Current Offset Fault

What does CoF mean?

A Current Offset Fault occurs when the drive attempts to start operation while residual induced voltage is still present in the motor, such as after coasting to a stop or rapid deceleration. This indicates the current offset value has exceeded its permitted automatic adjustment range. In rare cases, this fault may also point to an internal hardware problem within the drive itself. Failure to resolve this can lead to incorrect motor control, erratic startup behavior, or potential damage if a hardware issue is present.

• Motor current offset detected is outside acceptable limits (P7-01).
• DC offset in motor phase currents.
• Faulty current sensor (CT).
• Improper motor phase insulation.

Click steps to track your progress.

1. 1

   Modify the control sequence to prevent restarting operation when induced voltage remains in the motor.

2. 2

   Set b3-01 = 1 [Speed Search at Start Selection = Enabled] or use external Speed Search commands (H1-xx = 61, 62) to safely re-engage with a spinning motor.

3. 3

   If the above steps do not resolve the fault and a drive hardware problem is suspected after initial troubleshooting, replace the drive. Perform a Fault Reset.