Yaskawa VCD 723 - Manual (Page 74)

4 Troubleshooting/Maintenance
68 Troubleshooting Flowcharts
9/15/93
Chart 9. Underload ( uU ) Fault Indication
IS INPUT AC
SUPPLY
CORRECT?
NO
NO
YES
YES
NO
YES
IS THERE
AT LEAST 450VDC
(FOR 460V VCD 723) OR
225VDC (FOR 230V VCD 723)
ON THE DC BUS?
- INCREASE VOLTAGE
WITHIN PROPER RANGE.
- CHECK WIRING BETWEEN
MAIN AC CONTACTOR
AND DRIVE.
DRIVE
IS FAULTY.
REMOVE NOISE SOURCE:
• CONNECT SURGE
SUPPRESSOR TO RELAY
AND MAGNETIC CON-
TACTOR COILS.
• PROVIDE LINE FILTER
TO REMOVE NOISE ON
INPUT POWER LINE.
ERRONEOUS OPERATION
DUE TO NOISE?
CONTROL PCB OR BASE
DRIVE PCB IS FAULTY.
REPLACE FAULTY BOARD.