Manual

Component Definition and Maintenance 5-21
7000 “A” Frame 7000A-RM001A-EN-P – January 2011
The Symmetrical Gate Commutated Thyristor (SGCT or device) with
attached circuit board is located within the PowerCage assembly.
SGCTs must be replaced in matched sets:
• 3300V and 4160V systems use sets of 2
• 6600V systems use sets of 3
The SGCT and associated control board are a single component. There
will never be a time when the device or the circuit board will be changed
individually. There are 4 LEDs on the SGCT, and the following table
describes their functions:
LED 4 Green
Solid Green indicates that the Power Supply to the Card is
OK
LED 3 Green
Solid Green indicates that the Gate-Cathode resistance is
OK
LED 2 Yellow
LED ON indicates the gate is ON, and Flashes alternately
with LED 1 while gating
LED 1 Red
LED ON indicates the gate is OFF, and Flashes alternately
with LED 2 while gating
Do not adjust outside nut.
SGCT captive screws
Inside nut used for loosening
and applying load to assembly
Figure 5.18 – Replacing the SGCT
Symmetrical Gate
Commutated Thyristor
Replacement