UL4

Undertorque Detection 2

Yaskawa · J1000 AC Drive

What does UL4 mean?

The motor current has fallen below a secondary minimum value set in L6-05 for longer than the allowable time specified in L6-06. Similar to UL3, this suggests either incorrect parameter tuning for the current load or a fault in the machine's mechanical system that is causing reduced torque.

Source: Yaskawa J1000 AC Drive
View Official PDF