TM 55-2925-236-40
(3) Increase the speed of the driving motor
ous conditions. There should be no sparking ex-
to 11,000 rpm. The generator must operate al
cept for the fine pinpoint sparking at the genera-
this speed for five minutes without mechanical
tor brushes.
failure, the throwing of varnish, or impairment
Note. For any speed within the speed range,
of electrical performance.
the field current must increase with increases in load.
(4) At the end of the five-minute overspeed
run, reduce the speed to 6000 rpm. Apply rated
load of 300 amperes.
Line
Voltage
(5) Operate the starter generator for one
0
30
4400
minute and check the electrical performance. The
150
30
4400
results should compare with those observed in
300
4400
30
0
30
6000
150
30
f. Polarity Check.
6000
300
30
6000
(1) Operate the starter generator at rated
0
30
8(MO
speed and load conditions. Connect the voltmeter
150
8000
30
leads to starter generator terminals B+ and E-
300
8000
30
observing proper polarity.
(2) If the voltmeter connections must be re-
e. Overspeed.
versed to obtain a reading, the polarity of the
(1) Perform this test while the starter gen-
starter generator is reversed. In this case, flash
erator is hot as a result of testing.
the field in the proper direction as described in
(2) Open all load switches and the field
switch. Operate the generator at no load.
4-5
