ply control (48), is a 7.5-ampere, ac, 120-volt,
comes on when the battery charge timer (46)
60-cps (cycles per second), single-pole, circuit
is set for a time interval.
breaker which provides an overload protection
55. Battery Charge Timer
in the ac input circuit leading to the variable
The battery charge timer (46), located on the
external volts circuit (par. 38). The reset but-
l o w e r left hand end of the front panel, is a
t o n on the circuit breaker, extending through
115-volt, 60-cycle, automatic reset timer having
the front panel will snap out when there is an
a dial division of 5 minutes and a maximum
o v e r l o a d in the circuit and disconnect the ac
interval range of 5 hours. It is used to select
c u r r e n t supply to the variable external volts
a charge time interval when charging the bat-
c i r c u i t . The circuit breaker can be reset by
teries of the test stand. To operate the timer,
pushing the button inward which will reconnect
the black knurled knob at the lower part of the
the ac input circuit provided the overload con-
dial must first be in the fully counterclockwise
dition is corrected.
position to reset the timer and open the output
59. Polarity Reversing Switch (Designated as
circuit, then to activate the output circuit the
POLARITY REVERSING SWITCH POS GND
k n o b is turned clockwise to the desired time
NEG GND)
i n t e r v a l on the dial of the timer and the red
The polarity reversing switch (50), located
b u t t o n depressed, observing that the battery
on the bottom left hand end of the main control
c h a r g e indicator lamp (45) lights up, which
panel, is a 3-position (ON-NONE ON-ON),
indicates that the battery charger is operating
s i n g l e - p o l e , single-throw, 25-ampere, 30-volt
(par. 54).
dc, toggle switch used to change the polarity
56. Battery Charge Circuit Variable Control
w i t h i n the test stand to negative or positive
(Designated as BATTERY CHARGE CIR-
ground (pars. 87 and 88), whichever is required
CUIT INCREASE)
The battery charge circuit variable control
regulators system undergoing test. The switch
(47), located on the left hand end of the front
is placed in the "NEG GND" position for a neg-
panel above the battery charge timer (46), is a
a t i v e ground circuit and in the "POS GND"
120-ac volt input, 0-140-ac volt output, single-
position for a positive ground circuit. The cen-
ter position on the switch is open circuit and
used to adjust the 0-32 dc voltage output of the
will disconnect the system undergoing test from
b a t t e r y charger to the rated voltage value of
t h e circuitry of the test stand and should be
the batteries under charge (par. 33b).
placed in this position after tests are completed.
60. Generator Field External-Internal Ground
57. Dc Variable Power Supply Control (Des-
Switch (Designated as GEN FIELD EXT
ignated as DC VARIABLE POWER SUPPLY
GND INT GND)
0-32VDC INCREASE)
The generator field external-internal ground
The dc variable power supply control (48),
switch (51), located near the bottom left hand
located on the upper left hand end of the front
end of the main control panel, is a 3-position
panel, is identical to the variable control (47)
(ON-NONE ON-ON) single-pole, single-throw,
i n paragraph 56, both physically and electri-
2 5 - a m p e r e , 30-volt dc, toggle switch used to
cally. It is used to adjust the 0-32 dc voltage
connect the field of the generator undergoing
o u t p u t of the variable external volts circuit
test to the proper type ground. The switch is
(par. 38) to the required dc voltage when per-
placed in the "EXT GND" position for a gen-
forming tests on generator regulators and gen-
e r a t o r with an external grounded field and
erator control boxes.
placed in the "INT GND" position for a gen-
58. Dc Power Supply Circuit Breaker (Desig-
e r a t o r with an internal grounded field (par.
n a t e d as DC PWR SUPPLY CIRCUIT
99). The center position on the switch is open
BREAKER)
circuit and will disconnect the field of the gen-
The dc power supply circuit breaker (49) lo-
erator undergoing test or the switch from the
cated on the upper left hand end of the front
circuitry of the test stand and should be placed
panel to the right of the dc variable power sup-
in this position after tests are completed.