Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - ForGe Control (PanelView 550) - Manual (Page 272)

272 Rockwell Automation Publication 7000-UM151E-EN-P - January 2013
Appendix C Snubber Testing
SCR Testing
The following procedure verifies SCR semiconductors and all associated snubber
components. For quick reference to the expected resistance and capacitance
values, refer to
Table 15 below. A simple schematic diagram in Figure 256 shows
the snubber component connections across an SGCT.
Table 15 - SCR Snubber Circuit Resistance and Capacitance Values
Figure 256 - SCR snubber circuit connections
If you find a damaged device or snubber component, follow the detailed
replacement procedure located in
Component Definition and Maintenance on
page 23 .
SCR Rating Sharing Resistance Snubber Resistance Snubber
Capacitance
350, 400, 815 Amp 80kΩ 60Ω 0.5 µf
SCR Resistance Measurement Measured Resistance
Inverter Rectifier (AFE only)
SCR Anode-Cathode Resistance
(Heatsink to Heatsink) k-Ω
(Lowest) (Highest) (Lowest) (Highest)
SCR Gate-Cathode Resistance (across
SCR Phoenix Connector)Ω
Heatsink Heatsink
To Gate Driver Board
Heatsink Heatsink
Snubber
Resistor
Snubber
Capacitor
Sharing Resistor
Test Point