Scr gate-to-cathode resistance – Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) Commissioning - ForGe Control User Manual
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Rockwell Automation Publication 7000-IN012B-EN-P - June 2014
Chapter 4 Commissioning the Drive
SCR 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.
Figure 41 - SCR gate-to-cathode test
The resistance value from gate-to-cathode should be between 10...20 Ω. A value
close to 0 Ω indicates that there is an internal short in the SCR. An extremely
high value indicates that the gate connection in the device has broken.
If a Gate-to-Cathode test reveals a damaged SCR, refer to publication
for the SCR replacement procedure.
Test points for Gate-to-Cathode
Disconnect SCR
Phoenix
connector from
board