Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - ForGe Control (PanelView 550) - Manual (Page 275)

Rockwell Automation Publication 7000-UM151E-EN-P - January 2013 275
Snubber Testing Appendix C
SCR Sharing Resistance Test
To test the sharing resistor of an SCR module, disconnect the 2-pole plug of the
self-powered gate driver board labeled SHARING and SNUBBER on the circuit
board. The red wire of the plug is the sharing resistor. Measure the resistance
between the red wire of the plug and the heatsink to the left. A value of 80 k-
ohms indicates a healthy sharing resistor.
Figure 258 - SCR sharing resistance test
Gate-to-Cathode Resistance
One test that can be performed on SCRs that cannot be performed on SGCTs is
a Gate-to-Cathode Resistance Test. Performing a Gate-to- Cathode resistance
measurement will identify damage to an SCR by revealing either an open or
shorted gate to cathode connection. To test an SCR from gate-to-cathode,
disconnect the SCR gate leads from the self powered gate driver board and
measure the gate-to-cathode resistance on the SCR firing card Phoenix
connector.
Resistance between heatsink and
red wire at plug is sharing resistance