20. Tachometer Indicator Meter Calibrating
register 0-25 and 0-50 ac volts through the set-
Binding Posts
tings of a selector switch (par. 36). The meter
is used to measure the ac voltage output of
The tachometer indicator meter calibrating
ac/dc systems and alSO to determine balance
binding posts (10), located directly under the
phase conditions of ac/dc systems through the
t a c h o m e t e r indicator meter (3), near the left
settings of a selector switch (par. 37).
hand center of the meter panel, are a threaded
18. Load Dc
Ammeter Calibrating Binding
Posts
i n d i c a t o r meter. With the high-low switch
T h e load dc ammeter calibrating binding
(18) set between the "Hi" and "Lo" positions,
p o s t s (8), located directly under the load dc
a n d the direct drive-calibrating potentiometer
ammeter (1) on the left hand end of the meter
switch (19) set between the "DIRECT DRIVE"
panel, are a threaded two-piece post which can
a n d "CAL POT" positions, the meter can be
be threaded apart to receive a test lead terminal
calibrated. The movement of the meter pointer
a n d tightened to hold the terminal secure or,
over the entire meter scale is activated by a 0
a plug-in type terminal can be inserted in the
to 12 ac voltage, therefore, by connecting a 0 to
top of the post. They are used when calibrating
12 ac volt supply to the calibrating binding posts
the load dc ammeter. With the selector switch
the meter can be calibrated by varying the ac
(15) set between "50A (X1)" and "150A (X3)"
v o l t a g e and checking the reading at different
positions or between "150 (X10)" positions, and
points on the scale of the meter. To determine
t h e selector switch (16) set between "FREE
whether the speed of either output shaft of the
RUN (X4)" and "STALL TORQUE (X20)"
v a r i d r i v e assembly coincides with the meter
positions, the meter can be calibrated by con-
reading, the speed of the output shafts can be
necting a 50 millivolt dc input to the calibrating
b i n d i n g posts (8) with allowance being made
R e c a l i b r a t i o n instructions for the entire tach-
f o r the resistance of the external circuit as
o m e t e r indicator circuitry is prescribed in
cuit within the test stand. By varying the in-
21. Dc Volts-Millivolts Meter Calibrating
put between 0 and 50 dc millivolts, the meter
Binding Posts
can be checked at different points on the scale.
The dc volts-millivolts meter calibrating bind-
19. Field Dc
Ammeter Calibrating Binding
i n g posts (11), located directly under the dc
Posts
volts-millivolts meter (4) in the center of the
meter panel, are a threaded two-piece post as
T h e field dc ammeter calibrating binding
p o s t s (9), located directly under the field dc
calibrating the dc volts-millivolts meter. With
ammeter (2) near the left hand end of the
t h e dc volts-millivolts range selector switch
meter panel, are a threaded two piece post as
(20) set in either the "9V" position or "900MV"
position, the meter can be calibrated by apply-
calibrating the field dc ammeter. With the se-
ing the same amount of dc voltage which was
lector switch (17) set between "5A (X1)" and
selected on the switch (20) to the calibrating
"15A (X3)" positions or between "15A (X3)"
a n d "30A (X6)" positions, the meter can be
binding posts. To take readings on the meter, it
is necessary to place the dc volts-millivolts mo-
calibrated by connecting a 50 millivolt dc input
to the calibrating binding posts (9), with allow-
m e n t a r y - o n switch (21) in the "READ" posi-
tion. A correctly calibrated meter will indicate
ternal circuit as compared with the resistance
the amount of applied dc voltage.
of the meter circuit within the test stand. By
varying the input between 0 and 50 dc milli-
The dc voltmeter calibrating binding posts
v o l t s , the meter can be checked at different
( 1 2 ) , located directly under the dc voltmeter
points on the scale, and by reversing the po-
( 5 ) near the right hand center of the meter
larity of the input, the meter can be checked
p a n e l , are a threaded two-piece post as de-
in both directions.
20