value of alarm limit. Check that actual number of sensors corresponds to value set by parameter. Let motor cool down. Ensure proper motor cooling: Check cooling fan, clean cooling surfaces, etc.
MOTOR 2 TEMP (4313) 3.16 AW 4 bit 2	Measured motor temperature has exceeded alarm limit set by parameter 35.05.	Check value of alarm limit. Check that actual number of sensors corresponds to value set by parameter. Let motor cool down. Ensure proper motor cooling: Check cooling fan, clean cooling surfaces, etc.
MOT POW LIM (FF86) 3.18 AW 5 bit 12 (programmable Fault Function 30.23)	Drive limits motor power according to limits defined by parameters 20.11 and 20.12.	Informative alarm Check parameter 20.11 P MOTORING LIM and 20.12 P GENERATING LIM settings. Check Fault Function parameters.
MOT TORQ LIM (FF85) 3.18 AW 5 bit 11 (programmable Fault Function 30.23)	Drive limits motor torque according to calculated motor pull-out torque limit and minimum and maximum torque limits defined by parameters 20.13 and 20.14.	Informative alarm Check parameter 20.13 MIN TORQ SEL and 20.14 MAX TORQ SEL settings. Check Fault Function parameters. If LIMIT WORD 1 bit 0 TORQ MOTOR LIM is 1, – check motor parameter settings (parameter group 99 START-UP DATA) – ensure that ID run has been completed successfully.
PANEL LOSS (5300) 3.09 AW 2 bit 13 (programmable Fault Function 30.02)	Control panel selected as active control location for drive has ceased communicating.	Check panel connection (see appropriate hardware manual). Check control panel connector. Replace control panel in mounting platform. Check Fault Function parameters.
POINTER ERROR (FFD0)	Source selection (pointer) parameter points to non existing parameter index.	Check source selection (pointer) parameter settings.
->POWEROFF! (FF39)	Inverter type (e.g. sr0025_3) has been changed. Inverter type is usually changed at factory or during drive implementation.	Switch control board power off to validate inverter type change.

WARNING	CAUSE	WHAT TO DO
PPCC LINK (5210) 3.06 FW 2 bit 11	Fibre optic link to INT board is faulty.	Check fibre optic cables or galvanic link. With frame sizes R2-R6 link is galvanic. If RMIO is powered from external supply, ensure that supply is on. See parameter 16.09 CTRL BOARD SUPPLY. Check signal 03.19. Contact ABB representative if any of faults in signal 3.19 are active.
PPCC LINK xx	INT board fibre optic connection fault in inverter unit of several parallel connected inverter modules. xx refers to inverter module number.	Check connection from inverter module Main Circuit Interface Board, INT to PPCC Branching Unit, PBU. (Inverter module 1 is connected to PBU INT1 etc.) Check signal 03.19. Contact ABB representative if any of faults in signal 3.19 are active.
(5210)
3.06 FW 2 bit 11 and
4.01
PP OVERLOAD (5482) 3.18 AW 5 bit 5	Excessive IGBT junction to case temperature. This can be caused by excessive load at low frequencies (e.g. fast direction change with excessive load and inertia).	Increase ramp time. Reduce load.
REPLACE FAN (4280) 3.18 AW 5 bit 0	Running time of inverter cooling fan has exceeded its estimated life time.	Replace fan. Reset fan run time counter 01.44.
RUN ENABLE (FF8E) 3.06 FW 2 bit 4	No Run enable signal received.	Check setting of parameter 16.01. Switch on signal or check wiring of selected source.
SLEEP MODE (FF8C) 3.16 AW 4 bit 4	Sleep function has entered sleeping mode.	See parameter group 40 PID CONTROL.
START INHIBI (FF7A) AW 1 bit 0	Safe torque off function has been activated while drive was stopped. Or: Optional start inhibit hardware logic is activated.	Close Safe torque off function switch. If switch is closed and warning is still active, check power supply at ASTO board input terminals. Replace ASTO board. Or: Check start inhibit circuit (AGPS board).
START INTERL (FF8D)	No Start Interlock signal received.	Check circuit connected to Start Interlock input on RMIO board.
SYNCRO SPEED (FF87) 3.18 AW 5 bit 1	Value of motor nominal speed set to parameter 99.08 is not correct: Value is too near synchronous speed of motor. Tolerance is 0.1%. This warning is active only in DTC mode.	Check nominal speed from motor rating plate and set parameter 99.08 exactly accordingly.

