Snubber capacitance (sgct device) – Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - ForGe Control (PanelView 550) User Manual
Page 271
Rockwell Automation Publication 7000-UM151E-EN-P - January 2013
271
Snubber Testing Appendix C
Refer to
Table 14 on page 269
to determine the appropriate snubber resistance
value for the current rating of the SGCT used.
If the resistor is found to be out of tolerance, refer to
for detailed instructions on replacing the snubber
resistor assembly.
Snubber Capacitance (SGCT Device)
Turn the multimeter from the resistance to capacitance measurement mode.
Proceed to verify the snubber capacitor by measuring from the test point to the
heatsink adjacent to the right.
Figure 255 - Subber capacitor test
Refer to
Table 14 on page 269
to determine the appropriate snubber capacitance
value for the current rating of the SGCT used.
The capacitance measured is actually affected by the snubber capacitor and other
capacitance in the circuit, including capacitance from the gate driver circuit. You
are actually looking for a consistent reading for all devices.
If the capacitor is out of tolerance, refer to
for detailed instructions on how to replace the snubber
capacitor.
Heatsink
Heatsink
Snubber
Resistor
Snubber
Capacitor
Sharing Resistor
SGCT
Test Point
Measure capacitance
between heat sink
and test point (or
from heat sink to
heat sink)
Snubber test point