Overcurrent

What does OC mean?

This fault indicates that the inverter's output current has exceeded its safe operating limit, often due to a sudden increase in motor load, a short circuit in the motor wiring, or rapid acceleration. Excessive current can damage the inverter's power components (IGBTs) and the motor windings if sustained. It triggers a protective shutdown to prevent hardware failure.

• Sudden increase in motor load exceeding the inverter's instantaneous current limit.
• Short circuit detected in motor windings or cabling between the inverter and motor.
• Rapid acceleration time (e.g., Parameter F2-01) set too short for the connected load inertia.
• Motor current sensing circuit malfunction within the inverter leading to false overcurrent detection.
• Incorrect motor tuning parameters (e.g., flux current in vector control) causing excessive current draw.

Click steps to track your progress.

1. 1

   1. Measure motor winding resistance between U-V, V-W, and W-U terminals; ensure readings are balanced within 5% and non-zero.

2. 2

   2. Use a megohmmeter (e.g., 500VDC test voltage) to check insulation resistance between each motor phase (U, V, W) and motor frame ground (PE).

3. 3

   3. Verify the acceleration time parameter (e.g., F2-01) is sufficiently long for the application's load inertia.

4. 4

   4. Inspect inverter output terminals (U, V, W) for any foreign objects, loose connections, or signs of arcing indicative of a short circuit.

5. 5

   5. Monitor motor current using an external clamp meter during operation, comparing peaks to the inverter's rated output current (Parameter P1-01).