MIL-STD-981 Design, Manufacturing And Quality Standards For Custom Electromagnetic Devices For Space Applications

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MIL-STD-981C

5.6.7.3.4 Burn-in Applicable to Class S and B parts.

5.6.7.3.4.1 Transformers

5.6.7.3.4.1.1 Power burn-in (applicable for transformers with an output greater than 0.8 watts or

temperature rise exceeding 30°C). Devices shall be tested as follows:

a. Test duration: 96 hours minimum.

b. Test temperature: maximum rated ambient temperature. (See applicable specification)

c. Test voltages and currents: Rated input voltage and current at minimum rated frequency and at maximum rated load.

TABLE V. Group A screening tests for families 03, 04, 20, 21, 36, 37,40 and 41 respectively (see

5.6.7.3.3).

Examination/Test

Class

Applicable Military

Specification

Inspection

Subgroup I Thermal shock

Temperature rise 1/

Burn-in

Seal (when applicable) Induced voltage

Dielectric withstanding voltage (at atmospheric pressure) Insulation resistance

Electrical characteristics Corona discharge (when specified)

Radiographic inspection

x x x x x x

x x x

x x x x x x

x x x

See 5.6.7.3.3.1

MIL-PRF-27

See 5.6.7.3.4

MIL-PRF-27

See appendix B

100 percent

Subgroup II Visual and dimensional

examination (external)

MIL-PRF-27

100 percent

1/ Test 2 units for temperature rise per applicable specification if temperature rise is not known.

2/ When specified.

5.6.7.3.4.1.2 No load burn-in (applicable for transformers with an output equal to or less than 0.8 watts

and temperature rise less than 30°C). Devices shall be tested as follows:

a. Test duration: 96 hours minimum

b. Test temperature: Maximum rated ambient temperature. (See applicable specification)

c. Test voltages and current: Rated input voltage and current at minimum rated frequency with no load.

5.6.7.3.4.2 No-load burn-in for Inductors: Devices shall be tested as follows:

a. Test duration: 96 hours minimum

b. Test temperature: Maximum operating temperature. (See applicable specification)

c. Test voltages and currents: Not applicable.