I²t overload

What does OC5 mean?

This fault indicates an I²t overload condition, meaning the motor or drive has experienced excessive current over an extended period, leading to thermal stress. By default, it triggers a full TRIP, inhibiting all ignition pulses for both armature and field circuits and resetting the Ready signal. This protective action prevents components from overheating and potential damage, requiring manual reset after the fault is cleared.

• Motor operating continuously above its rated current due to excessive mechanical load on the driven equipment.
• Drive's motor thermal model (e.g., P0-03 motor rated current, P1-54 I2t trip level) is incorrectly configured for the connected motor.
• Insufficient cooling of the motor itself, leading to faster thermal accumulation even with acceptable current.
• Prolonged acceleration or deceleration times (e.g., P1-03, P1-04) for heavy loads, causing high RMS current.
• Harmonic distortion in the motor current, causing additional heating not accounted for by simple RMS current measurement.

Click steps to track your progress.

1. 1

   Measure the actual RMS current drawn by the motor in all three phases during operation and compare to the motor's nameplate rated current and drive parameters (P0-03).

2. 2

   Verify the motor's thermal parameters (e.g., P0-03, P0-04, P0-05) in the drive match the actual motor data sheet.

3. 3

   Inspect the driven machinery for mechanical binding or excessive friction (e.g., seized bearings, misaligned couplings).

4. 4

   Check the motor's ventilation and ensure no obstructions; measure motor housing temperature during operation.

5. 5

   Consider increasing acceleration/deceleration ramps (P1-03, P1-04) if transient currents are causing the fault, provided the application allows.

6. 6

   If available, review the drive's internal I²t counter (e.g., P1-50) to see how close it was to the trip threshold before the fault.