Troubleshooting 10-27
1560D-UM051D-EN-P – February 2005
If the resistance checks from the Thyristor testing section were abnormal
and the thyristors checked out OK, there may be a problem in the snubber
or resistor circuits.
1. Remove all power from the equipment.
To avoid shock hazard, ensure main power has been
disconnected before working on the controller, motor or
control devices. Verify that all circuits are voltage free
using a hot stick or appropriate voltage measuring device.
Failure to do so may result in burns, injury or death.
2. a) For units rated over 2000 volts:
Disconnect wires IL1, IT1, IL2, IT2, IL3, IT3 from the Voltage
Feedback board. On the 1562D, 360A, 2400V to 4160V, the voltage
feedback board is located on the back of the low voltage panel or
on the left side of the structure. Consult OEM documentation for
the location of the feedback board on the 1503D. Measure the
resistance from the end of each of these wires to the following
points on the gate-driver boards:
IL1 to Phase A cathode, top position
IT1 to Phase A cathode, bottom position
IL2 to Phase B cathode, top position
IT2 to Phase B cathode, bottom position
IL3 to Phase C cathode, top position
IT3 to Phase C cathode, bottom position
b) For units rated 1500 volts or less:
Disconnect wires 2L1, 2T1, 2L2, 2T2, 2L3, 2T3 from the Voltage
Feedback board. Measure resistors R7 to R12 and verify the
readings per the chart below.
The measured resistance based on the rated voltage of the MV
Dialog Plus™ should be per the chart below:
Rated Voltage (V) Resstance (k Ohm) ± 2%
1000 20
1300 30
1500 50
2400 75
3300 100
4160 150
5500 195
6900 224
Snubber and Resistor Circuit
Testing
A T T E N T I O NA T T E N T I O N
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