WARNING	CAUSE	WHAT TO DO
TEMP DIF xx y (4380) 4.01 FAULTED INT INFO	Excessive temperature difference between several parallel connected inverter modules. xx (1…12) refers to inverter module number and y refers to phase (U, V, W).	Check cooling fan. Replace fan. Check air filters.
	Alarm is indicated when temperature difference is 15°C. Fault is indicated when temperature difference is 20°C.
	Excessive temperature can be caused e.g. by unequal current sharing between parallel connected inverters.
THERMISTOR (4311)	Motor temperature is excessive. Motor thermal protection mode selection is TEMP SENSOR.	Check motor ratings and load. Check start-up data.
3.08 AW 1 bit 2 (programmable Fault Function 30.04…30.05)		Check thermistor connections to digital input DI6.
T MEAS ALM (FF91) 3.08 AW 1 bit 6	Motor temperature measurement is out of acceptable range.	Check connections of motor temperature measurement circuit. See chapter Program features for circuit diagram.
UNDERLOAD (FF6A)	Motor load is too low due to e.g. release mechanism in driven equipment.	Check for problem in driven equipment. Check Fault Function parameters.
3.09 AW 2 bit 1
(programmable Fault Function 30.13)
USER L CURVE (2312) 3.18 AW 5 bit 13	Integrated motor current has exceeded load curve defined by parameters in group 72 USER LOAD CURVE.	Check parameter group 72 USER LOAD CURVE settings. Reduce load.

WARNING	CAUSE	WHAT TO DO
DOWNLOADING FAILED	Download function of panel has failed. No data has been copied from panel to drive.	Make sure panel is in local mode. Retry (there might be interference on link). Contact ABB representative.
DRIVE IS RUNNING DOWNLOADING NOT POSSIBLE	Downloading is not possible while motor is running.	Stop motor. Perform downloading.
NO COMMUNICATION (X)	Cabling problem or hardware malfunction on Panel Link	Check Panel Link connections. Press RESET key. Panel reset may take up to half a minute, please wait.
NO COMMUNICATION (X)	(4) = Panel type not compatible with drive application program version	Check panel type and drive application program version. Panel type is printed on panel cover. Application program version is stored in parameter 33.02.
NO FREE ID NUMBERS ID NUMBER SETTING NOT POSSIBLE	Panel Link already includes 31 stations.	Disconnect another station from link to free ID number.
NOT UPLOADED DOWNLOADING NOT POSSIBLE	No upload function has been performed.	Perform upload function before downloading. See chapter Control panel.
UPLOADING FAILED	Upload function of panel has failed. No data has been copied from drive to panel.	Retry (there might be interference on link). Contact ABB representative.
WRITE ACCESS DENIED PARAMETER SETTING NOT POSSIBLE	Certain parameters do not allow changes while motor is running. If tried, no change is accepted, and warning is displayed. Parameter lock is on.	Stop motor, then change parameter value. Open parameter lock (see parameter 16.02).

