Excessive Speed Deviation

What does DEV mean?

This fault occurs when the actual motor speed significantly deviates from the commanded speed, particularly in applications using closed-loop control with a PG (Pulse Generator/encoder). It suggests a problem with the speed feedback device, the motor's ability to follow the command, or a tuning issue in the speed control loop. Unresolved deviation can lead to poor process control or mechanical stress.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Inspect the motor for any mechanical binding, excessive load, or damage that prevents it from reaching commanded speeds.

2. 4

   Review the inverter's speed loop tuning parameters (e.g., ASR gains) and perform an auto-tuning procedure if available.

3. 5

   Ensure the commanded speed reference signal is stable and accurate.