Category: Mitsubishi

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Operation Guide for Mitsubishi VFD FR-D700 （D740,D720）Series User Manual

I. Introduction to VFD Operation Panel Functions
The operation panel of the Mitsubishi VFD FR-D700 series(D740,D720) is straightforward, facilitating various settings and operations for users. The panel primarily includes the following buttons and a rotary potentiometer:

Mitsubishi VFD FR-D700 Operation Panel Function Diagram

RUN: Press this button to start the VFD.
STOP/RESET: Press this button to stop the VFD or reset alarms.
MODE: Mode switching button used to toggle between different setting and display modes.
SET: Confirmation button used to confirm current settings or enter the next menu level.
PU/EXT: Operation mode switching button used to switch between PU (operation panel) mode and EXT (external terminal) mode.
Rotary Potentiometer: Used to manually adjust the output frequency of the VFD.

Setting Operation Modes
The VFD offers multiple operation modes, which can be set via parameter P79:

P79=0: PU operation mode, controlled via buttons and the rotary potentiometer on the operation panel.
P79=2: External operation mode, receiving start, stop, and speed commands via external terminals.

II. Terminal Start/Stop and External Potentiometer Speed Adjustment
Wiring Instructions
To achieve terminal start/stop and external potentiometer speed adjustment, proper wiring to the corresponding terminals of the VFD is required. Typically, the wiring is as follows:

STF (Forward Start): Connect to the normally open contact of an external start button or relay.
STR (Reverse Start): If reverse function is needed, connect to the normally open contact of an external reverse start button or relay.
SD (Stop): Connect to the normally closed contact of an external stop button or relay.
RH, RM, RL (Speed Setting): These terminals are typically used to connect an external potentiometer for speed adjustment. Among them, RH and RL are connected to the two ends of the potentiometer, and RM is connected to the sliding contact of the potentiometer.

Parameter Settings
Apart from proper wiring, relevant parameters need to be set to ensure the VFD operates as expected:

P79: Set to 2 to select external operation mode.
Pr7, Pr8: Set acceleration and deceleration times respectively to suit different application needs.
Pr9: Set the electronic overcurrent protection parameter to protect the VFD and motor from overcurrent damage.

Mitsubishi VFD FR-D700 Series External Wiring Diagram

III. VFD Fault Code Analysis and Solutions
When faults occur in the Mitsubishi VFD FR-D700 series, corresponding error codes are displayed, allowing users to analyze and resolve the faults. Below are some common fault codes and their solutions:

ER1: Overcurrent during acceleration. Check if the motor is overloaded, if there is a short circuit in the output, and if the acceleration time is set too short.
ER2: Overcurrent during constant speed. Check for sudden changes in load, and if there is a short circuit in the output.
ER3: Overcurrent during deceleration. Check for rapid deceleration, if there is a short circuit in the output, and if the motor’s mechanical brake is applied too early.
OL: Overspeed prevention (overcurrent). Check if the motor is overloaded.
TH: Motor overheat. Check if the motor is operating overloaded for a long time, if the ambient temperature is too high, and if the cooling system is functioning properly.
PS: PU stop. Check if the STOP button on the operation panel is pressed.
MT: Main circuit terminal abnormality. Check if the connections of the main circuit terminals are loose or damaged.
uV: Undervoltage protection. Check if the power supply voltage is too low, and if there is a large-capacity motor starting up causing instantaneous voltage drop.

Solutions
For overcurrent faults (ER1, ER2, ER3, OL): First, check if the motor and load are normal, then adjust acceleration time, deceleration time, and electronic overcurrent protection parameters.
For overheating faults (TH): Improve the motor’s cooling conditions, such as adding fans or lowering the ambient temperature.
For PU stop (PS): Confirm if the STOP button was pressed by mistake; if not, check the related control circuits.
For main circuit terminal abnormality (MT): Check and tighten the connections of the main circuit terminals, and replace if damaged.
For undervoltage protection (uV): Check if the power supply voltage is stable, and consider adding a power supply voltage stabilizing device.

The above is the operation guide for the Mitsubishi VFD FR-D700 series user manual, hoping to assist users in practical operations. If encountering other issues during use, it is recommended to refer to the detailed user manual of the VFD or contact professional technicians of longi for consultation.

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Analysis of PLC-Based Variable Frequency Constant Pressure Water Supply System with One-to-Two Drive

Introduction

Variable frequency constant pressure water supply systems are essential for maintaining stable water pressure in pipeline networks. This article delves into a specific system configuration that employs a Programmable Logic Controller (PLC) and a frequency converter to control two water pumps in a one-to-two drive setup. The system ensures continuous and stable water supply by automatically adjusting the pump operations based on pipeline pressure.

