Speed Feedback Loss

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.

• Encoder or resolver cable disconnected, damaged, or experiencing insulation breakdown.
• Faulty encoder/resolver unit (e.g., internal component failure, dirty optics).
• Incorrect wiring of encoder/resolver signals to the drive's feedback input terminals (e.g., A, A', B, B', Z, Z').
• Improper encoder/resolver parameter settings (e.g., number of pulses, type, P1-15, P1-16).

Click steps to track your progress.

1. 1

   1. Verify the encoder/resolver cable is securely connected to the drive's feedback terminals and the motor-mounted sensor.

2. 2

   2. Measure the supply voltage at the encoder/resolver (e.g., 5VDC or 12VDC) directly at its terminals.

3. 3

   3. Using an oscilloscope, verify the encoder/resolver A/B/Z phase signals at the drive's input terminals while the motor rotates slowly.

4. 4

   4. Check drive parameters related to speed feedback (e.g., P1-15 for encoder resolution, P1-16 for feedback type) for correct values.

5. 5

   5. Ensure the encoder/resolver cable shielding is properly terminated at the drive's PE terminal and at the motor end.