GE Industrial Solutions AF-650 GP MultiPulse Drive Panel - Manual (Page 17)

MULTIPULSE DRIVE PANEL
17 GE Energy ©2012 GE Company All Rights Reserved
6 Troubleshooting
If careful attention to phase rotation is not
made during connection of the panel to the
three-phase power supply and motor, then
there is only a one chance in four that the
motor will rotate correctly in both drive and
bypass modes.
The other three possibilities and the
corresponding corrective actions are as
follows:
* Problem: Motor turns correctly in Bypass
mode and incorrectly in Drive mode
Solution: Swap two of three
power supply leads AND two of
three motor leads
* Problem: Motor turns correctly in Drive
mode and incorrectly in Bypass mode
Solution: Swap two of three
power supply leads
* Problem: Motor turns incorrectly in both
modes
Solution: Swap two of three
motor leads
Note that if the rotation in bypass
mode is opposite to the rotation in
drive mode, it is possible that the
panel’s motor overload will trip if a
full-speed transition between
modes is attempted. This is due to
the large amount of current
required to decelerate the motor
to a stop prior to accelerating it in
the correct direction.
*Problem: Trouble with VFD and External
Rectifier section.
Solution: It is always good to see the
overall circuit as shown in the figure 6.1. If the
supply breaker keeps tripping, chances are
that one or more diodes are shorted.
Begin by isolation the circuit:
1) Lockout the supply breaker and
wait until the DC bus is below
50VDC.
2) Pull CR4 to keep C1 and C2 off.
3) Remove the +DC Bus and –DC Bus
cables from the VFD (mark them
“+” and “-“).
4) (1, 4, 7) is a phase shifting
transformer and needs to be
disconnected from the VFD. See
figures 6.1, 6.2 and 6.3.
5) Test the 6 VFD diodes using a
diode meter. Measure from L1, L2,
L3 to +DC and –DC. Use the
Service Manual DET-712 for
details on testing and replacing
devices.
6) Whether the VFD rectifiers check
good or bad, the external diodes
still need to be tested. With the
breaker still OFF, open the hood to
the external rectifier section. See
figure 6.3.