TM 11-6625-3041-30/TO 33A1-8-908-12
1-22. AC INPUT (A2) NUCLEAR SHUTDOWN
Nuclear
Shutdown
by the power supply to overconduct and burn up. Therefore, a
Nuclear Shutdown circuit is used to turn off the power supply
in the event of nuclear radiation.
Q18 is normally on. Nuclear radiation turns off Q18, which
turns Q19 on and sets the base of Q20 high. Q20 turns on,
which sets the base of Q21 high. Q21 turns on, which sets
the base of Q22 low. Q22 conducts, which sets its collector
high.
12V
The high level at Q22 collector turns on the +12V Crowbar Q1
and the -12V Crowbar Q2. Q1 shorts out the +12V(J)A supply
Crowbars
(+12V Ref Supply on the A2 AC Input card) and the +12V(B)A
supply (+12V dc output from the A1 Multi VDC card). Q2 shorts
out the -12V supply (-12V dc output from the A1 Multi VDC card).
The high level at Q22 collector is also applied through J1
pin 7 to the input of the Switcher Crowbar on the Multi VDC
card. The Switcher Crowbar turns on and shuts down the
Switcher, which shuts down the dc supplies.