GE Industrial Solutions ASTAT-CD Plus Solid-State Starters - Manual (Page 23)

ASTAT-CD Plus Service Instructions
23
backward and forward by hand applying firm
pressure to the SCR. Remove the SCR from
the heatsink, the mating surfaces must be
uniformly coated with thermal compound. If
the mating surfaces are not coated evenly,
apply slightly more thermal compound to the
surfaces and twist back and forth as before.
Step 31. With the 2 SCRs located properly on the
heatsink, i.e. the gate and cathode terminals
on the SCR must be on the proper side of the
heatsink assembly (as disassembled), place
the other heatsink over the SCRs. Refer to
Figure 13.
The clamp is assembled so that the cross
piece(5) with the pressure plate(4) and the
tension bolts (10) are at the top. Underneath
the cross piece (3) with the pressure plate (4)
is put in position and the two tension bolts
(10) are alternately tightened carefully until a
slight resistance is felt. Check that both cross
pieces (3) and (5) are parallel. For this check,
it is sufficient to check that the tension bolts
project equal distances beyond the cross
piece(3). The tension bolts (10) may now be
alternately tightened 1/4 turn at time until
the metal gauge (8) can be easily moved.
NOTE: The tension bolts should not be
tightened beyond the point that the metal
gauge (8) can be easily moved. Never adjust
the preset nut (6).
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.