91

Encoder Loss

Allen-Bradley · PowerFlex 700 AC Drives

What does 91 mean?

Requires a differential encoder. One of the two encoder channel signals (e.g., A or B) is missing. This indicates a problem with the encoder feedback, which is critical for precise motor control, leading to loss of speed or position regulation.

Source: Allen-Bradley PowerFlex 700 AC Drives
Open Manual (Page 85)