Sgct testing – Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) User Manual
Page 185

Commissioning 4-31
7000 “A” Frame
7000A-RM001A-EN-P – January 2011
SGCT
Testing
The following steps outline how to verify SGCT semiconductors and
all associated snubber components. A quick reference to the
expected resistance and capacitance values can be found in the table
below. A simple schematic in Figure 4.3 shows how the snubber
components are connected across a SGCT.
Table 4.A – SGCT Snubber Circuit Resistance and Capacitance Values
SGCT Rating
Sharing Resistor
Snubber Resistor
Snubber Capacitor
1500 Amp
80 kΩ
6 Ω (AFE Rectifier)
0.2 µf
1500 Amp
80 kΩ
7.5 Ω (Inverter)
0.2 µf
800 Amp
80 kΩ
10 Ω
0.1 µf
400 Amp
80 kΩ
15 Ω (AFE Rectifier)
0.1 µf
400 Amp
80 kΩ
17.5 Ω (Inverter)
0.1 µf
2300V drives will not have a sharing resistor on devices.
Figure 4.4 – SGCT Snubber Circuit Connections
Measured Resistance
SGCT Resistance Measurement
Inverter
Rectifier (AFE only)
SGCT Anode-Cathode Resistance
(Heatsink to Heatsink) k-Ω
(Lowest) (Highest) (Lowest) (Highest)
Snubber Resistance
(Test Point – Heatsink above) Ω
(Lowest) (Highest) (Lowest) (Highest)
Snubber Capacitance
(Test Point – Heatsink on Right)
µF
(Lowest) (Highest) (Lowest) (Highest)
If a device or snubber component is found to be damaged, it must be
replaced using the detailed procedures in Component Definition and
Maintenance.