Mitsubishi PLC Constant Pressure Water Supply Circuit Diagram

System Overview

The system primarily consists of a frequency converter, a PLC, and two water pumps. The control mechanism leverages the PID (Proportional-Integral-Derivative) and other related functions of the frequency converter, in conjunction with the PLC, to achieve automatic constant pressure water supply. Additionally, the system is equipped with an automatic/manual switching function, allowing manual control of the water pumps in case of a frequency converter fault.

Control Process

The control process of the system is as follows:

  1. Initial Start-Up: When the pipeline pressure drops below the set value, the frequency converter starts the first pump (#1 pump).
  2. Full Speed Operation: After running at full speed for a predetermined period, if the pipeline pressure still does not reach the set value, the PLC switches the #1 pump from frequency conversion to power frequency operation.
  3. Second Pump Activation: The frequency converter then starts the second pump (#2 pump), adjusting its speed based on the pipeline pressure to maintain constant pressure.
  4. Pump Switching: As water demand decreases and pipeline pressure increases, if the #2 pump’s speed drops to zero but the pipeline pressure remains high, the PLC stops the #1 pump operating at power frequency, allowing the #2 pump to maintain constant pressure.
  5. Cycle Continuation: When the pipeline pressure drops again, the #2 pump is switched to power frequency operation, and the frequency converter starts the #1 pump, adjusting its speed to maintain constant pressure. This cycle continues indefinitely.

Frequency Converter Settings

For the system to function correctly, the frequency converter must be configured with specific parameters:

  • Start/Stop Control: Set to operate on external terminals.
  • Parking Mode: Configured for free parking to avoid impact during frequency conversion/power frequency switching.
  • PID Mode: Enabled, with the pressure setting value entered via the AUX terminal and the feedback signal entering via the VIN terminal.
  • Control Terminals: Configured to output contact actions for frequency conversion faults, zero speed, and full speed.
Mitsubishi PLC Constant Pressure Water Supply Program Diagram 1
Mitsubishi PLC Constant Pressure Water Supply Program Diagram 2
Mitsubishi PLC Constant Pressure Water Supply Program Diagram 3
Mitsubishi PLC Constant Pressure Water Supply Program Diagram 4

PLC Control Wiring and Program

The PLC control wiring diagram shows the integration of fault signals from the water pumps and frequency converter, summarized through relay KA2. The manual/automatic switching is controlled by relay KA1, while the frequency conversion/power frequency operation is interlocked via contactor contacts for enhanced safety.

The PLC program is straightforward, consisting of four main steps (S20 to S23) that form a complete cycle. The switching time between frequency conversion and power frequency is adjustable via two potentiometers (D8030 and D8031) connected to the FX1S type PLC.

The program utilizes step instructions combined with set and reset commands. Step control begins with the STL instruction, and upon completion of all steps, a RET instruction returns the program to the starting step (S0). The SET command energizes the coil, while the RST command de-energizes it. The ZRST command is used for batch resetting multiple coils.

Technological Advancements and Alternative Solutions

As technology progresses, frequency converters are becoming more advanced, with some models capable of one-to-three or even one-to-six configurations. Automated instruments can also perform the PID function, allowing the frequency converter to work passively. In some setups, the frequency converter drives only one pump in a fixed manner, with the second pump directly switched to power frequency when needed. This approach, combined with timely pressure regulation by the frequency converter, results in more stable pipeline pressure.

Conclusion

The PLC-based variable frequency constant pressure water supply system with a one-to-two drive is a reliable and efficient solution for maintaining stable water pressure in pipeline networks. By leveraging the capabilities of PLCs and frequency converters, the system automatically adjusts pump operations to meet changing water demands. As technology continues to evolve, alternative solutions and configurations will emerge, offering even greater flexibility and efficiency in water supply management.

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n-depth Analysis and Maintenance Guide for Mitsubishi F1S Switching Power Supply

In-depth Analysis and Maintenance Guide for Mitsubishi F1S Switching Power Supply

In the field of modern industrial automation, the application of Mitsubishi PLCs (Programmable Logic Controllers) is extensive. As a critical component of PLCs, the stability and reliability of the switching power supply directly determine the operating efficiency of the entire system. This article takes the Mitsubishi F1S switching power supply as an example, deeply analyzing its circuit structure, working principle, and maintenance methods. The aim is to provide readers with a comprehensive and practical technical guide.

I. Overview of Circuit Structure

The Mitsubishi F1S switching power supply board is designed intricately, featuring two relatively independent 24V output structures (although somewhat isolated by L2, they can still be considered as two separate outputs). These two outputs not only provide stable 5V power supply for the PLC motherboard but also offer DC24V external control power for external measurement instruments and other devices. The power board is tightly connected to the motherboard through copper needle-shaped rigid wires, ensuring stable signal transmission.

