Tag: Siemens VSD

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Siemens MM430 VSD 7.5kW power supply hiccup fault

Repair an imported Siemens 7.5kW frequency converter due to power supply hiccup fault, with no display on the operation panel. Due to its special installation structure, the machine is surrounded by three circuit boards and a heat dissipation plate in a square shape, with an embedded shell. When repairing, it is necessary to disconnect the circuit board and lay the entire circuit flat on the workbench, such as unfolding a roll of ancient bamboo slips, in order to facilitate maintenance. Moreover, the circuit board is a four layer board, making circuit maintenance difficult.

Starting from the switch power supply circuit, first use the elimination method to cut off the load circuit one by one. If it still cannot vibrate well, it indicates that hiccups are not caused by excessive load. There are no abnormalities in the oscillation and voltage stabilization circuits. Finally, it was found that two 200V voltage stabilizing tubes in the cut-off shunt circuit of the switch tube were damaged due to breakdown. We purchased 110V voltage stabilizing tubes from the market and replaced them with four to repair them. A typical shunt (also known as anti peak voltage absorption) circuit uses a diode connected in series with a resistance capacitance parallel circuit, and then connected in parallel with the primary winding of a switching transformer. The diode connection method is similar to the freewheeling diode connection method of a typical coil circuit. Its function is to quickly release the electrical energy of the primary winding circuit during the period when the switching transistor is approaching cutoff, so that the switching transistor can cut off more quickly. But the circuit consists of two 200V voltage regulators connected in series from the P+end, followed by two thermistors with resistance values of 360k each, connected in series to the drain of the switching tube. The circuit is also connected in parallel to the primary winding. When the switch tube tends to cut off, the sharp decrease in current in the primary winding causes a sharp increase in the back electromotive force of the winding. When it is superimposed with the power supply voltage and exceeds the P+voltage by 400V, this protective circuit breaks down and conducts, releasing this energy back to the power supply. When the back electromotive force energy is small, the current flowing through the two thermistors is small, their temperature rise is also small, their resistance value is large, and the release of energy is also slow. When the back electromotive force energy is large, as the discharge current increases, the resistance temperature rises, the resistance value decreases, and the energy discharge is accelerated. Think about it, this circuit is connected in series with a thermistor, it’s really interesting. Adding a thermistor and a peak voltage absorption circuit with voltage stabilizing diodes to the primary winding of the switch transformer may only be done by Siemens frequency converters. I have also encountered this type of circuit form for the first time.

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Debugging of Siemens 400 series 420/430/440 VFD drive

For those who are debugging Siemens frequency converters for the first time, the unfamiliar signs and thousands of parameters listed on the operation panel can be as thick as several hundred
The instruction manual on the page feels a bit dizzy. Adjust the two commonly used quantities for frequency converters – frequency source and operating instructions – to
It is said that besides being able to quickly search in the “Quick Debugging” mode, such as flipping through the parameter table, as the relevant parameters are not in the same place as other frequency converters, it takes a long time to search back and forth.
Is there a simple way to quickly achieve these two functions in conventional applications, such as using the operation panel to start/stop and frequency adjustment
What about the regulation? Sure! And don’t change the control mode by changing the parameters like other frequency converters. Instead, press the two keys on the operation panel to complete the switch between the two control modes. From this point on, the operation and control of Siemens frequency converters are extremely simple. The debugging steps are as follows (taking the 430 frequency converter as an example):

  1. Refer to the above figure and connect the terminal wires properly. There are five wires that need to be connected: connect a start/stop switch between terminals 5 and 9
    Close; Short circuit terminals 2 and 4 first, then connect three wires from terminals 1, 3, and 4 to a potentiometer for frequency adjustment
    Whole. Note that terminal 3 is connected to the center head of the potentiometer. All control lines have been connected.
  2. Let’s learn about the key position functions on the control panel:

Panel appearance

These two keys are the start and stop keys for panel operations. Marked as 1 and 0, not as RUN and STOP.

These three keys are parameter adjustment keys. P is the key for entering parameters and storing confirmation, which is equivalent to the combination of the conventional function/data (DRIVE/PRGM and DATA/ENTER) keys and data writing keys. That is, use the P key to enter the parameter adjustment mode, use the up and down arrows to call up the required adjusted parameters, use the P key to confirm, use the up and down arrows to adjust their values, and still use the P key to write the parameters.

Press this button for 2 seconds during operation to display operating data such as speed, current, voltage, etc; Can be used as the return key after parameter adjustment is completed; Can be used as a reset button for fault shutdown. When adjusting parameters, it can also be used as a shift key. Don’t worry about it for now.

There are still two keys left that have not been explained. These are two important shortcut control keys, which are the switch keys for operating panel control and terminal control. The Hand key is defined as a “manual key” in the manual, which means to use the operation panel to operate locally, perform start/stop and frequency adjustment; The Auto key is defined as “Auto key” in the manual, which means operating with terminal leads outside the machine. After pressing the Hand key, the corresponding characters will appear on the LCD screen. You can operate the 1 and 0 keys to start/stop control, and use the arrow keys to adjust the frequency. After pressing the Auto key, the corresponding characters will appear on the LCD screen, and terminal wiring can be used for operation and control.