FAULT	CAUSE	WHAT TO DO
ACS800 TEMP (4210) 3.05 FW 1 bit 3	Drive IGBT temperature is excessive. Fault trip limit is 100%.	Check ambient conditions. Check air flow and fan operation. Check heatsink fins for dust pick-up. Check motor power against unit power.
ACS TEMP xx y (4210) 3.05 FW 1 bit 3 and 4.01	Excessive internal temperature in inverter unit of several parallel connected inverter modules. xx (1…12) refers to inverter module number and y refers to phase (U, V, W).	Check ambient conditions. Check air flow and fan operation. Check heatsink fins for dust pick-up. Check motor power against unit power.
AI < MIN FUNC (8110) 3.06 FW 2 bit 10 (programmable Fault Function 30.01)	Analogue control signal is below minimum allowed value due to incorrect signal level or failure in control wiring.	Check for proper analogue control signal levels. Check control wiring. Check Fault Function parameters.
AD [message]	Message generated by an EVENT block in the Adaptive Program.	Consult the documentation or author of the Adaptive Program.
BACKUP ERROR (FFA2)	Failure when restoring PC stored backup of drive parameters.	Retry. Check connections. Check that parameters are compatible with drive.
BC OVERHEAT (7114) 3.17 FW 5 bit 4	Brake chopper overload	Let chopper cool down. Check parameter settings of resistor overload protection function (see parameter group 27 BRAKE CHOPPER). Check that braking cycle meets allowed limits. Check that drive supply AC voltage is not excessive.
BC SHORT CIR (7113) 3.17 FW 5 bit 2	Short circuit in brake chopper IGBT(s)	Replace brake chopper. Ensure brake resistor is connected and not damaged.
BRAKE ACKN (FF74) 3.15 FW 4 bit 3	Unexpected state of brake acknowledge signal	See parameter group 42 BRAKE CONTROL. Check connection of brake acknowledgement signal.
BR BROKEN (7110) 3.17 FW 5 bit 0	Brake resistor is not connected or it is damaged. Resistance rating of brake resistor is too high.	Check resistor and resistor connection. Check that resistance rating meets specifications. See appropriate drive hardware manual.

FAULT	CAUSE	WHAT TO DO
BR OVERHEAT (7112) 3.17 FW 5 bit 3	Brake resistor overload	Let resistor cool down. Check parameter settings of resistor overload protection function (see parameter group 27 BRAKE CHOPPER).
		Check that braking cycle meets allowed limits.
		Check that drive supply AC voltage is not excessive.
BR WIRING (7111) 3.17 FW 5 bit 1	Wrong connection of brake resistor	Check resistor connection. Ensure brake resistor is not damaged.
CHOKE OTEMP (FF82)	Excessive temperature of drive output filter. Supervision is in use in step-up drives.	Let drive cool down. Check ambient temperature.
		Check filter fan rotates in correct direction and air flows freely.
COMM MODULE (7510) 3.06 FW 2 bit 12	Cyclical communication between drive and master is lost.	Check status of fieldbus communication. See chapter Fieldbus control, or appropriate fieldbus adapter manual.
(programmable Fault Function 30.18, 30.19)		Check parameter settings: – group 51 COMM MODULE DATA (for fieldbus adapter), or
		– group 52 STANDARD MODBUS (for Standard Modbus Link).
		Check Fault Function parameters.
		Check cable connections.
		Check if master can communicate.
CTRL B TEMP (4110) 3.06 FW 2 bit 7	Control board temperature is above 88°C.	Check ambient conditions. Check air flow. Check main and additional cooling fans.
CURR MEAS (2211)	Current transformer failure in output current measurement circuit	Check current transformer connections to Main Circuit Interface Board, INT.
CUR UNBAL xx (2330)	Drive has detected excessive output current unbalance in inverter unit of several parallel connected inverter modules. This can be caused by external fault (earth fault, motor, motor cabling, etc.) or internal fault (damaged inverter component). xx (1…12) refers to inverter module number.	Check there are no power factor correction capacitors or surge absorbers in motor cable.
3.05 FW 1 bit 4 and 4.01		Check that there is no earth fault in motor or motor cables:
(programmable Fault Function 30.17)		– measure insulation resistances of motor and motor cable. If no earth fault can be detected, contact your local ABB representative.
DC HIGH RUSH (FF80)	Drive supply voltage is excessive. When supply voltage is over 124% of unit voltage rating (415, 500 or 690 V), motor speed rushes to trip level (40% of nominal speed).	Check supply voltage level, drive rated voltage and allowed voltage range of drive.

