Yaskawa V1000 Fault OC — Overcurrent
The OC fault on the Yaskawa V1000 compact inverter drive means the drive’s output current has exceeded the overcurrent trip level — approximately 200% of the drive’s rated current for an instantaneous trip. The drive shuts down immediately to protect the output transistors and motor.
V1000 OC Fault Variants
| Fault Code | Description |
|---|---|
| OC | Overcurrent — general |
| OCA | Overcurrent during acceleration |
| OCb | Overcurrent during deceleration |
| OCC | Overcurrent during constant speed |
| OC | Overcurrent at stop or startup |
The specific variant tells you when in the cycle the overcurrent occurred, which helps identify the cause.
Jump to Fix
Common Causes {#most-likely-cause}
| Cause | Fault Type | Likelihood |
|---|---|---|
| Acceleration ramp too short | OCA | Very High |
| Motor stall (mechanical load jam) | OCC | High |
| Deceleration ramp too short | OCb | High |
| Short circuit in motor cable | OCA/OCC | Medium |
| Failed output IGBT | OCA | Medium |
| V/f profile mismatch for motor | OCA | Medium |
| Ground fault on motor or cable | OCA | Medium |
| Motor too small for load | OCC | Low |
Step-by-Step Diagnosis {#diagnosis}
Step 1 — Identify the fault variant
- OCA (during acceleration): usually a ramp time or motor parameter issue
- OCb (during deceleration): usually ramp too short; try increasing deceleration time
- OCC (constant speed): usually mechanical overload or stall
- OC at startup: may indicate short circuit — immediately check motor and cable
Step 2 — Extend acceleration ramp (if OCA)
- V1000 Parameter C1-01 (Acceleration Time 1): increase by 25–50%
- Default is 10 seconds — try 20 seconds and see if OCA clears
Step 3 — Check for mechanical jam
- If the motor shaft cannot turn freely: check driven equipment for binding, seized bearings, or jam
- With power off, manually rotate the load — it should turn freely
Step 4 — Megger test motor and cable
- With drive output disconnected, megger from each phase to ground
- Below 1 MΩ: insulation failure — replace motor or cable
- This rules out a fault caused by ground leakage being misread as overcurrent
Step 5 — Check the V/f setting
- Incorrect V/f settings cause excessive magnetizing current
- V1000 Parameter E1-01 through E1-13: verify input voltage and motor base frequency match motor nameplate
- Running at full voltage before the motor reaches base speed causes OCA
Step 6 — Check drive output transistors
- With the motor disconnected and power off (wait 5 minutes for bus discharge):
- Measure from U, V, W output terminals to DC+ and DC- with a multimeter on diode test
- A healthy IGBT shows one-way diode drop; a short in either direction = failed IGBT
Key V1000 Parameters for OC Faults
| Parameter | Function | OC-Related Setting |
|---|---|---|
| C1-01 | Acceleration Time 1 | Increase if OCA fault |
| C1-02 | Deceleration Time 1 | Increase if OCb fault |
| L3-04 | Stall Prevention — constant speed | Adjust for heavy loads |
| E1-01 | Input voltage setting | Must match actual supply |
| L3-02 | Stall Prevention — acceleration | Enable for variable loads |
Replacement Parts
| Part | Notes |
|---|---|
| Yaskawa V1000 drive | Amazon | If output IGBT is shorted |
| Motor | Amazon | If winding insulation failed |
| Motor cable | Amazon | Use shielded cable — 4-conductor VFD-rated |
Pro tip: The Yaskawa V1000 supports online auto-tuning (parameter T1-01 = 2 for rotational auto-tune). Running auto-tune after a motor change or OC fault helps the drive learn the correct motor parameters and reduces OC trips.