Wire break in phase A

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A wire break (loss of continuity) has been detected or reported in phase A of the motor connection, either within the drive or at the terminal. This critical fault means one of the motor phases is open-circuited. Attempting to operate the motor with a phase break can lead to severe damage to both the motor and the drive due to unbalanced currents.

• Open circuit in the motor power cable for phase A between the drive output terminal (e.g., U) and the motor terminal.
• Loose or corroded connection at the drive output terminal U or the corresponding motor terminal (e.g., T1).
• Internal winding break in phase A of the motor, preventing current flow.
• Faulty motor contactor or relay with an open contact for phase A in the motor power path.
• Drive's internal current sensor for phase A (e.g., R0-04) malfunctioning or reporting zero current despite motor operation.

Klikk på steg for å spore fremgangen.

1. 1

   Power down the drive and motor, then measure the resistance of the motor cable phase A (e.g., from drive terminal U to motor terminal A/T1) using an ohmmeter to confirm continuity.

2. 2

   Disconnect the motor cable from both the drive output (U) and the motor input (A/T1), then visually inspect and retighten all connections.

3. 3

   Measure the resistance of the motor windings (e.g., U-V, V-W, W-U) at the motor terminals; an open circuit on one phase (e.g., U-V infinite, U-W infinite) indicates an internal motor fault.

4. 4

   If a motor contactor is used, check its contacts for continuity across phase A (e.g., terminals 1-2) with the contactor energized and de-energized.

5. 5

   Temporarily swap the motor phase A and B connections at the drive (connect motor Phase A cable to drive V, motor Phase B cable to drive U) and observe if the fault shifts to 'Wire break in phase B'.