Speed Deviation Excess Detection

What does E.OSD mean?

The inverter output is shut off because the motor speed significantly deviated from the command value during Vector or PM sensorless vector control, preventing proper control. This usually occurs when Pr.285 Speed deviation excess detection frequency is active and can be caused by sudden load changes or incorrect parameter settings. Prolonged deviation can lead to unstable operation.

• Mechanical overload or jam causing the motor to stall or significantly slow down below the commanded speed.
• Incorrect motor parameters (e.g., Pr.80 Motor rated current, Pr.83 Motor poles) entered into the inverter, leading to inaccurate vector control.
• Faulty encoder feedback (e.g., disconnected phases, noisy signal, incorrect PPR setting Pr.33) leading to an erroneous speed measurement.
• Insufficient motor torque output due to low voltage or current limits (e.g., Pr.14 Motor rated torque, Pr.15 Torque boost) preventing acceleration to command.
• Inverter output phase loss (e.g., due to contactor failure, loose terminal) or motor winding damage, leading to unbalanced torque.

Click steps to track your progress.

1. 1

   1. Verify mechanical load conditions; disconnect the motor and check for binding, excessive friction, or jams in the driven equipment.

2. 2

   2. Perform a motor auto-tuning procedure (e.g., Pr.76 set to 1 for offline tuning) to accurately identify motor electrical parameters.

3. 3

   3. Inspect encoder wiring for loose connections or damage, and verify encoder pulses are accurately registered by the inverter.

4. 4

   4. Check inverter output terminals U, V, W for proper voltage balance (expected: symmetrical 3-phase output) during operation.

5. 5

   5. Adjust Pr.371 (Speed deviation detection level) to a higher value if the application allows for greater speed tolerance.