GE Industrial Solutions ASTAT-CD Plus Solid-State Starters - Manual (Page 12)

ASTAT-CD Plus Service Instructions
12
SCR assembly instructions
The mounting surface of the heatsink must be flat
and clean (i.e., bare metal) and the SCR module
surface must be clean. Thermal compound must be
coated on all mating surfaces between the SCR
module and the heatsink. Care must be taken to use
the specified torque for mounting the SCR module.
For SCR module (back to back SCRs in a single
package) on ASTAT-CD Plus sizes J, K, L and M.
Step 23. Clean the heatsink surface with a fine abrasive
such as Scotchbrite, remove all particles from
the surface of the heatsink and wipe the SCR
module mounting surface with a mild solvent.
Step 24. Apply a light coat of thermal compound such
as Electrolube 2 GX to both the SCR module
and heatsink surfaces.
Step 25. Place the contact face of the SCR module and
on the mating heatsink surface and move the
SCR module back and forth several times to
distribute the thermal compound evenly over
the contact surfaces.
Step 26. Use the screws provided to attach the SCR
module to the heatsink. Tighten the screws
alternately to the specified torque
requirement for the SCR module.
Torque requirements are as follows for sizes J,
K, L and M: Tighten the screws through the
SCR module to heatsink to 44 in lb.
Step 27. Reassemble bus bars and MOVs to SCR
modules (Figures 13 and 14). Torque to 26 in
lbs for Size J, 44 in lbs for Size K, and 80 in lbs
for Sizes L and M.
Step 28. Reassemble Protection Board, Power Supply
Board, shield or Communications Board (if
removed), Logic Board, cover and terminal
connectors using Steps 18 and 19.
Light
+
+
- -
S2
S1
20
Ω
1W
(SCR)
Cathode
Anode
Gate
(~.15AMP to .20AMP LOAD)
5VDC
Figure STC
SCR Test Circuit
Remove all power from ASTAT-CD Plus
With S1 closed and S2 open, the lamp should be off.
If lamp is on, SCR is shorted.
With S1 closed and S2 closed, the lamp should turn on.
When S2 is opened, lamp should stay on. SCR is good.
SCR must be disconnected from ASTAT-CD Plus control (yellow and blue
leads disconnected from SCR) and no load connected to ASTAT-CD Plus.