MIL-PRF-19978K
4.7.19 Temperature coefficient (see 3.23) (characteristic P only, see 3.1). Capacitance measurements shall be
made after the capacitors have been stabilized at each of the following temperatures: -65C, +25C, and the high
ambient test temperature (see 3.1). Stability shall be indicated when no change exists in two capacitance
measurements made at 5-minute intervals. Temperature coefficient shall be computed from the following formula:
6
(C2 - C1) 10
temperature coefficient in ppm/C.
Where:
TC
=
=
TC
capacitance at +25C in pF.
C1
=
(T2 - T1) C1
C2
=
capacitance at test temperature in pF.
+25C.
T1
=
T2
=
test temperature in degrees C.
TABLE XVII. Life test in hours
NON-ER capacitors
Characteristic
Qualification
Group B
240 +48, -0 1/
240 +48, -0 1/
All characteristics except M
M
2,000 +72, -0
2,000 +72, -0
ER capacitors
Style
Qualification
Group B
Extended life
CQR39, 42, and 43
240 +48, -0
240 +48, -0
---
FRLs M, P, R, S, for all styles
2,000 +72, -0
2,000 +72, -0
4,000 +72, -0
except CQR39, 42, and 43
1/ Test time for characteristic K tubular capacitors with voltage rating of 1,000 volts shall be
500 12 hours.
4.7.20 Life (see 3.24).
4.7.20.1 Life test (qualification inspection). Capacitors shall be tested in accordance with method 108 of MIL-
STD-202. The following details and exceptions shall apply:
a. Distance of temperature measurements from specimens, inches: Not applicable.
b. Test temperature and tolerance: At the applicable high-test temperature, +4°C, -0°C (see 3.1).
c. Operating conditions: Capacitors shall be subjected to 140 percent of the rated dc voltage. The surge
current shall be limited to between 5 milliamperes and 1 ampere. When necessary, a suitable current-
limiting resistor shall be used.
d. Test duration: See table XVII.
e. Measurements during and after exposure: At the conclusion of the test, the capacitors shall be returned to
the inspection conditions specified in 4.3 and shall be visually examined for evidence of mechanical
damage and obliteration of marking; insulation resistance at +25°C, capacitance, and dissipation factor
4.7.20.2 Life test (group B inspection) (see 3.24). Except as specified in the following, capacitors shall be tested
as specified in 4.7.20.1.
a. Test duration: See table XVII.
b. Measurements during and after exposure: Measurements, as specified in 4.7.20.1e, shall be taken at the
following intervals of exposure: During the first hour; 240 hours +48 hours, -0 hours; and where applicable,
1,000 hours +48 hours, -0 hours; and 2,000 hours +72 hours, -0 hours.
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