YASKAWA P7 User Manual page 151

Digital
Operator Display
DC Bus Undervoltage
UV1 The DC bus voltage is ≤ L2-05
DC Bus Undervolt
208-240Vac: Trip point is ≤ 190Vdc
480Vac: Trip point is ≤ 380Vdc
Control Power Supply Undervoltage
UV2
Undervoltage of the control circuit when
CTL PS Undervolt
running
Soft Charge Circuit Fault
UV3
The pre-charge contactor opened while the
MC Answerback
Drive was running
Some features within the PI function group, cause the Drive to shut down momentarily (e.g. Sleep Function,
Snooze Function, Feedback Loss feature etc.) Upon recovery from the conditions that activate these features,
WARNING
the Drive may start unexpectedly. Therefore, when enabling these features take appropriate measures to
notify personnel working with this equipment that unexpected starting may occur.
Table 6.1 Fault Displays and Processing
Description
Diagnostic & Troubleshooting 6 - 7
Cause
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
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
Remove all control wiring and
test Drive
Cycle power off and on to the
Drive
Check the condition of the soft
charge contactor
Repair or replace the Power PCB/
Gate Drive PCB