FAULT	CAUSE	WHAT TO DO
DC OVERVOLT (3210) 3.05 FW 1 bit 2	Excessive intermediate circuit DC voltage. DC overvoltage trip limit is 1.3 × 1.35 × U1max, where U1max is maximum value of supply voltage range. For 400 V units, U1max is 415 V. For 500 V units, U1max is 500 V. For 690 V units, U1max is 690 V. Actual voltage in intermediate circuit corresponding to the supply voltage trip level is 728 V DC for 400 V units, 877 V DC for 500 V units, and 1210 V DC for 690 V units.	Check that overvoltage controller is on (parameter 20.05). Check supply voltage for static or transient overvoltage. Check brake chopper and resistor (if used). Check deceleration time. Use coast-to-stop function (if applicable). Retrofit frequency converter with brake chopper and brake resistor.
DC UNDERVOLT (3220) 3.06 FW 2 bit 2	Intermediate circuit DC voltage is not sufficient due to missing supply voltage phase, blown fuse or rectifier bridge internal fault. DC undervoltage trip limit is 0.6 × 1.35 × U1min, where U1min is minimum value of supply voltage range. For 400 V and 500 V units, U1min is 380 V. For 690 V units, U1min is 525 V. Actual voltage in intermediate circuit corresponding to supply voltage trip level is 307 V DC for 400 V and 500 V units, and 425 V DC for 690 V units.	Check main supply and fuses.
EARTH FAULT (2330) 3.05 FW 1 bit 4 (programmable Fault Function 30.17)	Drive has detected load unbalance typically due to earth fault in motor or motor cable.	Check there are no power factor correction capacitors or surge absorbers in motor cable. Check that there is no earth fault in motor or motor cables: – measure insulation resistances of motor and motor cable. If no earth fault can be detected, contact your local ABB representative.
ENC CABLE (7310) 3.33 FW 6 bit 2 (programmable Fault Function 50.07)	Pulse encoder phase signal is missing.	Check pulse encoder and its wiring. Check pulse encoder interface module and its wiring.
ENCODER A<>B (7302)	Pulse encoder phasing is wrong: Phase A is connected to terminal of phase B and vice versa.	Interchange connection of pulse encoder phases A and B.
ENCODER ERR (7301) 3.06 FW 2 bit 5	Communication fault between pulse encoder and pulse encoder interface module and between module and drive	Check pulse encoder and its wiring, pulse encoder interface module and its wiring and parameter group 50 ENCODER MODULE settings.
EXTERNAL FLT (9000) 3.06 FW 2 bit 8 (programmable Fault Function 30.03)	Fault in external device. (This information is configured through one of programmable digital inputs.)	Check external devices for faults. Check parameter 30.03 EXTERNAL FAULT.

FAULT	CAUSE	WHAT TO DO
FORCED TRIP (FF8F)	Generic Drive Communication Profile trip command	See appropriate communication module manual.
GD DISABLED (FF53)	AGPS power supply of parallel connected R8i inverter module has been switched off during run. X (1…12) refers to inverter module number.	Check Prevention of Unexpected Start-up circuit. Replace AGPS board of R8i inverter module.
ID RUN FAIL (FF84)	Motor ID Run is not completed successfully.	Check maximum speed (parameter 20.02). It should be at least 80% of motor nominal speed (parameter 99.08).
IN CHOKE TEMP (FF81) 3.17 FW 5 bit 5	Excessive input choke temperature	Stop drive. Let it cool down. Check ambient temperature. Check that fan rotates in correct direction and air flows freely.
INT CONFIG (5410) 03.17 FW 5 bit 10	Number of inverter modules is not equal to original number of inverters.	Check status of inverters. See signal 04.01 FAULTED INT INFO. Check fibre optic cables between APBU and inverter modules. If Reduced Run function is used, remove faulted inverter module from main circuit and write number of remaining inverter modules into parameter 95.03 INT CONFIG USER. Reset drive.
INV DISABLED 03.17 FW 5 bit 7 (3200)	Optional DC switch has opened while unit was running or start command was given.	Close DC switch. Check AFSC-0x Fuse Switch Controller unit.
INV OVERTEMP (4290) 3.17 FW 5 bit 13	Converter module temperature is excessive.	Check ambient temperature. If it exceeds 40°C, ensure that load current does not exceed derated load capacity of drive. See appropriate hardware manual. Check that ambient temperature setting is correct (parameter 95.10). Check converter module cooling air flow and fan operation. Cabinet installation: Check cabinet air inlet filters. Change when necessary. See appropriate hardware manual. Modules installed in cabinet by user: Check that cooling air circulation in cabinet has been prevented with air baffles. See module installation instructions. Check inside of cabinet and heatsink of converter module for dust pick-up. Clean when necessary. Reset and restart after problem is solved and let converter module cool down.

