Category: Mitsubishi

Posted on by — Leave a comment

LTI Motion ServoC Servo Drive Application Solution for Ceramic Rolling Forming Equipment (Based on Mitsubishi FX-3U Series PLC)

1. Overview
Ceramic rolling forming equipment is a typical multi-axis automatic machine widely used in the initial pressing of electronic, structural, and functional ceramics. The system usually consists of a servo control unit, electrical control system, pneumatic components, and a rolling head. This document introduces in detail how to apply the LTI Motion ServoC series servo drive in combination with the Mitsubishi FX3U series PLC, covering the application strategy, wiring diagram, parameter configuration, and control logic.

ServoCplus

2. Application Scenario and System Structure
This system involves two servo control units:

  • Pressing Axis Servo: Drives the pressing roller vertically to compress ceramic blanks.
  • Rotary Table Servo: Controls intermittent indexing of the rotary table for sequential forming.

3. Key Functional Requirements

  • Precise positioning of the pressing head for consistent product thickness.
  • Indexing rotation of the rotary table with accurate angular control.
  • Multi-sensor interlock with limit switches and origin sensors.
  • Safety integration with emergency stops, alarms, and feedback loops.

4. Hardware and Wiring Configuration

  • PLC: Mitsubishi FX3U-48MR/ES-A
  • Servo Drive: ServoC SGS4.0750.0012.0000.0 (LTI Motion)
  • Motor: Matching LTI servo motor (1.5~2.2kW)
  • Power Supply: 3-phase 400VAC

5. Detailed Servo Wiring
5.1 Pressing Servo (I/O Mode Control)

ServoC TerminalFunctionConnect to PLC
ISD00STR (Forward)Y2
ISD01STL (Reverse)Y3
ENPOEnableY4
DGNDGround0V

5.2 Rotary Table Servo (Pulse + Direction Mode)

ServoC TerminalFunctionConnect to PLC
ME_A+Pulse+Y0
ME_B+Direction+Y1
ENPOEnableY4

5.3 Sensor Inputs

SensorDescriptionConnect to PLC
Origin SensorPressing Axis HomeX3
Bottom SensorPressed PositionX4
Table SensorIndex CompleteX5
LTI MOTION SC54

6. ServoC Parameter Configuration

  • P145 = 4: Position control mode
  • P152 = 1 or 2: Set input mode to pulse+direction or I/O trigger
  • P210 = 2; P211 = 3: Set ISD00 to STR, ISD01 to STL
  • P483 = 2 or 3: Motor direction configuration
  • P759 / P760: Software limit for press upper/lower bounds
  • P803: Position error tolerance

7. Control Logic Sequence

  1. Power ON → Y4 output to enable servos.
  2. Origin detection via X3 → Set M10 (homed flag).
  3. Start pressing:
    • X0 input triggers Y2 = ON (STR), Y3 = OFF (STL).
    • X4 bottom sensor triggers M20.
  4. Return press head:
    • X1 input triggers Y3 = ON (STL), Y2 = OFF.
  5. Rotate table:
    • X2 input + M20 triggers 2000 pulses via Y0 and DIR = Y1.
    • X5 confirms rotation complete (M31).

8. Ladder Diagram (Simplified)

LD M8013
OUT Y4 ; Servo Enable

LD X3
OUT M10 ; Homed flag

LD X0 AND M10
OUT Y2
RST Y3

LD X1 AND M10
OUT Y3
RST Y2

LD X4
OUT M20

LD X2 AND M20
RST M20
SET Y1
PLS Y0 K2000

LD X5
OUT M31
RST M30

9. Diagrams and Application Notes

    ServoC_FX_ConnectionDiagram

    10. Conclusion and Recommendations
    This solution demonstrates the application of ServoC servo drives in high-precision ceramic roller forming machines using Mitsubishi FX3U PLCs.

    Best Practices:

    • Set software travel limits.
    • Implement emergency stops and feedback alarms.
    • Always home the servo before operation.
    • Use opto-isolated I/O to reduce interference.

    Future Extensions:

    • Integrate HMI for parameter recipes and alarms.
    • Add pressure sensors and linear encoders for quality control.
    • Expand to multi-station synchronization with communication protocols.
    Posted on by — Leave a comment

    Mitsubishi FR-A700 Inverter E.ou2 Fault: Analysis and Solutions for Overvoltage During Constant Speed Operation

    Abstract

    This article provides a detailed analysis of the E.ou2 fault (overvoltage during constant speed operation) in the Mitsubishi FR-A700 series inverter. By integrating manual content with real-world application scenarios, it explores the causes, troubleshooting steps, and solutions to help users quickly diagnose and resolve the issue, ensuring stable equipment operation.

