Overspeed occurrence

What does E.OS mean?

This fault indicates that the motor speed has exceeded the programmed overspeed detection level in the FR-A800/A800 Plus Series drive. This protective function prevents uncontrolled acceleration or runaway conditions of the motor.

• Motor or load inertia driven by external forces (e.g., regenerative load, gravity) causing speed to exceed the commanded value.
• Overspeed detection level parameter set too low for the application.
• Faulty speed feedback (e.g., encoder reading incorrectly high or inconsistent).
• FR-A800/A800 Plus Series drive losing control of the motor due to incorrect parameters or improper tuning.
• Brake failure or insufficient braking capacity on a vertical or overhauling application.

Click steps to track your progress.

1. 1

   Verify the overspeed detection level parameter is correctly set above the maximum expected operating speed but below the motor's absolute maximum safe speed.

2. 2

   Check for external forces acting on the motor/load that could cause overspeed, such as regenerative loads or gravity, and ensure adequate braking or regeneration capacity.

3. 3

   If an encoder is used for speed feedback, verify its functionality and wiring for accurate speed measurement.

4. 4

   Review other speed control parameters (e.g., PID gains, acceleration/deceleration times) to ensure stable operation and prevent speed overshoot.

5. 5

   In applications with external forces, ensure any mechanical brakes or external braking systems are fully functional and properly sized.