MIL-PRF-81F
4.6.3 Barometric pressure (reduced, qualification only) (see 3.6). Capacitors shall be tested in accordance with
method 105 of MIL-STD-202. The following details shall apply.
a.
Mounting: Normal mounting means.
Test condition: D (100,000 feet), and when applicable (see 3.1), condition B (50,000 feet).
b.
Tests during subjection to reduced pressure: Unless otherwise specified (see 3.1), a potential equal to the
c.
rated dc voltage shall be applied for not less than 3 seconds ±2 seconds between the terminals of the
capacitors.
4.6.4 Insulation resistance (see 3.7). Capacitors shall be tested in accordance with method 302 of MIL-STD-202.
The following details shall apply;
a.
Test condition: Rated voltage, but not to exceed 500 volts.
b.
Special conditions: If failure occurs at a relative humidity above 60 percent, the insulation resistance may be
measured again at a relative humidity of 50 percent ±5 percent.
c.
Point of measurement: Terminal to terminal.
d.
Electrification time: Shall not exceed 1 minute.
4.6.5 Capacitance (see 3.8). Capacitors shall be tested in accordance with method 305 of MIL-STD-202. The
following details shall apply.
a.
Test frequency: 1 MHz ±100 kHz.
b.
Limit of accuracy: ±2 percent or 0.5 pF, whichever is greater.
4.6.6 Dissipation factor (see 3.9). The dissipation factor of capacitors shall be measured at both maximum and
minimum capacitance setting at a frequency of 1 MHz ±100 kHz. The accuracy of measurement shall be within ±10
percent of the limit (see 3.9). The voltage applied shall be less than 30 volts peak.
4.6.7 Temperature coefficient and capacitance drift (see 3.10).
4.6.7.1 Temperature coefficient. Capacitance-change measurement at 80 percent to 90 percent of maximum
rated capacitance setting shall be made at the temperature specified in table VI and at a frequency between 0.1 MHz
and 1.2 MHz. Each measurement shall be made after the capacitor has reached thermal stability. (Thermal stability
has been reached when no further change in capacitance is obtained between two successive measurements taken
at 5-minute intervals.)
TABLE VI. Capacitance-change measurements.
Sequence
Temperature
25°C ±2°C
Step 1
Start at
-55°C ±2°C
Step 2
Reduce to
25°C ±2°C
Step 3
Return to
Step 4
Raise to
85°C ±2°C
Step 5
Return to
25°C ±2°C
4.6.7.2 Capacitance drift. Calculation of capacitance drift shall be based on the maximum deviation between any
two of the three measurements of capacitance at 25°C (see table VI).
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