MIL-PRF-15160K
4.7.2 Current-carrying capacity. Unless otherwise specified (see 3.1), fuses shall be subjected to an ac or dc
current of 110 percent of rated current at any convenient voltage within the rating of the fuse. The current shall be
maintained for not less than 30 minutes after the temperature of each fuse has stabilized. Stabilization shall be
considered to have occurred when no individual fuse temperature rise reading of 4 consecutive readings taken at 5
minute intervals exceeds the average reading of these 4 readings by more than 2° C and no indication of increasing
temperature rise is observed. This average temperature rise reading shall be deemed to be the temperature rise of
the fuse. The temperature of the fuse case or body and of the terminals shall be measured by thermocouples (wire
size 28 AWG to 32 AWG) or by using the thermometer method. Each fuse shall be mounted in a standard single
pole, open-type fuseholder having a corresponding electrical rating. Fuseholders and fuseclips may be selected from
MIL-PRF-19207. When two or more fuses are tested in series, the fuseholders shall be located so that there will be a
spacing of not less than 6 inches between any two fuses under test. The wire connecting the fuseholders, ammeter,
and the source of supply shall be in accordance with A-A-59544. The wire length and size shall be as shown in table
TABLE IX. Size of test leads.
Wire
Fuse rating
Circular-mil
amperes
size
Length (ft)
AWG size
0 - 30
2
8
31 - 60
2
4
61 - 100
2
1
101 - 200
2
200,000
201 - 400
4
500,000
401 - 600
4
1,000,000
4.7.3 Resistance. Resistance shall be calculated from the voltage drop measured between the terminals of the
fuse at 10 percent or less of rated current using a high impedance voltmeter, a double Kelvin Bridge, Wheatstone
Bridge, or other measuring means. Fuses shall meet the requirements specified in 3.8.
4.7.4 Terminal strength. Unless otherwise specified (see 3.1), terminals shall be tested in accordance with method
211 of MIL-STD-202, as applicable. Forces shall be as specified (see 3.1), and shall be applied to individual
terminals as follows.
a. Pin type terminals: Test condition A.
(1)
Along terminal axis.
(2)
Perpendicular to terminal axis.
b. Ferrule and knife blade type terminals: Test condition E.
(1)
Torque.
Fuse terminals shall meet the requirements specified in 3.9.
4.7.5 Overload interrupt. Fuses shall be subjected to the percentage of rated alternating current and voltage
specified (see 3.1). Unless otherwise specified for qualification, and group B inspection, this test shall be performed
at standard ambient conditions only. Opening time measurements shall be made with an oscillograph for periods
shorter than 1 second; a synchronous timer may be used for measurements longer than 1 second and a stop watch
is suitable for measurements of longer than 10 seconds. Unless otherwise specified (see 3.1), the number of fuses
shall be divided evenly for various overloads and temperature conditions. For rated voltage test, the fuses shall be
left in the energized circuit for 1 minute minimum after interruption without any indication of reclosing. Fuses shall
meet the requirements specified in 3.10.
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