dc millivolts ranges, by setting the switch to the
with the direct-drive calibrating potentiometer
"9V" and "900MV" positions (par. 14)
s w i t c h (par. 29) and the tachometer indicator
calibrating potentiometer (par. 67) to calibrate
t h e tachometer indicator meter (par. 13) for
(Designated as READ)
either a direct-driven or pully-driven generator
The dc volts-millivolts momentary-on switch
or alternator. When testing direct-driven gen-
(21), located directly under the dc volts-milli-
e r a t o r s or alternators the switch is set in the
volts meter (4) in the center of the main control
" L O " position and the generator speed (rpm)
panel, is a 25-ampere, 30 volt dc, single-pole,
is read on either the 0-12 or 0-5.5 scale of the
single-throw, off momentary-on toggle switch,
t a c h o m e t e r indicator meter which is deter-
used to connect the dc volts-millivolts meter (4)
mined by the driving head (4 or 5, fig. 7) on
in the circuit with the dc volts-millivolts range
w h i c h the generator or alternator is mounted.
s e l e c t o r switch (par. 30). Holding the switch
For a pulley-driven generator or alternator the
lever up to the "READ" position when perform-
p o s i t i o n of this switch is determined by the
i n g tests will activate the dc volts-millivolts
d r i v e n generator or alternator speed and the
m e t e r (par. 14).
p r e s e t speed (par. 84c(4)). The scale 0-12
o r 0-5.5 of the tachometer indicator meter
which is used is determined as stated above.
(Designated as DC VOLTMETER RANGE
SELECTOR)
Dc voltmeter range selector switch (22), lo-
brating Potentiometer Switch (Desig-
cated directly under the dc voltmeter (5) near
nated as TACHOMETER INDICATOR
the right hand center of the main control panel,
DIRECT DRIVE-CAL POT)
is a 5-position (position between marked volt-
T h e tachometer indicator direct-drive-cali-
age positions open circuit), 1-pole, 1-deck, ro-
b r a t i n g potentiometer switch (19), located di-
t a r y type selector switch. It is used to place
rectly under the tachometer meter (3) near the
the dc voltmeter (5) in the circuit of the dc sys-
left hand center of the main control panel, is
tem undergoing test, within ranges of 10, 20,
a 3-position (center position open circuit),
and 50 dc volts, by setting the switch in the
1-pole, 1-deck, rotary type selector switch. It is
10V (X1), 20V (X2), and 50V (X5) positions
used in conjunction with the tachometer indi-
(par. 15).
c a t o r high-low switch (par. 28), and the ta-
c h o m e t e r indicator calibrating potentiometer
(par. 67) to calibrate the tachometer indicator
a. General. The dc voltmeter circuit selector
m e t e r (par. 13), for either a direct-driven or
switch (23), located directly under the dc volt-
p u l l e y - d r i v e n generator or alternator. When
m e t e r (5) near the right hand center of the
t e s t i n g direct-driven generators or alternators
m a i n control panel, is a 7-position (position
the switch is set in the "DIRECT-DRIVE" po-
between marked positions open circuit), 2-pole,
sition and for pulley-driven generators and al-
2-deck, rotary type selector switch. It is used
ternators it is set in the "CAL POT" position.
to place the dc voltmeter (par. 15) in parallel
with the battery circuitry of the test stand or
to place the dc voltmeter in the testing circuitry
(Designated as DC VOLTS/MILLIVOLTS
of the test stand for a variety of tests on a dc
RANGE SELECTOR)
systems and ac/dc systems. It is also used to
The dc volts-millivolts range selector switch
place the dc voltmeter in the circuit of a voltage
(20), located directly under the dc volts-milli-
source external to the test stand. These various
volts meter (4) in the center of the main control
procedures are acquired by placing the switch
panel, is a 3-position (center position open cir-
i n positions: " B A T VOLTS," "VARIABLE
VOLTS, " "RECT GEN," and "EXT VOLTS,"
cuit), 2-pole, 1-deck, rotary type selector
b through e below.
switch. It is used to place the dc volts-milli-
volts meter (4) in the circuit of the dc system
b. "BAT VOLTS" Position. T h e " B A T
undergoing test, in either the 9 dc volts or 900
VOLT" position connects the dc voltmeter cir-
22
