Occasionally, a fault can occur where the motor will continue to run, but not in the correct manner. The symptoms and causes may vary considerably. Many of

the possible problems are listed below by symptom along with recommended procedures for determining their causes.

Wrong speed/unit will not respond to command

Possible incorrect reference (speed command).

Ensure that the unit is programmed correctly according to the reference signal being used, and that all reference limits are set correctly as well.

Motor speed unstable

Possible incorrect parameter settings, faulty current feedback circuit, loss of motor (output) phase.

Check the settings of all motor parameters, including all motor compensation settings (Slip Compensation, Load Compensation, etc.) For Closed Loop operation,

check PID settings.

Motor runs rough

Possible over-magnetization (incorrect motor settings), or an IGBT misfiring. Note: Motor may also stall when loaded or the frequency converter may trip occa-

sionally on Alarm 13.

Check setting of all motor parameters.

Motor draws high current but cannot start

Possible open winding in motor or open phase in connection to motor.

Run an auto tune to check the motor for open windings and unbalanced resistance. Inspect all motor wiring connections.

Motor will not brake

Possible fault in the brake circuit. Possible incorrect setting in the brake parameters. The decel time too short. Note: May be accompanied by an alarm or warning

message.

Check all brake parameters and decel time (parameters B-0#).

High Power Service Manual for Unit Sizes 6x

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