Speed Deviation

What does dEv mean?

This minor fault occurs when the deviation between the speed reference and the actual speed feedback (typically from a PG option card) exceeds the threshold set in F1-10 for a duration longer than F1-11. Common causes include excessive load, improperly set acceleration/deceleration times, mechanical lock-ups, or incorrect parameter scaling. Failure to resolve this can lead to unstable motor operation, mechanical stress, or an inability to maintain desired process speeds.

• Mechanical issues with the load (e.g., excessive friction, binding, slipping belt, sudden load changes) causing the actual motor speed to deviate significantly from the speed reference.
• Poorly tuned speed control parameters (e.g., C1-01 Proportional Gain, C1-02 Integral Gain, C1-03 Derivative Gain) leading to sluggish response or oscillations.
• Noisy or unreliable speed feedback signal from the encoder/PG (e.g., due to poor cable shielding, faulty encoder, or loose connections).
• Insufficient motor torque or undersized motor for the application, preventing it from following the speed reference accurately under load.
• Incorrect settings for speed deviation detection parameters F1-10 (Deviation Level) or F1-11 (Deviation Time), making the detection too sensitive.

Click steps to track your progress.

1. 1

   Verify the settings of Parameter F1-10 (Speed Deviation Detection Level) and F1-11 (Speed Deviation Detection Time) against the expected speed regulation performance of the application.

2. 2

   Monitor the speed reference (e.g., U1-04) and actual speed feedback (e.g., U1-07) simultaneously using the drive's display or HMI to observe the real-time deviation.

3. 3

   Adjust speed control parameters (e.g., C1-01 Proportional Gain, C1-02 Integral Gain) systematically to improve speed regulation and reduce deviation, following the drive's tuning guide.

4. 4

   Inspect the encoder/PG and its cabling for secure connections and proper shielding to ensure a clean and accurate speed feedback signal.

5. 5

   Check the motor and driven load for any mechanical binding, excessive friction, or slipping mechanisms that prevent the motor from accurately following the speed reference.