Motor phase V missing

What does 31 mean?

One of the motor output phases (Phase V) is detected as missing by the drive. This typically indicates a disconnected motor cable, a broken wire, or a poor connection at either the drive or motor terminals, preventing proper motor operation.

• Open circuit in the motor cable for phase V between the drive's V terminal and the motor's V terminal.
• Loose or corroded connection at the drive's output terminal V or the motor's terminal box for phase V.
• Internal failure of an output IGBT for phase V within the drive.
• Open circuit fault in the motor winding for phase V, resulting in no current path.
• Dislodged or damaged busbar connection for phase V inside the drive's power section.

Click steps to track your progress.

1. 1

   De-energize the drive and verify 0VDC at the drive's U, V, W output terminals.

2. 2

   Measure continuity of the motor cable for phase V from the drive's V terminal to the motor's V terminal.

3. 3

   Inspect connections at drive terminal V and the motor's terminal box for phase V for looseness, corrosion, or damage.

4. 4

   Measure resistance of the motor windings (U-V, V-W, W-U) at the motor's terminal box, verifying they are balanced and within specification (e.g., 0.5-20 Ohms).

5. 5

   If motor and cable are confirmed good, measure resistance between drive output terminal V and the DC bus (+) and (-) terminals to check for IGBT integrity.