MIL-DTL-55021D
4.6.3 Cold bend. Specimens of the finished cable shall have each conductor stripped, approximately
1 inch at each end, to the bare conductor and shall have one end attached to a mandrel and the other
end weighted. After conditioning for 4 hours at a temperature of -40±2 °C, and while maintained at this
temperature, the cable shall be wrapped around a mandrel having a maximum diameter that is 15 times
the finished cable diameter at a uniform rate of 15 revolutions per minute (rpm) for three complete turns.
After bending and before straightening, the cable shall be subjected to the appropriate dielectric strength
test specified in 4.6.2.
4.6.4 Spark test. The spark test shall be conducted in accordance with method 6211 of
FED-STD-228. The spark test voltage shall be 1,500 volts (rms).
4.6.5 Dielectric immersion (jacketed or shielded and jacketed cable). The cable sample shall be
immersed in tap water containing .5 percent, by volume, of a suitable wetting agent, except for 6 inches of
each end. The cable shall be soaked for a minimum period of 4 hours in the water solution maintained at
25 °C. The shield of the shielded and jacketed cable or the conductors of the jacketed cables shall be
electrically connected and subjected to a potential of 2,000 volts (rms) between them and the water
solution.
4.6.6 Heat resistance. The cable specimen shall be placed in a temperature-controlled chamber and
heated to the temperature and for the period specified in the applicable specification sheet. The cable
specimen shall then be removed from the oven and allowed to return to room temperature. The length of
exposed conductor, if any, at each end of the specimen shall be considered as shrinkage of the
insulation. In no case shall the shrinkage at either end exceed the maximum value specified in 3.6.7.
After 1 hour at room temperature, the cable specimen shall be wound 2 close turns around a mandrel
having a maximum diameter that is 10 times the cable diameter. While in the wound position, the cable
shall be subjected to the dielectric test of 4.6.2.
4.6.7 Low-temperature storage. The cable specimen shall be placed in a temperature chamber at a
temperature of -62 °C for a minimum of 72 hours. Upon completion of the 72-hour exposure, the cable
shall be allowed to stabilize at normal room temperature and then shall be subjected to the dielectric
strength test of 4.6.2.
4.6.8 Conductor continuity. An ohmmeter or other suitable low-voltage device shall be used to check
the continuity of each conductor. There shall be no indication of discontinuity.
4.6.9 Jacket tensile strength and elongation. Jacket materials requiring tensile strength and
elongation testing shall be tested in accordance with ASTM D3032, using 1-inch bench marks, a 1-inch
initial jaw separation, and a jaw separation speed of 2 inches per minute.
4.6.10 Jacket concentricity. The minimum wall thickness of a cross section of the extruded jacket
shall be located and recorded. The maximum wall thickness of the jacket in this same cross section shall
be measured and recorded. The ratio of the minimum wall thickness to the maximum wall thickness
times 100 shall be defined as the percent concentricity.
4.6.11 Jacket wall thickness. The jacket wall thickness shall be measured in accordance with
method 1013 of FED-STD-228, except for tape wrapped jacket constructions. For tape wrapped jacket
constructions, use method 1018 of FED-STD-228.
4.6.12 Flammability. Finished cable shall be tested in accordance with ASTM D3032. The period of
flame application shall be 30 seconds for cables having wires of size 10 AWG or smaller. Cables with
larger wires than 10 AWG shall not be tested.
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