MIL-DTL-9398D
4.5.10 Vibration failure. The test of 4.5.9 shall be conducted except that the ambient
temperature shall be 350 ºF ± 9 ºF (177 °C ± 5 °C) and a test indicator (see 4.2.2) shall be used instead
of the 40-ohm load. The generator output shall be monitored during the entire period. At no time
shall the output voltage differ from the ambient room temperature value by more then 5 V, nor shall
there be any discernable oscillation of the indicator pointer caused by the generator vibration. After
vibration and after the generator has cooled to room temperature, the generator shall be subjected to
and meet the requirements of 4.5.5.
4.5.11 Low temperature exposure. The generator shall be maintained at a temperature of
-85 ºF ± 9 ºF (-65 ºC ± 5 ºC) for a period of 48 hours to 72 hours. At the end of this period and
while the generator is still at that temperature, the torque required to rotate the generator shaft shall
be measured and shall not exceed 12 inch-pounds. No damage to the generator shall result from
this test.
4.5.12 High temperature exposure. The generator, operating a single test indicator (see
4.2.2), shall be subjected to an ambient temperature of 350 ºF ± 9 ºF (177 °C ±5 °C) for a period of
two hours while operating at a shaft speed of 4,200 RPM. At the end of this time, the temperature
shall be lowered to room temperature in a period of one hour. The generator shall be maintained
at room temperature for a period of one hour. This temperature cycle shall be conducted six times.
No damage to, or malfunction of, the generator shall result from this test. The generator shall then
be subjected to and meet the requirements of 4.5.3 and 4.5.5.
4.5.13 Altitude high temperature. The generator shall be connected to a load of three
40-ohm Y-connected resistances (see 4.2.3) and operated at 4,200 RPM for 20 hours at a
temperature of 302 ºF ± 9 ºF (150 ºC ± 5 ºC) at a pressure of 0.82 inches Hg (80,000 feet). The
generator output shall be monitored and the respective terminal voltages shall not differ by more
than 5 V from the output prior to this exposure. After return to room temperature and pressure for
at least four hours, the generator shall be subjected to and meet the requirements of 4.5.5.
4.5.14 Acceleration. The generator shall be connected to a load consisting of three 40-ohm
Y-connected resistances (see 4.2.3). The generator drive shaft shall be coupled to an electric motor
that starts with an initial acceleration of 400 revolutions per second per second. The generator shall
be subjected to this acceleration for 500 applications. The final speed of the motor on each
application shall be 2,000 RPM to 3,600 RPM. No damage to any part of the generator shall result
from this test.
4.5.15 Short circuit. The generator shall be connected to a load consisting of three 40-ohm
Y-connected resistances (see 4.2.3) and operated at 4,200 RPM. The three terminal voltages shall be
determined. The generator shall then be short circuited across all three terminals five times for a
period of one second each time. After the generator has been allowed to cool to room temperature, it
shall be subjected to and meet the requirements of 4.5.3 and 4.5.5.
4.5.16 Overspeed and reverse operation. The generator shall be connected to a load
consisting of three 40-ohm Y-connected resistances (see 4.2.3) and operated at 4,200 RPM. The
generator shall be operated with the specified load at 5,100 RPM for a period of five minutes, then in
reverse direction at 4,200 RPM for a period of one minute. After the generator has been allowed to
cool to room temperature, it shall be subjected to and meet the requirements of 4.5.5.
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