Yaskawa OC: Yaskawa A1000 Error Code OC

Symptoms

The drive trips immediately. The digital operator displays OC, indicating an overcurrent condition. The drive output current has exceeded the trip threshold, typically 200% or more of rated current.

Possible Causes

Short circuit in motor cables or motor windings
Sudden load increase beyond drive torque capacity
Ground fault on the motor output
Drive IGBT module failure

Troubleshooting Steps

Step 1: Inspect motor cables for insulation damage
Cable insulation is intact, no shorts between phases or to ground
Step 2: Megger the motor windings phase-to-phase and to ground
Motor insulation resistance is within acceptable limits
Step 3: Verify motor parameters (FLA, voltage, power, RPM) match the nameplate
Parameters match the motor nameplate exactly
Step 4: If no external cause is found, the drive IGBT module may be shorted
Drive needs service if output short is internal

How to Reset

To reset: 1) Fix the cause (cable short, motor fault, parameter error). 2) Press RESET. Caution: Do not repeatedly reset an OC fault without fixing the root cause. Repeated overcurrent trips can permanently damage the drive IGBT module.

Common Replacement Parts

CDBR-0045: Yaskawa dynamic braking resistor (Required for fast deceleration to prevent overvoltage)

Frequently Asked Questions

Q: What causes instantaneous overcurrent in a VFD?
Common causes include shorted motor cables, motor winding shorts, ground faults, sudden load changes, IGBT module failure, or incorrect motor parameter settings causing the drive to command excessive current.
Q: How do I test for a motor short circuit?
Use a megohmmeter at 500V to measure insulation resistance between each phase and ground, and between each pair of phases. Healthy motors show megohm-range resistance. Low or zero readings indicate a short.

Yaskawa A1000 Error Code OC