Overspeed

What does SOF mean?

The motor speed has exceeded its commanded or permissible limit, often due to an unstable control loop, an excessive regenerative load, or a mechanical runaway condition. This fault is critical as it can lead to mechanical damage to the driven equipment, create safety hazards, and result in a complete loss of control over the motor.

• Unstable PID control loop parameters (e.g., proportional gain P1-10 too high) causing oscillations and speed runaway.
• Loss or corruption of motor speed feedback signal (e.g., from encoder) due to damaged cable, loose connection, or faulty sensor.
• Mechanical decoupling of the motor from the driven load, allowing the motor to free-wheel at high speeds.
• Excessive regenerative load exceeding the drive's braking capability, leading to an uncontrolled increase in DC bus voltage and speed.
• Incorrectly configured maximum speed limit (P1-06) or minimum speed limit (P1-07) allowing the motor to exceed safe operating limits.

Click steps to track your progress.

1. 1

   1. Verify the encoder feedback cable connections at the drive terminals (e.g., A, A/, B, B/, Z, Z/) and the encoder are secure, clean, and properly shielded.

2. 2

   2. Monitor the actual motor speed feedback (e.g., via digital display or Modbus register) and compare it against the commanded speed (P1-01) for discrepancies.

3. 3

   3. Review and adjust PID control loop parameters (e.g., P1-10 Proportional Gain, P1-11 Integral Time) to ensure system stability; reduce gains incrementally.

4. 4

   4. Perform a mechanical inspection of the motor coupling to the driven load to ensure it is secure and not allowing the motor to overspeed independently.

5. 5

   5. Check the maximum speed limit (P1-06) parameter to ensure it is set appropriately for the application and the motor's rated speed.