MIL-PRF-19207G
4.6.9.1 Insertion and withdrawal test. Where the fuse is retained in pressure or spring clips in the
fuseholder cap or body, the fuse shall be inserted in the clips and removed for a total of 100 operations.
One operation is defined as the insertion and removal of the fuse. This test may be performed
independently or as part of the operational sequence of 4.6.9.
4.6.10 Temperature rise. A test fuse shall be inserted in the fuseholder, and a thermocouple of No. 28
to No. 32 AWG shall be placed on each fuseholder terminal as close to the fuseholder body as
practicable. The fuseholder shall be energized at the maximum current rating of the fuse and at any
voltage within the fuseholder rating. Temperature rise shall be measured when a constant temperature
has been reached, as indicated by three successive readings taken at 10 minute intervals and differing by
not more than plus or minus 1°C. All sections of multisection fuseholders shall be tested simultaneously
(see 3.5.10). Accuracy of the indicating device shall be within plus or minus 2°C.
4.6.11 Short circuit. A test fuse as specified (see 3.1) shall be assembled in the fuseholder. The
fuseholder shall be inserted in a single-phase circuit and subjected to the short circuit test in accordance
multisection fuseholder need be tested (See 3.5.11).
4.6.12 Indicating lamp. With the fuseholder energized at maximum rated voltage, the indicating lamp
shall properly indicate a "blown" fuse for 100 hours. Observations shall be made from a distance of 10
feet in any direction up to 45 degrees from the mounting axis of the fuseholder and in an ambient
illumination of 50 foot-candles. For groups A and C examination and tests, fuseholders shall be
energized at highest and lowest voltages only long enough to show that the "blown fuse" indicator circuit
is operating. For group C tests, the indicating lamp test shall be conducted on samples previously
submitted to the shock and vibration tests. A "blown fuse" may be assembled into the fuseholder if
necessary to complete the indicating circuit (see 3.5.12).
accordance with method 201 of MIL-STD-202. The following details shall apply:
a. Fuseholder shall be assembled with a test fuse.
b. The fuseholder shall be rigidly mounted by its normal mounting means.
Monitor with either circuit specified in method 310 of MIL-STD-202 or with an equivalent circuit
c.
capable of indicating a 10 µs opening of contacts. All fuseholders vibrated simultaneously may
be connected in series and monitored simultaneously. In the event of opening of contacts in
excess of 10 µs fuseholders shall be removed from the circuit until the defective one is found and
removed. All others shall be reinserted and the test continued.
d. Fuses which open during this test shall be replaced and the test continued.
4.6.14 Mechanical shock (see 3.5.14). Fuseholders shall be tested in accordance with method I (see
4.6.14.1) or method II (see 4.6.14.2), as specified (see 3.1). Contact opening shall be monitored with a
relay calibrated to drop on a 0.020-second interruption to its coil supply or by an equivalent timing device.
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