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4-12
Component Definition and Maintenance
Uniform Clamping Pressure
7000A-UM151E-EN-P - October 2018
SGCT
400 A SGCT
800 A SGCT
1500 A SGCT
Pressure on the SGCTs must be uniform to prevent damage and to ensure
low thermal resistance. Uniform pressure can be achieved by loosening
the heatsink mounting bolts, tightening the clamp and then tightening the
heatsink bolts. See section "Uniform Clamping Pressure" for instructions.
External filtered air will be directed through the slots of the heatsinks to
carry away the generated heat from the SGCTs. The door filter is
necessary to ensure the slots on the heatsinks do not get plugged with dust
particles.
It is very important to maintain proper pressure on the thyristors. Follow
this procedure whenever changing devices, or whenever the clamp is
loosened completely.
1. Apply a thin layer of Electrical Joint Compound (Alcoa EJC No. 2 or
approved equivalent) to the clamp head pressure pad face.
2. Torque the heatsink bolts to 13.5 N-m (10 ft-lb.) and then loosen each
bolt two complete turns.
3. Tighten the clamp to the proper force until the indicating washers can
just be turned by the fingers with some resistance.
4. Torque the heatsink bolts to 13.5 N-m (10 ft-lb.) starting with the
center heatsink and moving outward alternating left to right.
5. Check clamp indicating washer.
Device Diameter
38 mm
47 mm
63 mm
Clamp Force
8.6 kN
13.5 kN
20 kN
7000 "A" Frame
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