A30031 — Power unit: Hardware current limiting in phase U

A30031 reports that the hardware current limiting of the power unit has responded in phase U. The response is brief by design: pulsing in that phase is inhibited for one pulse period, and the drive takes no further action on its own. The manuals add a note that helps read the message correctly: the hardware current limiting is monitored separately for each output phase, and this alarm is always output when the limiting responds in phase U of a Power Module — the other phases have alarms of their own.

• The closed-loop control parameters do not match the motor as parameterized and connected.
• The motor or its power cables are faulty.
• The power cables exceed the maximum permissible length.
• The load on the motor is too high.
• The power unit is defective.

1. Check the motor data against the motor actually connected; if they do not match, recalculate the control parameters (p0340 = 3). Running a motor data identification (p1910 = 1, p1960 = 1) is the alternative the manual offers.
2. Check the motor circuit configuration (star/delta).
3. Check the motor load.
4. Check the power cable connections.
5. Examine the power cables for a short-circuit or ground fault.
6. Check that the length of the power cables stays within the maximum permissible length.

• p0340 — set to 3 to have the control parameters recalculated automatically from the motor data when they do not fit the connected motor.
• p1910 — set to 1 to run a motor data identification, the manual's alternative to recalculating with p0340.
• p1960 — selects the moving measurement performed during that identification and is set to 1 together with p1910.

No acknowledgement is needed: the alarm clears itself as soon as the hardware current limiting no longer responds in the phase. If it keeps returning, work through the checks above — a repeated response points to the motor data and parameters, the motor and its power cables, the load, or a defective power unit.