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

The specific variant tells you when in the cycle the overcurrent occurred, which helps identify the cause.

Jump to Fix

• Most Likely Cause
• Diagnosis Steps
• Parameters

Common Causes {#most-likely-cause}

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

Replacement Parts

Technician Tips

When diagnosing VFD faults, always check the drive’s fault history before resetting. Modern drives store the last 5-10 faults with the drive state at the time (running, accelerating, decelerating, stopped). An overcurrent fault that occurs only during acceleration points to incorrect motor data or mechanical binding. The same fault during deceleration suggests regeneration issues. A ground fault that clears after disconnecting the motor and returns when reconnected means the motor or cable insulation has failed.

Prevention: Schedule annual infrared scanning of drive cabinets. Loose power connections and failing capacitors produce heat long before they cause faults. A 5-minute scan can prevent hours of unplanned downtime.

Need Replacement Parts?

Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.

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.

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