YASKAWA P7 User Manual page 154

Digital
Operator Display
UL3
Undertorque Detection 1
Undertorq Det 1
Drive output current < L6-02 for more than
(Flashing)
the time set in L6-03
DC Bus Undervoltage
UV
The DC bus voltage is ≤ L2-05
DC Bus Undervolt
208-240Vac: Trip point is ≤ 190Vdc
(Flashing)
480Vac: Trip point is ≤ 380Vdc
Control Power Supply Undervoltage of the
UV2
control circuit when running
CTL PS Undervolt
Soft Charge Circuit Fault
UV3
The pre-charge contactor opened while the
MC Answerback
Drive was running
Table 6.2 Alarm Displays and Processing
Description
Diagnostic & Troubleshooting 6 - 10
Cause
Motor is underloaded
Low input voltage at R/L1, S/L2
and T/L3
The acceleration time is set too
short
Voltage fluctuation of the input
power is too large
External load connected pulling
down the Drive power supplies
Contacts on the soft charge
contactor are dirty and the soft
charge contactor does not
function mechanically
Corrective Action
Ensure the values in
L6-02 and L6-03 are appropriate
Check application/machine status
to eliminate fault
Check the input circuit and
increase the input power to
within specifications
Extend the time in C1-01
Check the input voltage
Cycle power off and on to the
Drive
Repair or replace the Power PCB/
Gate Drive PCB
Cycle power off and on to the
Drive
Check the condition of the soft
charge contactor