IndustrialDriveDataDrive Board & Diagnostic Database
Control Techniques / Nidec fault record

Feedback / encoder instability: Encoder Feedback Noise or Instability

Closed-loop Unidrive application is unstable, trips under load, hunts, overspeeds or reports feedback-related symptoms.

Meaning of the indication

The drive may be reacting to poor or noisy feedback rather than a failed output module. The route begins with encoder supply, shield/grounding, cable routing, option module and motor-data evidence.

Checking order

  1. Record encoder type, option module and whether the problem follows machine movement.
  2. Inspect feedback cable shielding, grounding and routing away from motor output cables.
  3. Verify encoder supply and signal integrity where qualified.
  4. Check feedback direction, motor data and closed-loop tuning context.
  5. Preserve any option-module or HF-trip evidence before swapping control hardware.

Suspect areas

EncoderFeedback cableShield/groundOption moduleMotor dataControl tuning
Fault-specific caution

Unstable closed-loop motion can create dangerous machine movement; secure the axis before testing.

Diagnostic workflow

Workflow
Unidrive PS.24V / Thermal / Feedback Evidence Workflow

Unidrive reports PS.24V, thermal feedback symptoms, O.ht/O.ht1 or feedback instability with option modules and external control wiring.

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