Drive: No motor detected

What does A07929 mean?

After the inverter pulses are enabled, the absolute current value remains critically small, indicating that no motor is connected or properly detected by the drive. For vector control with an induction motor, this alarm is typically followed by fault F07902. This issue prevents motor operation and can be due to wiring problems or incorrect low-current settings.

• Motor not connected to the drive's output terminals (U, V, W) or motor leads are disconnected.
• Open circuit in one or more motor phases or motor cable due to wire breakage or faulty connection.
• Incorrect motor parameters (e.g., P0304 (Motor rated current) set to 0) preventing proper current measurement and detection.
• Drive output current measurement circuit malfunction, reporting critically low current even if the motor is connected.
• For vector control, the auto-identification (P0340) process failed or was not performed, leading to an inability to detect the motor.

Click steps to track your progress.

1. 1

   1. Verify motor cable connections at both the drive's output terminals (U, V, W) and the motor terminal box.

2. 2

   2. Measure the resistance between each motor phase (U-V, V-W, W-U) at the motor terminals; values should be similar (e.g., 0.5-5 Ohm) for a healthy motor.

3. 3

   3. Check that motor parameters (e.g., P0304 (Motor rated current), P0305 (Motor rated voltage), P0307 (Motor rated power)) are correctly entered.

4. 4

   4. Perform a motor identification run (P0340 = 1) if the drive is in vector control mode and the motor is uncoupled from the load.

5. 5

   5. With power off, visually inspect the drive's output terminals for damage or discoloration that might indicate a faulty power module.