II. Detailed Explanation of Working Principle

  1. Input Filtering and Protection: After entering the power board through the L and N terminals of the PLC, the industrial frequency 220V power first passes through a bidirectional low-pass filter network composed of C1, C2, C4, and L1. This design effectively filters out high-frequency interference and improves the purity of the power supply. Meanwhile, the bidirectional filters L1 and L2 further isolate high-frequency interference pulses from both inside and outside the power supply, ensuring stable system operation. F1 serves as an overload protection fast-acting fuse, while TH1 acts as a temperature fuse, together constituting a dual protection mechanism for the power supply.
  2. Rectification and Oscillation: The filtered AC power passes through F1 and TH1 into the full-wave rectification circuit, where it is rectified to obtain a direct current voltage of approximately 280V. This voltage is sent to the oscillation and voltage-stabilizing circuit centered on STRG6551. STRG6551 is a power oscillation module with an integrated switching tube. Its 4 and 3 pins are the power supply terminals, while 1 and 2 pins are internally connected to the source and drain of the power switching tube. Additionally, pin 2 provides negative feedback for the switching operating current. Pin 5 is the feedback voltage input terminal, used to regulate the stability of the output voltage.
  3. Voltage Stabilization and Protection: The voltage induced by the secondary winding of the switching transformer TB1 undergoes rectification and filtering before serving as the working power for the PLC. To maintain voltage stability, the system employs an output voltage sampling circuit composed of R9, IC2, PC1, and other components. When the voltage changes, this change is converted into a variation in the input current on the PC1 optocoupler device, which is then fed into pin 5 of STRG6551 through R4. The comparison amplification circuit inside STRG6551 adjusts the conduction/cutoff time of the switching tube, i.e., controls the duty cycle of the oscillation frequency, to achieve stable output voltage.

Furthermore, the system boasts a comprehensive protection mechanism. When an abnormal load causes a sharp increase in current, the voltage variation across the sampling resistor R2 is introduced into pin 5 of STRG6551, reducing the output voltage to decrease the load current. When the voltage or current anomaly reaches a certain threshold, STRG6551 disconnects the driving circuit of the switching tube, causing the circuit to oscillate and protecting the subsequent circuit from damage.

III. Maintenance Methods and Practices

Faced with potential faults in the Mitsubishi F1S switching power supply, reasonable troubleshooting steps and scientific maintenance methods are crucial for improving maintenance efficiency. Here are some common maintenance methods:

  1. Routine Inspection: First, check whether the F1 and TH1 fuses are blown. If they are blown and there are no abnormal short-circuit points in the switching tube and load circuit, replacing the fuses generally resolves the issue. If the power still does not oscillate after replacing the fuses, further investigation is needed.
  2. Identify Fault Circuits: Disconnect the PLC motherboard, use a voltage regulator to adjust the input voltage to below AC100V, and connect a dummy load (such as a 100Ω 5W resistor). Short-circuit pins 1 and 2 of the PC1 optocoupler to make the voltage feedback signal zero. Power on and observe the power output. If there is output but not at a stable voltage, the fault lies in the voltage-stabilizing circuit; if there is no output, the fault is in the oscillation circuit.

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Testing Method for Offline Operation of Mitsubishi MR-J3 Servo Driver Maintenance Board

When repairing Mitsubishi servo drives, encountering damaged modules is common. After repairing such modules, it’s crucial to test the drive board’s output function offline before reinstallation. This article provides a detailed guide for testing a repaired Mitsubishi MR-J3-350A/3.5KW servo module.

Mitsubishi Servo MR-J3 Circuit Board Maintenance Test Diagram

Preparation for Offline Testing:

  1. Power Connection: Connect 300V DC voltage to power boards P2 and N to avoid E9 fault after power-on.
  2. Module Pad Hole Shielding:
    • Connect the 10 pins of the module pad hole to N.
    • Connect pad holes U, V, W to N to prevent AL24 fault.
    • Connect pad holes EV, EU, EW (upper axle drive trigger) to N.

Parameter Setting Before Running:

  1. Change PA01: Set PA01 to 0002.
  2. Change PD01: Set PD01 to 0000.
  3. Power Board Connection: Connect P and D on the power board.
  4. Additional Power Board Connections: Connect L1 to L11 and L2 to L12 on the power board.
    • If PD parameters are not visible, change PA19 to 000C and power on again.
Mitsubishi servo MR-J3 drive circuit actual pulse state

Testing Process:

  • After following the above steps, power on and run the servo to test its 6-way waveform.
  • During parameter waveform testing, manually rotate the motor shaft to observe changes in pulse width and phase in the waveform. Note that this machine does not have a static cut-off negative voltage.

By following this comprehensive guide, you can effectively test the offline operation of a repaired Mitsubishi MR-J3 servo driver maintenance board, ensuring its functionality before reinstallation.