Altivar drive shows negative frequency but motor runs forward

This typically indicates incorrect motor phase rotation. The drive must run in reverse, indicated by the negative frequency, for the motor to rotate in the intended direction.

To correct the motor rotation:

1. Stop the drive and follow the appropriate electrical safety procedures.
2. Swap any two motor leads.
3. Restart the drive and issue a Forward Run command.
4. Verify that the motor rotates in the correct direction and the displayed frequency is positive.

For systems with a bypass:
Verify the motor rotation in both drive and bypass modes.

• Correct in bypass, incorrect in drive mode: Swap any two motor leads at the drive output (T terminals).
• Correct in drive mode, incorrect in bypass: Swap two phases at the incoming power connection or at the input of the bypass contactor.
• Incorrect in both drive and bypass modes: Swap any two phases at the motor connection.

Output Phase Rotation parameter:
Some Altivar drives allow the output phase rotation to be changed through a parameter. On ATV600, ATV900, and ATV340 drives, this is the PHR (Output Phase Rotation) parameter.

PHR can be useful for testing. However, physically correcting the wiring is recommended for a permanent solution because the parameter setting may be lost if the drive is reset to factory defaults.