MIL-PRF-23419H
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4.7.6.2 Maximum current clearing (I t)(see 3.10.2). The maximum clearing I t shall be determined from
an oscillogram showing the current trace or by other equivalent means. It is suggested that UL Standard
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248-1 be used for guidance only in determining I t but is not intended for compliance. Fuses shall be
subjected to rms symmetrical currents with a tolerance of +20, -0 percent. The power factor shall be 95
to 100 percent. The closing angle shall be essentially at zero of the voltage wave (maximum offset) or
later, so as to produce start of arcing within 30 electrical degrees prior to system peak voltage. The test
voltage shall be not less than the rated voltage of the fuse (see 3.1). The maximum peak voltage
occurring during the interruption shall be not more than 3,000 volts. This voltage shall be measured with
an instrument having a frequency response that is linear from 50 Hz to 300 Hz.
4.7.6.3 Short circuit (see 3.10.3). Fuses shall be subjected to the tests at the current and voltage
specified (see 3.1). The dc tests shall be made using appropriate generating equipment as a source of
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power and with the rate of current rise for the test circuit adjusted for at least 3.25 x 10 amperes per
second. The ac tests shall be conducted using an ac supply of adequate capacity and shall be on a
single phase basis. Unless otherwise specified (see 3.1), the current shall be applied within ±10 degrees
of zero point of the voltage wave and the circuit power factor shall be 0.85 to 0.95. Short circuit currents
shall be determined by means of an oscillograph. Test circuits shall be calibrated for the specified current
with the applicable fuseholder (see 3.1) short-circuited.
4.7.8 Vibration (see 3.12).
4.7.8.1 Vibration, high frequency (see 3.12.1). The fuses shall be subjected to
vibration tests in accordance with method 204 of MIL-STD-202. The following details shall apply:
a. Mounting: In applicable fuseholder (see 3.1).
b. Test condition C.
c. One-half of the sample units shall be tested while carrying 100 percent of rated current and the
balance tested with no current. All sample units shall be tested for continuity as specified in
4.7.2 at the end of test.
4.7.8.2 Vibration, random (see 3.12.2). The fuses shall be subjected to vibration tests in accordance
with method 214 of MIL-STD-202. The following details shall apply:
a. Mounting: In applicable fuseholder (see 3.1).
b. Test condition I, letter E.
c. Duration shall be as specified (see 3.1).
d. One-half of the sample units shall be tested while carrying 100 percent of rated current and the
balance tested with no current. All sample units shall be tested for continuity as specified in
4.7.2 at the end of test.
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