MIL-DTL-9398D
4.5.4 Phase rotation. The generator shall be properly connected to a test indicator (see 4.2.2).
The wiring shall be arranged so that generator terminals marked A and B shall be connected to the
indicator terminals marked A and B respectively. The C terminal of the indicator shall be grounded.
The indicator shall indicate positively when the generator drive shaft is rotated in a counterclockwise
direction (looking at the spline end of the shaft).
4.5.5 Voltage. The generator shall be operated at a drive shaft speed of 4,200 RPM with a
load consisting of three 40-ohm Y-connected resistances (see 4.2.3). The three terminal voltages
shall be 21 V ±1.5 V when measured at the generator terminals. When the generator is similarly
operated at a shaft speed of 1,000 RPM with a load of three 20-ohm Y-connected resistances, none
of the three terminal voltages shall be less than 3.5 V. The respective values shall be recorded and
retained for reference.
CAUTION: Provide adequate ventilation during the following test.
4.5.6 Oil leakage. The generator shall be mounted on a fixture with the drive shaft horizontal
and one of the drain holes at the bottom. Oil in accordance with MIL-PRF-7808 at a temperature of
250 ºF +18 ºF/-0 ºF (121 ºC +10 ºC/-0 ºC) and a pressure of one pound per square inch shall be applied
to the drive shaft end of the generator while the generator is operated at 4,200 RPM with a load of
three 40-ohm Y-connected resistances (see 4.2.3.). The quantity of oil that leaks out through the
bottom drain hole in a one-hour period after the first drop appears shall not exceed 2 cubic centimeters
(cc). If no oil appears after one hour of operation, the test shall be considered complete.
4.5.7 Low temperature operation. The generator shall be placed in a chamber, the
temperature of which shall be controllable. The temperature of the circulating air shall be reduced to
-67 ºF ± 9 ºF (-55 ºC ± 5 ºC) and held at this temperature for the duration of the test. The generator
shall be kept in the chamber for not less than four hours after the temperature of -67 ºF (-55 °C) is
reached before the test is started. The torque required to rotate the generator shaft shall not exceed
8 inlb. No damage to the generator shall result from this test.
4.5.8 High temperature operation. The generator shall be made to operate two test
indicators (see 4.2.2) at a generator speed of 4,200 RPM at ambient room temperature (see 4.2.1).
The generator terminal voltages shall be recorded. The generator shall then be subjected to a
temperature of 350 ºF ± 9 ºF (177 °C ± 5 °C) for two hours and while at this temperature shall be
made to operate continuously the same two test indicators at the same generator speed. The
voltage output at high temperature shall not differ from the ambient room temperature voltage
output by more than 5 V. No damage to any part of the generator shall result from this test. Upon
return to room temperature, the generator shall be tested and meet the requirements of 4.5.5.
4.5.9 Vibration. The vibration test shall be conducted at room temperature in accordance
with MIL-STD-810, test method 514.5, test procedure IV, tailoring category 22. The generator
shall be connected to a standard load (see 4.2.3) and operated at 4,200 RPM. The generator,
operating at 4,200 RPM shall be vibrated for three hours. After the vibration, the generator shall
be subjected to and meet the requirements of 4.5.3 and 4.5.5.
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