Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - ForGe Control (PanelView 550) - Manual (Page 273)

Rockwell Automation Publication 7000-UM151E-EN-P - January 2013 273
Snubber Testing Appendix C
SCR Anode-to-Cathode Resistance
Performing an Anode-to-Cathode resistance test verifies the integrity of the
SCR. Unlike the SGCT, the SCR uses the snubber circuit to power the self-
powered gate driver boards. The resistance measurement taken across each SCR
should be constant; an inconsistent value may indicate a damaged sharing resistor,
self-powered gate driver board or SCR.
Using an ohmmeter, measure the anode-to-cathode resistance across each SCR in
the rectifier bridge, while looking for similar resistance values across each device.
Snubber Resistance (Test point: Heat
sink above) Ω
(Lowest) (Highest) (Lowest) (Highest)
Snubber Capacitance (Test Point –
Heatsink on Right) µF
(Lowest) (Highest) (Lowest) (Highest)
Sharing Resistance (Red wire from
snubber Phoenix connector—Heatsink
on left) k-Ω
(Lowest) (Highest) (Lowest) (Highest)
SCR Resistance Measurement Measured Resistance
Inverter Rectifier (AFE only)