Overcurrent trip during constant speed

What does E.OC2 mean?

This fault indicates that the inverter's output current has reached or exceeded approximately 200% of its rated value while operating at a constant speed. This is typically caused by sudden increases in mechanical load, a short circuit, or a ground fault in the motor or its cabling. Persistent overcurrent can lead to overheating and premature failure of inverter components.

• Sudden mechanical overload or jamming event in the driven process during normal operation.
• Fluctuations in the driven load, such as material blockages or sudden increases in viscosity.
• Motor insulation breakdown or internal winding short circuit occurring during operation.
• Inverter current sensing circuit malfunction, providing erroneous high current readings.
• Excessive regeneration from the load (e.g., hoist lowering) exceeding braking resistor capacity (Pr. 10 setting).

Click steps to track your progress.

1. 1

   Disconnect main power supply to the inverter and wait for DC bus discharge (measure terminal V+/V- for 0VDC).

2. 2

   Inspect the mechanical system for any signs of binding, obstructions, or sudden load changes during operation.

3. 3

   Disconnect the motor cables (U, V, W) from the inverter output terminals.

4. 4

   Using a clamp-on ammeter, measure current draw on each phase (U, V, W) when the motor is running at constant speed (if possible, with external power source).

5. 5

   Check if the motor's operating current displayed on the inverter (e.g., Pr. 02) closely matches actual motor nameplate current at full load.

6. 6

   Verify output voltage balance on inverter terminals U, V, W using a multimeter while running with a motor.