TM 5-6115-400-35
CHAPTER 4
MAIN GENERATOR AND AUXILIARY EQUIPMENT
REPAIR INSTRUCTIONS
Section I. MAIN GENERATOR
64. General
The Electric Machinery Model 651853 alternating
current generator is a fully enclosed, fan-cooled,
revolving field, 3-phase alternator. The generator rotor
is driven directly by the engine flywheel through a
flexible coupling.
When driven at its rated speed of 1,800 rpm, the
generator will produce 200 KW (kilowatt) at 60 cycles
with a power factor of 0.8 and it will deliver 694 amperes
at 120/208 volts or 347 amperes at 240/416 volts.
When driven at 1,500 rpm, the generator will produce
167 KW at 50 cycles with a power factor of 0.8 and it
will deliver 580 amperes at 120/208 volts or 290
amperes at 240/416 volts.
65. Brush Tension Adjustment
Adjust the brush springs to obtain a brush tension
between 15 ounces minimum to 24 ounces maximum.
See figure 112.
66. Drying Out Generator Windings
a. If the generator set has been subjected to extreme
Figure 112. Brush tension adjustment.
dampness, a preliminary period of operation may be
required to thoroughly dry all generator windings. Use a
Note
megger to determine if drying out is necessary. Refer to
Before measuring the resistance of
the generator stator and rotor,
rotor.
disconnect all controls. Do not use a
Table 3. Insulation Limits
megger to check the rectifiers and
Minimum values when insulation resistance is taken at
other components installed in the
various ambient temperatures:
voltage regulator and excitation unit.
Stator
Rotor
b. To dry out the generator windings, first
Ambient
*Megohms
Ambient
*Megohms
15
C
39
15
C
58
brushes and connect an external source of field
20
C
32
20
C
47
excitation direct current to the brushes. Short circuit the
25
C
27
25
C
39
stator terminals and insert a current transformer and
30
C
22
30
C
32
ammeter, capable of reading full-load generator current,
35
C
18
35
C
27
in one of the shorting leads. Operate the generator at
*The megged values should equal or exceed the figures
rated speed (1,800 rpm) and apply sufficient field
given for the temperatures at the time of test.
excitation to develop rated full load stator current.
Operate under these conditions for sufficient time to
insure thorough drying of the windings as determined by
periodic measurements of rotor and stator insulation
resistance.
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