MIL-PRF-81F
4.6.8 Terminal strength (see 3.11). A 4-pound force shall be applied between each terminal and the base. The
force shall be applied parallel to the terminal extension, and shall be increased gradually to 4 pounds and held at
that value for not less than 10 seconds.
4.6.9 Torque (see 3.12). The torque required to start and maintain rotation of the rotor shall be measured by a
gradually applied force sufficient to turn the rotor through at least one complete rotation.
4.6.10 Fatigue (see 3.13). Capacitance, at maximum capacitance setting, shall be measured as specified in
4.6.5. The rotors of the capacitors shall be continuously rotated through the complete range (360 degrees) in
alternating directions at a rate of approximately 20 cycles per minute for a period of 5 minutes. The driving
mechanism used in this test shall include a flexible coupling to prevent development of excessive pressures caused
by misalignment of the driving shaft and setting, and the torque shall be measured as specified in 4.6.9, respectively.
4.6.11 Life (see 3.14).
4.6.11.1 For qualification inspection. Capacitance shall be set at 80 percent to 90 percent of maximum
capacitance and measured as specified in 4.6.5. A dc potential of 50 percent rated voltage upon which a peak
alternating potential of 50 percent rated voltage at a frequency of 100 Hz or less is superimposed, shall then be
applied to the capacitors for 1,000 hours ±12 hours at a temperature of 85°C ±2°C. Upon completion of the test,
capacitors shall be returned to standard test conditions without disturbing the initial capacitance setting. Insulation
4.6.11.2 For quality conformance inspection. The life test shall be conducted as specified in 4.6.11.1.
4.6.12 Shock, specified pulse (see 3.15). Capacitors shall be tested in accordance with
method 213 of MIL-STD-202. The following details and exceptions shall apply.
a.
Special mounting means: Capacitors shall be rigidly mounted on a mounting fixture by the normal mounting
means.
b.
Number and direction of applied shocks: Thirty shocks, ten blows in each of three mutually perpendicular
planes (five in each of two directions). The test planes shall be perpendicular to the normal mounting axis,
perpendicular to the mounting axis with the capacitor body rotated 90 degrees, and parallel to the mounting
axis.
c.
Test-condition letter: I.
d.
Electrical-load conditions: During the test, a potential of 125 percent of the rated dc voltage (see 3.1) shall be
applied between the terminals of the capacitor.
e.
Measurements during shock: During the test, observations shall be made to determine intermittent contacts
of 0.5 ms or greater duration or arcing or other indication of any open or short circuiting or evidence of
mechanical damage.
f.
Examinations after test: Capacitors shall be visually examined for evidence of breakdown, arcing, and
mechanical damage.
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