MIL-DTL-62186C
4.3.5.10 Transient load test. Connect the alternator to a test circuit as specified in
figure 11. Subject the alternator to ten motor load applications and removals at 2400 and
8000 rpm, and at each speed per figure 1. The transient load requirements shall be in accordance
with figure 1.
4.3.5.11 Efficiency test. Connect the alternator to a test circuit as specified in figure 10.
With the alternator at a speed of 8000 rpm, the output current at 650 A, the output voltage at
28 Vdc at the alternator terminals, the inlet oil temperature at 225F (107C), and using the
following equation, the efficiency of the alternator shall be at least 65%.
Efficiency (n) = 0.001341 EA x IA x 100
SHP
n = Efficiency at terminals in %.
EA= Alternator terminal voltage.
IA= Alternator current in A.
SHP= Shaft horsepower input to alternator.
4.3.5.12 Proof pressure. Cap and seal the oil inlet port of the alternator. Connect a
regulated supply of dry nitrogen to the oil outlet port and pressurize to 200 psi (1379 kPa) in
5 minutes. With the nitrogen supply turned off, verify that the pressure drop is not greater than
10 psi (69 kPa) in 1 minute.
4.3.5.12.1 Proof pressure acceptance test. With the oil inlet capped and sealed, connect a
regulated supply of dry nitrogen to the oil outlet port. Pressurize to 150 psi (1034 kPa), and shut
off the supply. Verify that the pressure drop is not greater than 10 psi (69 kPa) in 1 minute.
4.3.5.13 Torsion. Complete the tests as specified in 4.3.5.13.1 through 4.3.5.13.3.
4.3.5.13.1 Natural frequency test. Support the alternator and drive shaft system in the
normal bearings. Rigidly attach the rotor and shafting at the driven end to a reaction flywheel
having a mass moment of inertia of not less than 20 times that of the alternator rotating system.
The natural torsional resonant frequency of the rotor and the shafting system shall be between
100 and 140 Hz.
4.3.5.13.2 Vibratory torque test. Attach the alternator to an engine-transmission
assembly and drive the alternator to obtain a vibratory torque of 2100 pound-force inches (lbf-in)
(237.3 Newton-meters (N-m)). With positive torque not greater than 2100 lbf-in (237.3 N-m),
drive the alternator at a frequency between 20 and 25 Hz for a period which produces
12 000 torque reversals. There shall be no evidence of damage.
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