TM 55-4920-221-14
OFF pushbutton of load disconnect switch (21) and
(a) Connect POSITIVE generator lead
rotate dc generator load switches (45) in the OFF
to B+28V terminal of dc generator input terminals (35,
position.
(15) Stop generator under test, disconnect
(b) Connect NEGATIVE generator lead
leads, and position switches in OFF position.
to 500A 28V, 250A 28V, or 50A 28V terminal of dc
generator input terminals (35) as determined by voltage
b. Dc Voltage Regulator Test.
rating of generator under test.
(1) Install voltage regulator to be tested on
(c) Connect A & D field generator leads
voltage regulator pad (15).
to A and D field terminals (53).
(2) Perform operations as described in
(3) Rotating dc voltmeter circuit selector (16)
paragraphs a(1) through (5) above.
in GEN V position indicates output voltage reading on
(3) Position rheostat test switch (25) in TEST
dc voltmeter (13).
GENERATOR position, and rheostat regulator switch
(4) Rotating rheostat regulator switch (26) in
(26) in REGULATOR position, placing regulator in
RHEOSTAT position, and rheostat test switch (25) in
control of generator voltage.
TEST GEN position, places field rheostat (44) in control
(4) Bring generator to operating speed and
of output voltage.
note regulator operating voltage.
(5) Rotate dc ammeter terminal selector (43)
NOTE
in appropriate scale as determined by negative lead
Allow regulator approximately 15
connection in b above.
minutes to warm up before applying
(6) Operate generator under test at its rated
any load to generator.
rpm and rotate field rheostat (44) until desired output
(5) Load generator and observe meter
voltage is obtained.
readings as described in paragraphs a(7) and (8) above.
(7) Depress LOAD ON pushbutton of load
(6) Use load disconnect switch (21) for load
disconnect switch (21).
Close dc generator load
interruption and shock test.
switches (45) increasing load on generator in increments
(7) Read equalizer-coil voltage of regulator
until rated load is reached.
by connecting external leads from K and D terminals on
NOTE
voltage regulator pad to external voltmeter terminals
By proper use of load switches and
(19).
T3 variable control (46), it is possible
(8) Rotate dc voltmeter circuit selector (16)
to obtain variation from 0 to 500
on EXTERNAL VOLTS position and read voltage on dc
amperes.
voltmeter (13).
NOTE
(9) Read pile voltage by placing dc voltmeter
With application of load, generator
circuit selector (16) in PILE V position.
voltage will drop off and it will be
(10) Press equalizer coil test switch (22) and
necessary to continuously adjust the
ensure generator voltage drops approximately 2 volts.
field rheostate.
Be certain to
(11) Insert headset jack into phone jack (24)
increase
the
generator
output
while maintaining generator load.
voltage prior to decreasing load.
(12) Remove load by operating ON-OFF
(8) Read load current on dc ammeter (11)
pushbuttons of load disconnect switch (21) and listen for
and field current on dc ammeter (12).
instability of regulator as indicated by clicking noises of
(9) Measure field voltage, determined by
carbon pile.
generator under test, by connecting external leads to
(13) Adjust carbon pile for minimum noise.
external voltmeter terminals (19), and + lead to A+ and -
(14) Upon completion of test, perform
35 lead to D or E.
operations described in paragraph a(14) and (15) above.
(10) Rotate dc voltmeter circuit selector (16)
c. Reverse-Current Cutout Test. Reverse-current
on EXTERNAL VOLTS position and read voltage on the
cutout test can be performed by using either an external
dc voltmeter (13).
battery or an external generator.
(11) Use load disconnect switch (21) for load
(1) External battery.
interruption and shock test.
(a) Mount cutout relay to be tested on
(12) Rotate dc voltmeter circuit selector (16)
relay pad (27, figure 6).
on EQUALIZER V position, and observe equalizer
NOTE
voltage on dc voltmeter (13).
When connecting relay, remove
(13) Perform any other tests required by
connection link between BAT + and
manufacturer's specifications.
Gen. + terminals.
(14) Upon completion of tests, decrease
generator voltage with field rheostat (44). Depress the
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