    Keywords

    Mitsubishi FR-A700, E.ou2 fault, overvoltage during constant speed, inverter, regenerative energy

    1. Introduction

    The Mitsubishi FR-A700 series inverters are widely recognized for their excellent performance in industrial motor control, particularly in applications like injection molding machines. However, during operation, inverters may trigger fault codes such as the user-reported “E.ou2.” According to the manual and the screenshot provided by the user, E.ou2 indicates an “overvoltage during constant speed operation,” meaning the main circuit DC voltage exceeds a safe threshold during fixed-speed operation, activating the protection mechanism. This article delves into this fault and offers practical solutions.

    E.OU2

    2. Definition and Causes of the E.ou2 Fault

    The E.ou2 fault is a protective error code in the Mitsubishi FR-A700 inverter, specifically denoting “overvoltage during constant speed operation.” When the inverter detects that the main circuit DC voltage surpasses the specified limit (typically related to the power supply voltage and device configuration, e.g., a threshold in a 400V system), it automatically stops output to safeguard the equipment. The primary causes of this fault include:

    • Excessive Regenerative Energy: During constant speed operation, the motor may generate significant regenerative energy due to load characteristics or mechanical inertia, feeding back into the inverter’s DC bus and raising the voltage.
    • Improper Parameter Configuration: For instance, if Pr.22 (stall prevention operation level) is set too low, it may fail to effectively suppress voltage fluctuations.
    • Abnormal Power or Load: Unstable power supply voltage or sudden load changes (e.g., process adjustments in an injection molding machine) may exacerbate regenerative energy production.

    3. Fault Manifestations and Real-World Case

    Based on the user-provided image, the inverter display clearly shows the “E.ou2” error code with the “RUN” light off, indicating that the device has stopped. This issue may occur in the following scenarios:

    • Time Pattern: The user noted that the equipment runs normally in the morning but frequently faults at noon, possibly due to rising environmental temperatures or changes in production load.
    • Industrial Environment: The image reveals dust accumulation on the inverter’s surface, suggesting prolonged operation in a harsh environment, which may impair heat dissipation and worsen the fault.

    4. Troubleshooting and Solutions

    To effectively address the E.ou2 fault, users are advised to follow these step-by-step troubleshooting and improvement measures:

    4.1 Parameter Check and Adjustment
    • Pr.22 (Stall Prevention Operation Level): Verify that this parameter is not lower than the motor’s no-load current. If it is, adjust it to a value higher than the no-load current to prevent erroneous protection triggers.
    • Pr.882 ~ Pr.886 (Regenerative Feedback Function): Enable and optimize these parameters to manage regenerative energy effectively. Refer to page 365 of the manual for specific settings.
    4.2 External Equipment Optimization
    • Braking Unit: If regenerative energy is significant, installing a braking unit to dissipate excess energy through resistors is recommended.
    • Common DC Bus Converter (FR-CV): For frequent overvoltage issues, using an FR-CV can efficiently absorb regenerative energy.
    • Power Supply Inspection: Use a multimeter or oscilloscope to check the input power stability, ensuring voltage fluctuations stay within the inverter’s allowable range.
    4.3 Environmental Improvements
    • Heat Dissipation Management: Ensure proper ventilation for the inverter, adding fans or air conditioning, especially during high-temperature periods (e.g., noon).
    • Cleaning Maintenance: Regularly remove dust from the inverter’s surface to prevent poor heat dissipation from causing cascading issues.
    4.4 Data Logging and Analysis
    • Operation Log: Record data such as load, speed, and environmental temperature at the time of the fault to identify potential patterns.
    • Fault History: Use the inverter’s MON mode to review historical fault records for diagnostic support.
    FR-A700

    5. Case Analysis and Recommendations

    Based on the user’s feedback and image data, the frequent occurrence of the E.ou2 fault at noon may be linked to the following factors:

    • Temperature Impact: Rising environmental temperatures at noon reduce heat dissipation efficiency, making DC bus voltage more likely to exceed limits.
    • Load Fluctuations: Production process adjustments may lighten the load, increasing regenerative energy.
      For this scenario, the following recommendations are suggested:
    1. Enhance heat dissipation measures during high-temperature periods, such as temporarily adding fans.
    2. Investigate load characteristics during noon hours and adjust operating parameters or processes as needed.
    3. Implement regular maintenance to ensure long-term equipment stability.

    6. Conclusion

    The E.ou2 fault is a common overvoltage issue in Mitsubishi FR-A700 inverters during constant speed operation. By optimizing parameter settings, installing external equipment, improving heat dissipation, and conducting regular maintenance, users can significantly reduce fault occurrence and enhance equipment reliability. The troubleshooting steps and solutions provided in this article are universally applicable to similar scenarios.

    7. References

    • Mitsubishi FR-A700 Series Inverter User Manual

    Posted on by — Leave a comment

    User Guide for Mitsubishi FR-A500 (A540 and A520) Series Inverter

    The Mitsubishi FR-A500 series inverter, including models A540 and A520, is a widely used device in the field of industrial control. Its user manual serves as an essential guide for operating and maintaining the inverter. This article provides a detailed introduction to the operation panel functions, parameter settings, password management, external control, and fault handling of this series of inverters based on the user manual.

