MIL-DTL-25955A
4.6.13 Contact resistance test (see 3.6.13). Resistance of contacts shall be determined in accordance
with MIL-STD-202, method 307, and the following details:
a. Voltmeter - ammeter shall be employed.
b. Ambient temperature shall be 25° ±3°C (77°F ±5°F).
c. Wire of AWG size corresponding to contact size shall be connected to contact terminations in the
fashion intended for service application.
d. The contact resistance shall be measured after the first insertion of pin into socket.
e. The voltage probes shall contact the wire at least 0.015 inch (0.38 mm) behind the contact where
crimp connections are employed. The probe shall not make direct contact with the contacts.
Solder termination contact voltages shall be picked up at the exposed junction of the contact and
wire nearest the engaging end.
f. Depth of insertion of loose pins into loose sockets shall be 0.188 ±.010 inches (4.78 ±0.25 mm).
g. Number of loose pins and sockets tested shall be five.
4.6.14 Insert retention test (see 3.6.14). Connectors less grommets shall be subjected to axial loads in
each direction separately as specified herein. The loading shall be increased gradually at an approximate
rate of 1 pound per second until specified load is reached. The specified load shall be maintained for 5
seconds. The load-applying device may be shaped as necessary to reduce the pressure at individual
points.
4.6.15 Crimp retention test (see 3.6.15). Twenty-five socket contacts, five pin contacts, and pin
contacts shall be crimped to suitable wires. Contacts shall be proportioned among the wire sizes
specified. The dimensions of the contact crimping tools shall be in accordance with figure 4. The
contacts shall be secured such that no support is given to the crimp joint. A measured axial tension load
shall then be applied to the contacts and wires at an approximately uniform rate of 1 pound per second.
4.6.16 Arc resistance test (see 3.6.16). Disc specimens of insert material conforming to ASTM-D5948,
shall be tested in accordance with ASTM-D5948 employing the circuit shown on figure 5 and details as
follows:
a. 12 KV (minimum) transformer.
b. KVA rating of transformer not specified, but 10 Ma (RMS) must be obtainable.
c. Sufficient external resistance may be added in the leg of the circuit that is not grounded, if
necessary, to obtain the required 10 Ma across the electrodes in air (not reading on test specimen).
d. Cable on resistance side shall be supported in air.
e. Floor or chamber shall have a one-inch thick insulating sheet for supporting the specimen under
test.
f. A millimeter shall be placed in the circuit between the ground and the arc electrode.
g. Specimen shall be cleansed with a clean cloth, dampened with alcohol and dried with a soft, clean,
dry cloth before each test.
h. Arc electrodes shall be cleansed with a soft, clean cloth dampened with alcohol and dried with a
soft, clean dry cloth before each test.
i. Primary voltage shall be controlled with a variable tap auto transformer.
j. Relative humidity shall be between 30 and 40 per cent.
k. Interrupter must cause an arc to flow ¼ second and cease 1-3/4 seconds repetitively during the first
minute and to flow ¼ second and cease ¾ second repetitively during the second minute.
l. The electrodes shall consist of two steel rods 0.186 inch (4.72 mm) diameter, equipped with
tungsten wire tips 0.060 inch (1.52 mm) in diameter, which have conical points with 60° included
angle. The electrodes shall be mounted to, and insulated block at 45° to the vertical and shall be
adjusted to give a gap of 0.320 inch (8.13 mm). Both electrodes shall be in the same horizontal and
vertical planes.
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