Motor phase U missing

What does 30 mean?

One of the motor output phases (Phase U) is detected as missing by the drive. This usually points to 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 U between the drive's U terminal and the motor's U terminal.
• Loose or corroded connection at the drive's output terminal U or the motor's terminal box for phase U.
• Internal failure of an output IGBT (Insulated Gate Bipolar Transistor) for phase U within the drive.
• Open circuit fault in the motor winding for phase U, resulting in no current path.
• Dislodged or damaged busbar connection for phase U 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 U from the drive's U terminal to the motor's U terminal.

3. 3

   Inspect connections at drive terminal U and the motor's terminal box for phase U 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 U and the DC bus (+) and (-) terminals to check for IGBT integrity.