Maximum system speed exceeded

What does NMAX mean?

The maximum system speed, set by C0596, has been exceeded. This can be caused by an active load that is too high, the drive not being speed-controlled, or an excessively limited torque, leading to overspeed conditions.

• Incorrectly set maximum speed limit (C0596) that is lower than the actual required or commanded speed.
• Uncontrolled acceleration due to insufficient braking torque, especially with regenerative loads (e.g., lowering a heavy hoist).
• Drive operating in torque control mode without a speed governor, allowing the motor to overspeed with a light load.
• Mechanical decoupling of the load from the motor, causing the motor to spin freely at high speeds.
• Faulty speed feedback (encoder/resolver) providing incorrect, low speed values, leading the controller to command excessive output frequency.

Click steps to track your progress.

1. 1

   Review and adjust parameter C0596 (Maximum system speed) to a value appropriate for the application and motor's maximum safe speed.

2. 2

   Verify the braking resistor connection and value (P1-52, P1-53) and braking chopper functionality for applications with regenerative loads.

3. 3

   Confirm the drive operating mode (e.g., C0015 = 1 for speed control) to ensure it is actively regulating motor speed.

4. 4

   Physically inspect the coupling between the motor and the load for any damage or disengagement.

5. 5

   Verify the speed feedback sensor (encoder/resolver) signal integrity using an oscilloscope while the motor is running.

6. 6

   Check acceleration/deceleration ramps (P1-00, P1-01) to ensure they are not set too short, which can lead to overshooting speed limits.