TM 11-5820-765-34
SEQUENCE:
Voltage rises above prescribed value.
Signal applied to gate of SCR2 (Q2).
SCR2
(Q2)
conducts.
Shorts
output.
Opens
circuit
breaker
CB1.
CONTROL CIRCUIT
VOLTAGE
DIVIDER:
Resistors
R121,
R122,
R123
(R21,
R22,
R23).
Connected
across
dc
output
terminals.
REGULATOR DIODE CIRCUIT:
Regulator
CR106
(CR6).
Resistor
R124
(R24).
Transistor
Q104
(Q4).
Supplies gate of silicon controlled rectifier SCR2 (Q2) through limiting resistor R125 (R25).
TRANSISTOR Q104 (Q4):
Compares portion of output voltage with voltage of CR106 (CR6).
NOTE
Portion of voltage compared depends on setting of variable resistor R123
(R23).
IF: Output voltage rises above preset value.
THEN: Q104 (Q4) conducts.
WHICH: Fires SCR2 (Q2).
WHICH: Opens circuit breaker
CB1.
CAPACITOR C108 (C8):
Stabilizes
operation.
I n s u r e s against short time transients firing SCR2 (Q2).
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