SPF

Speed Feedback Loss

Schneider Electric · Altivar Machine ATV320 Variable Speed Drive

What does SPF mean?

A loss of speed feedback has been detected. This means the drive is no longer receiving valid speed information from its encoder or resolver. This is critical for closed-loop speed control and can lead to unstable motor operation or a controlled shutdown. If left unresolved, accurate speed control is impossible.

Complete Troubleshooting Guide

  1. 1

    Check the wiring connections for the speed feedback device (encoder/resolver) to the drive for integrity.

  2. 2

    Inspect the speed feedback device for physical damage or misalignment on the motor shaft.

  3. 3

    Verify the speed feedback parameters in the drive (e.g., encoder type, pulses per revolution).

  4. 4

    Test the encoder/resolver output signals with an oscilloscope if possible.

  5. 5

    Ensure the encoder power supply from the drive is present and stable.