Yaskawa VCD 723 User Manual

Page 72

Troubleshooting/Maintenance

Troubleshooting Flowcharts

9/15/93

Chart 7. Overcurrent (

) Fault Indication

DOES OUTPUT

CURRENT EXCEED

200% OF RATING?

WITH VCD 723 IN STOPPED CON-
DITION, INCREASE ACCELERATION
TIME BY REPROGRAMMING PER PAC
DIAGRAM, IF OC TRIP OCCURS ONLY

DURING ACCELERATION.

OTHERWISE, REDUCE LOAD.

YES

DOES OC TRIP

OCCUR, OR MAIN CIR-

CUIT CONTACTOR

TRIP, WHEN POWER

IS TURNED ON?

MACHINE JAMMED

OR MOTOR

FAILURE?

CLEAR JAM, OR
REPLACE MOTOR.

DISCONNECT WIRING

FROM OUTPUT TERMINALS

T1, T2 AND T3 AND

CHECK LOAD IMPEDANCE.

CHECK POWER

TRANSISTORS

(SEE TABLE 10).

ARE TRANSISTORS

DAMAGED?

REPLACE
DAMAGED POWER
TRANSISTORS.

WITH VCD 723 IN STOPPED
CONDITION, INCREASE
ACCELERATION TIME BY
REPROGRAMMING PER PAC
DIAGRAM.

DOES OC TRIP
STILL OCCUR?

DECREASE
LOAD INERTIA.

MOTOR STARTED BY CONTACTS

WIRED BETWEEN VCD 723

AND MOTOR?

- REWIRE TO ELIMINATE MOTOR

FULL VOLTAGE STARTING.

- REPLACE DRIVE WITH

ONE OF LARGER CAPACITY.

ERRONEOUS OPERATION

DUE TO NOISE?

REMOVE NOISE SOURCE:

• CONNECT SURGE SUPPRESSOR
TO RELAY AND MAGNETIC CON-
TACTOR COILS.

• PROVIDE LINE FILTER TO
REMOVE NOISE ON INPUT
POWER LINE.

CONTROL PCB OR BASE
DRIVE PCB IS FAULTY.
REPLACE FAULTY BOARD.