    FR-A540

    I. Introduction to Operation Panel Functions

    The operation panel (FR-DU04) of the Mitsubishi FR-A500 series inverter is the primary interface for users to interact with the inverter, offering a range of display and operation capabilities:

    • Display Functions: The operation panel can display real-time key parameters of the inverter, such as operating frequency, output current, output voltage, and alarm information, facilitating user monitoring of the inverter’s status.
    • Key Functions:
      • MODE Key: Used to switch between different operation modes, such as monitor mode, frequency setting mode, and parameter setting mode.
      • SET Key: Used to confirm set values or enter the parameter setting interface.
      • ↑ and ↓ Keys: Used to increase or decrease set values, adjusting parameters or frequencies.
      • FWD and REV Keys: Used to issue forward and reverse commands, respectively, controlling the motor’s rotation direction.
      • STOP RESET Key: Used to stop the inverter or reset faults.

    II. Parameter Initialization Settings

    During the use of the inverter, it may be necessary to restore parameters to their factory settings. Users can perform parameter initialization through the following steps:

    • Clear All Parameters: Set parameter Pr.77 to 1, then press and hold the SET key for more than 1.5 seconds to restore all parameters (except Pr.77, Pr.79, Pr.80, and Pr.81) to their factory settings.
    • Clear User Parameter Groups: To clear user-defined parameter groups, use parameters Pr.174 and Pr.176 to clear the first and second user parameter groups, respectively.

    III. Password Setting, Removal, and Parameter Access Restrictions

    To protect the inverter’s parameters from being modified arbitrarily, users can set parameter access restrictions through the following methods:

    • Parameter Write Protection Selection (Pr.77):
      • When set to 1, parameters can only be written when the inverter is stopped.
      • When set to 2, writing to all parameters is prohibited (factory setting).
      • When set to 0, parameter writing is allowed during operation (note: safety considerations apply).
    • Password Function: Although the FR-A500 series inverter does not directly provide a password setting function, parameter write protection through Pr.77 can indirectly achieve a certain level of access control.

    IV. External Control Functions

    The Mitsubishi FR-A500 series inverter supports external terminal control, allowing users to configure it flexibly according to actual needs.

    • External Terminal Forward/Reverse Control:
      • Use terminals STF (forward start) and STR (reverse start) for forward/reverse control. When the STF signal is activated, the inverter operates in the forward direction; when the STR signal is activated, it operates in reverse.
      • Parameter Settings: Ensure that Pr.79 (operation mode selection) is set to external operation mode or combined operation mode to enable external terminal control.
    • External Potentiometer for Frequency Setting and Speed Control:
      • Frequency Setting Terminals: Use terminals 2, 4, 5, and 10 (or AU terminal, depending on parameter settings) for analog frequency setting. Typically, a potentiometer is connected between terminals 10 (or AU) and 5, and the input voltage is adjusted by rotating the potentiometer to set the operating frequency.
      • Parameter Settings: Set Pr.73 to select the voltage input range (e.g., 0-5V, 0-10V, etc.); ensure that parameters such as Pr.125 (analog input filter time constant) are set appropriately to ensure the stability of frequency setting.
    FR-A540

    V. Fault Codes and Handling Methods

    The inverter may encounter various faults during operation, and the user manual provides detailed fault codes and handling methods. Below are some common fault codes and brief handling steps:

    • E.OC1 (Overcurrent Trip During Acceleration): Check if the load is too heavy, if the acceleration time is too short, and if the motor and cable insulation are in good condition.
    • E.OV1 (Regenerative Overvoltage Trip During Acceleration): Check if the power supply voltage is too high, if the deceleration time is too short, and if the braking resistor is damaged.
    • E.THM (Motor Overload Trip): Check if the motor load is too heavy, if the motor cooling is adequate, and if necessary, reduce the load or improve the cooling conditions.
    • E.UVT (Undervoltage Protection): Check if the power supply voltage is too low and if the power lines are properly connected.
    • E.FIN (Heat Sink Overheat): Check if the inverter’s heat sink is excessively dusty, if ventilation is adequate, and if necessary, clean the heat sink or improve ventilation conditions.

    When the inverter stops due to a fault, the operation panel displays the corresponding fault code. Users should refer to the user manual based on the fault code and take appropriate handling measures. After handling, press the STOP RESET key to reset the inverter and restart operation.

    VI. Conclusion

    The Mitsubishi FR-A500 (A540 and A520) series user manual is an essential guide for operating and maintaining the inverter. Through this article, users should be able to master the operation skills of the operation panel functions, parameter initialization settings, password management, external control, and fault handling. In practical applications, users should configure the inverter parameters reasonably according to specific needs to ensure stable and efficient operation of the inverter. Additionally, regularly consulting the user manual to stay informed about the latest features and technical advancements of the inverter is also an important way to enhance equipment management capabilities.

    Posted on by — Leave a comment

    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.

    Posted on by — Leave a comment

    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.

    Posted on by — Leave a comment

    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.

    Posted on by — Leave a comment

    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.