Overcurrent during Deceleration

What does E.OC3 mean?

The inverter output current has exceeded approximately 230% of its rated value during deceleration, causing the protection circuit to activate and shut off the inverter. This can be caused by sudden speed reductions, an output short-circuit, or issues with the mechanical brake. Unresolved, it can lead to component stress and potential damage.

• Rapid deceleration time (e.g., Pr.7 Acceleration/Deceleration time 2) set too short, causing excessive regenerative energy.
• Motor load inertia significantly exceeds the inverter's capacity, leading to high current demand during deceleration.
• Mechanical binding, excessive friction, or a sudden load increase on the motor during deceleration.
• Internal inverter IGBT short-circuit or a motor phase-to-phase short causing excessive output current.

Click steps to track your progress.

1. 1

   1. Measure motor winding resistance (U-V, V-W, W-U) to verify balanced values and check for short circuits (expected: < 1 Ohm for typical motors).

2. 2

   2. Increase the deceleration time (Pr.7 or Pr.28) by 20-50% to reduce the regenerative energy impact on the DC bus.

3. 3

   3. If applicable, verify external braking resistor unit is installed and parameters Pr.30 (Braking operation frequency) and Pr.70 (Braking duty factor) are correctly configured.

4. 4

   4. Disconnect the motor from the load and manually rotate the mechanical system to check for binding, excessive friction, or obstructions.

5. 5

   5. Check for short circuits between inverter output terminals (U, V, W) and ground using a multimeter (expected: infinite resistance).