FAULT	CAUSE	WHAT TO DO
I/O COMM ERR (7000) 3.06 FW 2 bit 6	Communication error on control board, channel CH1 Electromagnetic interference	Check connections of fibre optic cables on channel CH1. Check all I/O modules (if present) connected to channel CH1. Check for proper earthing of equipment. Check for highly emissive components nearby.
LINE CONV (FF51)	Fault on line side converter	Shift panel from motor side converter control board to line side converter control board. See line side converter manual for fault description.
MOD BOARD T (FF88)	Overtemperature in AINT board of inverter module.	Check inverter fan. Check ambient temperature.
MOD CHOKE T (FF89)	Overtemperature in choke of liquid cooled R8i inverter module.	Check inverter fan. Check ambient temperature. Check liquid cooling system.
MOTOR PHASE (FF56) 3.06 FW 2 bit 15 (programmable Fault Function 30.16)	One of motor phases is lost due to fault in motor, motor cable, thermal relay (if used) or internal fault.	Check motor and motor cable. Check thermal relay (if used). Check Fault Function parameters. Disable this protection.
MOTOR STALL (7121) 3.06 FW 2 bit 14 (programmable Fault Function 30.10…30.12)	Motor is operating in stall region due to e.g. excessive load or insufficient motor power.	Check motor load and drive ratings. Check Fault Function parameters.
MOTOR TEMP (4310) 3.05 FW 1 bit 6 (programmable Fault Function 30.04…30.09)	Motor temperature is too high (or appears to be too high) due to excessive load, insufficient motor power, inadequate cooling or incorrect start-up data.	Check motor ratings and load. Check start-up data. Check Fault Function parameters.
MOTOR 1 TEMP (4312) 3.15 FW 4 bit 1	Measured motor temperature has exceeded fault limit set by parameter 35.03.	Check value of fault limit. Let motor cool down. Ensure proper motor cooling: Check cooling fan, clean cooling surfaces, etc.
MOTOR 2 TEMP (4313) 3.15 FW 4 bit 2	Measured motor temperature has exceeded fault limit set by parameter 35.06.	Check value of fault limit. Let motor cool down. Ensure proper motor cooling: Check cooling fan, clean cooling surfaces, etc.
NO MOT DATA (FF52) 3.06 FW 2 bit 1	Motor data is not given or motor data does not match with inverter data.	Check motor data parameters 99.04…99.09.

