MIL-C-25F
4.6.3 Insulation resistance (see 3.6). Capacitors shall be tested in accordance with method 302 of MIL-STD-202.
The following details shall apply:
a. Test potential: A potential equal to the +40°C rated dc voltage or 500 volts dc, whichever is less, shall be
applied.
b. Points of measurement:
(1) Terminal to terminal: Insulation resistance shall be measured between terminals at the applicable high-
test temperature specified in table II and at +25°C, or corrected thereto. For
conformance inspection, the measurement at the high-test temperature is required
only for specimens which shall be subjected to the life test.
(2) Terminal to case: When the case is not a terminal, the measurement of the insulation resistance shall be
made between each terminal and the case at +25°C, or corrected thereto.
4.6.4 Capacitance (see 3.7). Capacitors shall be tested in accordance with method 305 of MIL-STD-202. The
following details shall apply:
a. Test frequency: 1,000 ± 100 Hz for capacitors when nominal capacitance does not exceed 1 microfarad and
whose rated dc voltage does not exceed 3,000 volts. For capacitors not within these limits, measurements
shall be made at a frequency of 100 ± 10 Hz.
b. Limit of accuracy: Shall be within ± 2 percent.
4.6.5 Dissipation factor (see 3.8). The dissipation factor of each capacitor shall be measured at a voltage not
greater than 20 percent of the rated dc voltage. If the nominal capacitance does not exceed 1 microfarad, and if the
rated dc voltage does not exceed 3,000 volts, measurement shall be made at a frequency of 1,000 ± 100 Hz.
Measurements on capacitors not within these limits shall be made at a frequency of 100 ± 10 Hz.
4.6.6 Barometric pressure (reduced) (qualification inspection only) (see 3.9). Capacitors shall be tested in
accordance with method 105 of MIL-STD-202. The following details and exceptions shall apply:
a. Method of mounting: Capacitors shall be securely fastened by normal mounting means.
b. Test condition: Unless otherwise specified (see 3.1), B.
c. Tests during subjection to reduced pressure: Unless otherwise specified (see 3.1), a potential equal to 125
percent of rated dc voltage shall be applied for at least 1 minute between each terminal and every other
terminal in turn, and between the case and each terminal not connected to the case. A suitable means shall
be used to detect momentary or permanent breakdown.
4.6.7 Vibration (Low frequency) (see 3.10). Capacitors shall be tested in accordance with method 201 of MIL-
STD-202. The following details and exceptions shall apply:
a. Tests and measurements prior to vibration: Not applicable.
b. Method of mounting: Securely fastened by normal mounting means.
c. Duration of vibration: 3 hours (60 minutes in each direction).
d. Tests and measurements during vibration: during the last 30 minutes of vibration in each direction, an
electrical measurement (see 6.14) shall be made to determine intermittent contacts or open-circuiting or
short-circuiting.
e. Examination after vibration: Capacitors shall be visually examined for evidence of mechanical damage.
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