MIL-DTL-3702F
4.7.3.6 Environmental.
4.7.3.6.1 Low temperature. The low temperature test specimen, a 4-foot (1.22 meters) length of
unshielded or shielded cable with the shielding removed, shall be prepared and tested as follows.
4.7.3.6.1.1 Preparation. A 5-pound weight shall be attached to one end of the specimen. The other
end shall be attached to a 1inch (25.4 mm) diameter, smooth, cylindrical mandrel. The specimen, not
wound on the mandrel, shall be placed in a cold chamber and subjected to minus 65±5°F for 24 hours.
4.7.3.6.1.2 Flexing. Following the refrigeration period, while still in the cold chamber, the specimen
shall be wound around the attached mandrel against the pull exerted by the weight at the rate of 20 turns
per minute, for not less than 5 complete wraps or turns. Examination shall then be made for evidence of
cracking, breaking, or separation.
4.7.3.6.1.3 Voltage application. The specimen shall be immediately subjected to the maximum
voltage test specified in 4.7.3.2. The specimen may be removed from the cold chamber for this test.
4.7.3.6.2 High temperature and altitude. The high temperature and altitude test specimen shall
consist of a 4.5 foot (1.37 meters) length of cable prepared as specified on figure 4. The test assembly
mounted on the mandrel shall be placed in a circulating air oven capable of reaching 600±8 °F for high
temperature cable, 450±4°F for medium temperature cable, and 250±4°F for low temperature cable within
a period of not less than 1 hour, nor more than 3 hours. The specimen shall be subjected to this
temperature for a period of 125 hours, except that, for high temperature cable, the test shall be conducted
at 450°F during the first 50 hours and the last 25 hours. The high temperature and altitude tests shall be
conducted as follows.
4.7.3.6.2.1 Voltage application. A potential of 12 kilovolts rms at 60 Hz shall be applied for the first
and last 5 hours of the 125-hour test specified in 4.7.3.6.2. The initial voltage application shall be made
at room temperature simultaneously with the start of the oven heating units. At the conclusion of this test
and after allowing the specimen to cool to room temperature, the insulation braid and sheath shall be
examined for damage that might affect subsequent performance.
4.7.3.6.2.2 Altitude. At the conclusion of the voltage application test specified in 4.7.3.6.2.1, and
after cooling to room temperature, the test medium and high temperature cable specimens, as set up on
figure 4, shall be placed in an altitude chamber and the pressure reduced to the equivalent of 70,000 feet
plus 5,000 minus 0 feet altitude, and maintained within these limits during the voltage application test
specified in 4.7.3.6.2.2.1.
4.7.3.6.2.2.1 Voltage application. A potential of 12 kilovolts rms at 60 Hz shall be applied between
the cable conductor and the conduit assembly as shown on figure 4 for a period of 2 hours. The
specimen shall then be inspected for evidence of insulation rupture, cracking, or other damage.
4.7.3.6.3 Hot oil. The hot oil test specimen shall consist of two 4-foot (1.22 meter) lengths of
unshielded or shielded cable with the shielding removed, and shall be prepared and tested as follows.
4.7.3.6.3.1 Procedure. The specimens shall each be wound on a mandrel in the manner described
in 4.7.3.6.7.1. The average diameter of the cable shall be determined for that portion of the free ends of
the cable specimen which are submerged during the immersion period specified in 4.7.3.6.3.2. To obtain
the average diameter, measurements shall be taken 90 degrees apart at the locations selected.
21
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business