FAULT	CAUSE	WHAT TO DO
I/O COMM ERR (7000) 3.06 FW 2 bit 6	Communication error on control board, channel CH1 Electromagnetic interference	Check connections of fibre optic cables on channel CH1. Check all I/O modules (if present) connected to channel CH1. Check for proper earthing of equipment. Check for highly emissive components nearby.
LINE CONV (FF51)	Fault on line side converter	Shift panel from motor side converter control board to line side converter control board. See line side converter manual for fault description.
MOD BOARD T (FF88)	Overtemperature in AINT board of inverter module.	Check inverter fan. Check ambient temperature.
MOD CHOKE T (FF89)	Overtemperature in choke of liquid cooled R8i inverter module.	Check inverter fan. Check ambient temperature. Check liquid cooling system.
MOTOR PHASE (FF56) 3.06 FW 2 bit 15 (programmable Fault Function 30.16)	One of motor phases is lost due to fault in motor, motor cable, thermal relay (if used) or internal fault.	Check motor and motor cable. Check thermal relay (if used). Check Fault Function parameters. Disable this protection.
MOTOR STALL (7121) 3.06 FW 2 bit 14 (programmable Fault Function 30.10…30.12)	Motor is operating in stall region due to e.g. excessive load or insufficient motor power.	Check motor load and drive ratings. Check Fault Function parameters.
MOTOR TEMP (4310) 3.05 FW 1 bit 6 (programmable Fault Function 30.04…30.09)	Motor temperature is too high (or appears to be too high) due to excessive load, insufficient motor power, inadequate cooling or incorrect start-up data.	Check motor ratings and load. Check start-up data. Check Fault Function parameters.
MOTOR 1 TEMP (4312) 3.15 FW 4 bit 1	Measured motor temperature has exceeded fault limit set by parameter 35.03.	Check value of fault limit. Let motor cool down. Ensure proper motor cooling: Check cooling fan, clean cooling surfaces, etc.
MOTOR 2 TEMP (4313) 3.15 FW 4 bit 2	Measured motor temperature has exceeded fault limit set by parameter 35.06.	Check value of fault limit. Let motor cool down. Ensure proper motor cooling: Check cooling fan, clean cooling surfaces, etc.
NO MOT DATA (FF52) 3.06 FW 2 bit 1	Motor data is not given or motor data does not match with inverter data.	Check motor data parameters 99.04…99.09.

FAULT	CAUSE	WHAT TO DO
POWERF INV xx (3381) 3.17 FW 5 bit 9 and	INT board powerfail in inverter unit of several parallel connected inverter modules. xx (1…12) refers to inverter module number.	Check that INT board power cable is connected. Check that POW board is working correctly.
4.01		Replace INT board.
PPCC LINK (5210) 3.06 FW 2 bit 11	Fibre optic link to INT board is faulty.	Check fibre optic cables or galvanic link. With frame sizes R2-R6 link is galvanic. If RMIO is powered from external supply, ensure that supply is on. See parameter 16.09 CTRL BOARD SUPPLY. Check signal 03.19. Contact ABB representative if any of faults in signal 3.19 are active.
PPCC LINK xx	INT board fibre optic connection fault in inverter unit of several parallel connected inverter modules. xx refers to inverter module number.	Check connection from inverter module Main Circuit Interface Board, INT to PPCC Branching Unit, PBU. (Inverter module 1 is connected to PBU INT1 etc.) Check signal 03.19. Contact ABB representative if any of faults in signal 3.19 are active.
(5210)
3.06 FW 2 bit 11 and
4.01
PP OVERLOAD (5482) 3.17 FW 5 bit 6	Excessive IGBT junction to case temperature. This fault protects IGBT(s) and it can be activated by short circuit at output of long motor cables.	Check motor cables.
SC INV xx y	Short circuit in inverter unit of several parallel	Check motor and motor cable.
(2340) 3.05 FW 1 bit 0, 4.01	connected inverter modules. xx (1…12) refers to inverter module number and y refers to phase (U, V, W).	Check power semiconductors (IGBTs) of inverter module.
and 4.02
SHORT CIRC	Short-circuit in motor cable(s) or motor	Check motor and motor cable.
(2340)		Check there are no power factor correction
3.05 FW 1 bit 0 and		capacitors or surge absorbers in motor cable.
4.02
	Output bridge of converter unit is faulty.	Contact ABB representative.
SLOT OVERLAP (FF8A)	Two option modules have same connection interface selection.	Check connection interface selections in group 98 OPTION MODULES.
START INHIBI (FF7A) 3.03 bit 8	Safe torque off has been activated during motor run or motor start command has been given when Safe torque off is active. Or: Optional start inhibit hardware logic is activated.	Close Safe torque off switch. If switch is closed and fault is still active, check power supply at ASTO board input terminals. Replace ASTO board. Or: Check start inhibit circuit (AGPS board).
SUPPLY PHASE (3130) 3.06 FW 2 bit 0	Intermediate circuit DC voltage is oscillating due to missing supply voltage phase, blown fuse or rectifier bridge internal fault. Trip occurs when DC voltage ripple is 13% of DC voltage.	Check main supply fuses. Check for main supply imbalance.

