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ELECTRICAL
201
Service Data
(continued).
After generator has been raised to operation temperature
by
running it at the above specified speed and time rates, at
steady 12 voltage, read the amperage at every generator
speed increment: each reading will represent a point of the
output curve of the generator as shown in fig. 321.
-
Heating test:
Speed, for abt. 1 hOUI and 45 min.
Current delivery to resistor (at 14 Volts)
l
field frame. not above
Overheating
commutator, not above
- Ohmic resistance test (at 68° F - 20° C):
Armature resistance
Field winding resistance
- Mechanical characteristics test:
Load of springs on new brushes
Maximum commutator out-of-round
Mica undercut depth
4,500
r.p.m.
15.5 to 16.5 Amps
66
0
F (30
0
C)
149
0
F
(65
0
C)
0.135 to 0.155 ohms
7.70 to 8.10 ohms
1.3 to 1.6 lbs (0.60 to 0.72 kg)
.0004" (0.01 rom)
.0236" to .0275" (0.6 to 0.7 rom)
Lubrication.
Drive end ball bearing .
Commutator end head oiler
FIAT MR 3
grease
FIAT engine oil
BENCH
TESTING
To check the generator efficiency, carry out
operation tests, as well as electrical and mechanical
characteristics tests according to the following
directions.
Fig. 319 • Wiring diagram for motoring tes1.
G. Generator. - V. Voltmeter, 15 V scale. - A. Ammeter, 10 A
scale. - B. Battery capable of supplying a voltage slightly above 12 V
during a discharge of 5 A. - R. Plate type rheostat for regulating
the batlery voltage, 100 A capacity. variable resistance of 0.2 to 20
n.
B
=
J
G
Output test at 12 V steady tension (at 68
0
F - 20
0
C).
NOTICE - Prior to plotting the output curve, make
sure that brushes are thoroughly seated in com-
mutator bore.
Install generator on test bench and couple it with
a motor, whose speed may be varied at will by
small degrees.
Wire up according to diagram fig. 320.
Before starting the test, run generator for I hour
and 45 min. at 4,500 r.p.m., delivering a 15.5 to
16.5 A - 14 V current to a resistor.
Stop motor.
'--"M~i/\/C---o
61
'-------<>
51
Fig. 318
~
Generator wiring diagram.
Before starting any test, it is advisable to have
all test equipment and gauges ready for use.
It
is recommended to strictly follow the directions
given for each test.
Motoring test (at 68
0
F • 2()O C).
This is the first and simplest test for a quick gen-
erator check.
Wire up according to diagram fig. 319.
Feed generator with a 12 V d.c. supply and check
that current draw is 4.5 to 5.5 A at 1,400 to 1,600
r.p.m.
Operation Tests.
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