No motor

What does 3 mean?

No motor is connected to the output of the frequency converter. This indicates an open circuit condition on the motor output terminals.

• Motor cable severed or disconnected from the drive output terminals (U, V, W) or the motor terminal box.
• Internal open circuit in one or more motor windings (e.g., due to thermal overload, insulation breakdown).
• Loose or corroded electrical connections on the motor terminal block or the drive's output terminals.
• External motor protection device (e.g., thermal overload relay, contactor) tripped or faulty, interrupting power.
• Incorrect motor cable sizing or severe cable damage causing high resistance or an open circuit.

Click steps to track your progress.

1. 1

   Safely de-energize the drive and motor. Verify all physical connections from the drive output (U, V, W) to the motor terminal box.

2. 2

   Measure the resistance between each pair of motor output terminals at the drive (U-V, V-W, W-U); all should be equal and low impedance (e.g., <1 Ohm).

3. 3

   Measure the insulation resistance of the motor windings to ground using a megohmmeter (e.g., 500VDC test, expected >1MOhm).

4. 4

   Disconnect the motor cables from the motor terminal box and measure the resistance of each motor winding (U-V, V-W, W-U) directly at the motor.

5. 5

   Inspect any motor contactor or starter (if present) for proper operation, ensuring all main contacts close when commanded.