FAULT	CAUSE	WHAT TO DO
TEMP DIF xx y (4380) 3.17 FW 5 bit 8 and 4.01	Excessive temperature difference between several parallel connected inverter modules. xx (1…12) refers to inverter module number and y refers to phase (U, V, W).	Check cooling fan. Replace fan. Check air filters.
	Alarm is indicated when temperature difference is 15°C. Fault is indicated when temperature difference is 20°C
	Excessive temperature can be caused e.g. by unequal current sharing between parallel connected inverters.
THERMAL MODE (FF50)	Motor thermal protection mode is set to DTC for high-power motor.	See parameter 30.05.
THERMISTOR (4311)	Motor temperature is excessive. Motor thermal protection mode selection is TEMP SENSOR.	Check motor ratings and load. Check start-up data.
3.05 FW 1 bit 5 (programmable Fault Function 30.04…30.05)		Check thermistor connections to digital input DI6.
UNDERLOAD (FF6A)	Motor load is too low due to e.g. release mechanism in driven equipment.	Check for problem in driven equipment. Check Fault Function parameters.
3.05 FW 1 bit 8
(programmable Fault Function 30.13…30.15)
USER L CURVE (2312) 3.17 FW 5 bit 11	Integrated motor current has exceeded load curve defined by parameter group 72 USER LOAD CURVE.	Check parameter group 72 USER LOAD CURVE settings. After motor cooling time specified by parameter 72.20 LOAD COOLING TIME has elapsed, fault can be reset.
USER MACRO (FFA1) 3.07 SFW bit 1	No User Macro saved or file is defective.	Create User Macro.

When encountering issues with your ACS800 inverter, it’s essential to follow proper troubleshooting procedures to address the problem effectively. Referencing the “ABB ACS800 troubleshooting manual” can provide invaluable guidance in diagnosing and resolving faults. Here are steps to handle ACS800 inverter faults:

Identify the Fault Code: Upon encountering a fault, the ACS800 inverter typically displays a fault code on the panel display. Refer to the “ABB ACS800 troubleshooting manual” to interpret the specific fault code and understand its implications.
Consult the Troubleshooting Manual: Once you’ve identified the fault code, consult the “ABB ACS800 troubleshooting manual” for detailed instructions on diagnosing and addressing the issue. The manual provides comprehensive troubleshooting procedures tailored to the ACS800 inverter’s specific components and functionalities.
Follow Troubleshooting Steps: Follow the step-by-step troubleshooting steps outlined in the manual to systematically diagnose the fault. The manual offers insights into potential causes of the fault, along with recommended actions to resolve the issue promptly.
Refer to Technical Support: In cases where troubleshooting efforts are unsuccessful or additional assistance is required, don’t hesitate to contact technical support. The “ABB ACS800 troubleshooting manual” serves as a valuable resource for technicians and support personnel, enabling them to provide informed assistance based on the specific fault encountered.
Document and Learn: Throughout the troubleshooting process, document your observations, actions taken, and outcomes. This documentation can serve as a reference for future troubleshooting endeavors and contribute to continuous learning and improvement in managing ACS800 inverter faults.

By adhering to the guidance provided in the “ABB ACS800 troubleshooting manual” and following established troubleshooting procedures, you can effectively address faults encountered with your ACS800 inverter, minimizing downtime and ensuring optimal performance.

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