Overspeed

What does OS mean?

This fault is triggered when the motor's actual speed exceeds a pre-set overspeed detection level (F1-08) for a specified time (F1-09). This can occur due to an incorrectly set speed reference, loss of load, a faulty speed feedback device, or the motor being driven externally by the load. Sustained overspeed can cause mechanical damage to the motor and coupled equipment.

• Actual motor speed exceeding the Overspeed Detection Level (F1-08) for longer than the Overspeed Detection Time (F1-09).
• Incorrectly scaled analog speed reference input (e.g., 0-10V signal), leading to an commanded speed higher than intended.
• Loss of mechanical load on the motor (e.g., belt breakage), causing the motor to accelerate beyond the speed command.
• Encoder feedback fault (e.g., disconnected cable, damaged encoder) providing erroneous speed signals to the inverter.
• Overspeed Detection Level (F1-08) or Overspeed Detection Time (F1-09) parameters set too restrictively for the application.

Click steps to track your progress.

1. 1

   1. Verify the Overspeed Detection Level (F1-08) and Overspeed Detection Time (F1-09) are correctly set for the maximum expected motor speed.

2. 2

   2. Measure actual motor RPM using a handheld tachometer and compare it to the commanded speed reference and inverter display.

3. 3

   3. Check the integrity of encoder feedback signals (e.g., A, B, and Z channels) at the inverter's input terminals using an oscilloscope.

4. 4

   4. Inspect the mechanical connection between the motor and load for any disengagement or failure that could lead to motor runaway.

5. 5

   5. Recalibrate the analog speed reference input (e.g., Parameters P4-01, P4-02) to ensure accurate scaling and prevent over-commanding.