Applicable Systems
WJ200
Symptoms
The WJ200 reports an overspeed fault. The motor speed exceeded the overspeed threshold, indicating loss of speed control.
Possible Causes
- Speed command exceeding the motor rated maximum speed
- Load runaway due to gravity or external force overpowering the brake
- Speed feedback signal error causing false overspeed detection
Troubleshooting Steps
- Step 1: Check the speed command source for excessive values in the drive
Speed command is within the valid range - Step 2: Verify the brake is holding when the motor is stopped
Brake holds the load without slipping - Step 3: Check the encoder signal for noise or missing pulses
Encoder signal is clean and accurate
How to Reset
To reset: Reduce speed to within limits, then reset the fault.
Source: Hitachi WJ200 Inverter Manual, Hitachi Industrial Equipment
Category: PLC & VFD