  1. For newly manufactured machines, there is no need to adjust the parameters. Once you understand the button functions and connect the terminals properly, you can put them into operation. but
    One of the simplest methods for used machines is to initialize all parameters and restore them to their factory values, and then they can run normally.
    Parameter initialization requires setting two parameter values: 1. Set P0010=30; 2. Set P0970=1.
    Attention! After entering the parameter values, the flashing busy four character display will be displayed, and the reset process will take about three minutes to complete.
    Okay, as long as you remember the 5 wires and understand the button functions on the operation panel, remember the two initialization parameter values, even if you don’t have them on hand
    The manual for the frequency converter, you can also solve the problem immediately on site!
    2、 PID operation adjustment (440)
    Related parameters for PID single machine operation:
    P2200=1, PID function enabled, acceleration and deceleration time, and conventional frequency settings disabled.
    P2253 PID setting signal source selection, P2253=755: analog input 1; P2253=2224: Fixed frequency setting
    The value can be set in P2201 to P2207, the same as the fixed frequency setting and application. Directly select the PID fixed frequency setting value P2201 through DIN1 (terminal 5). And so on;
    P2264 PID feedback signal selection, P2264=755: analog input 1; P2264=2224: Fixed frequency setting
    For the multi machine operation mode of PID one variable frequency and three power frequencies, detailed adjustments must be made according to the manual.
    3、 Shortcuts and precautions for parameter adjustment
    Ordinary parameters for simple operation can be directly adjusted. To adjust PID parameters, P003 needs to be set to 3. P0003=0 user-defined parameter table; P0003=1 standard level parameter; P0003=2 extension level parameter; P0003=3 expert level parameters;
    P0003=4 maintenance level parameter;
    If there are specific parameters that need to be set elsewhere, the value of P004 should be changed. For example, to adjust the frequency setting value P1000 and related parameters, P0004=10 needs to be set. There is a parameter overview diagram in the manual for reference.

Definition and setting of digital terminal function, command source P700=2, for digital input control.
P701 (terminal 5/digital input 1), P702 (terminal 6/digital input 2), P703 (terminal 7/digital input 3)
P704 (terminal 8/digital input 4), P705 (terminal 16/digital input 5), P707 (terminal 17/digital input 6):
The definition of its numerical value is: 1. Forward running; 2. Reverse operation; 3. Inertia parking (free parking); 12. Reverse operation;

  1. Fault reset; 15. Fixed frequency, i.e. multi-stage speed.
    Set one of the terminals to 12, and after reverse operation, set parameter P0010 (frequency setting value that prohibits reverse) to 0 at the same time,
    Only allowed to run in reverse! Adjust P1820, output phase sequence reverse, invalid.
    Frequency setting value P1000
    Set a certain digital terminal to 15- after running at a fixed frequency/multi speed, P1000=33 must be adjusted simultaneously, which means analog signal 1+fixed frequency. After disconnecting terminal 3 and simulating the given value, the digital terminal set to 15 is connected to operate in fixed frequency mode. For example, after setting terminal 7 to 15, first connect terminals 5 and 9 to give the operating signal, and then connect terminals 7 (digital terminals 3) and 9. The frequency converter will operate according to the fixed frequency value P1005. Connect terminal 8, and the frequency converter will operate according to the fixed frequency value P1007.
    Set P1000 to 3, and after fixing the frequency, terminals 7 and 8 will operate according to the frequency values in P1003 and P1004. Meanwhile, analog signal 1 is invalid.
    V/F curve adjustment P1300 P1300=1, constant torque load for transport aircraft; P1300=2, increasing the torque square of dynamic response
    Equation; P1300=2, variable torque load for fans and pumps; P1300=5, textile machinery and other constant power loads; The adjustment of the upper and lower limits of acceleration and deceleration time and frequency is adjusted by four parameters: P1120, P1121, P1082, and P1080.
    4、 The control and wiring of inertial (free) parking, for example, first set P701=1 for “forward start/stop” control, and then set P702=3 for “inertial parking” control,
    After connecting terminals 5 and 6 in parallel, connect terminal 9 for forward running, and disconnect terminal 9 for free parking control. External control
    There are still 2 wires. This is a method. When the frequency converter is used for constant pressure water supply, for the operation of a single frequency converter, the deceleration parking method is adopted
    It can effectively reduce the “water hammer effect”, but for the one to several mode operation, the free parking mode must be changed! Otherwise, due to carrying load
    Switching causes module damage due to impact.
    For Siemens high-power frequency converters, it is also important to note that when starting a high-power motor for the first time, a certain excitation current should be output
    After starting the frequency converter with a certain excitation time, the motor emits a buzzing sound but cannot operate. It’s not a malfunction. After a few seconds,
    The excitation action is completed before the motor starts running. The purpose of this excitation function is to magnetize the stator winding of the motor before starting,
    Increase its inductance to reduce the starting current of high-power motors.
    The debugging in this article is mostly applicable to 420/430/440 frequency converters and can be used as a reference.