Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - Classic Control - Manual (Page 198)

Commissioning 4-39
7000 “B” Frame 7000-UM150I-EN-P – June 2013
Snubber Capacitance (SCR Device)
Turn the multimeter from the resistance to capacitance measurement
mode. Proceed to verify the snubber capacitor by measuring from
the test point and the white wire at the 2-pole device snubber plug
(labeled snubber).
Resistance between Test Point and white wire
at 2-pole plug is snubber capacitance
Sharing Resistance
Snubber Resistance Snubber Capacitor
Testpoint
To Gate
Driver Board
Heatsink Heatsink
Sharing Resistance
Snubber Resistance Snubber Capacitor
Testpoint
To Gate
Driver Board
Heatsink Heatsink
Figure 4.12 – Snubber Capacitance Test
To test the snubber capacitance, disconnect the plug of the self-
powered gate driver board labeled SHARING and SNUBBER. The
resistance between the white wire of the plug and the Test Point to its
left is the snubber capacitance.
Refer to Table 4.B to determine the appropriate snubber capacitance
value for the current rating of the SCR used. You should read the
actual snubber capacitor value shown in the table.
If the capacitor is found to be out of tolerance, refer to Chapter 6 –
Component Definition and Maintenance for detailed instructions on
how to replace the snubber capacitor.