MIL-DTL-28781E
S
C2S
C1S
2
1
CSg
C2g
C1g
DIFFERENTIAL
CAPACITOR
FIGURE 3. Test method for determining capacitance unbalance of pair-to-shield.
S indicates all wires (except conductors 1 and 2) bunched together. If a group or subgroup is always
separated from the shield (by other groups or subgroups) the wires of a pair in the separated group have
very small direct capacitances to the shield and their difference is negligible.
4.6.4 Cold bend test. The cold bend test for the insulation material and jacket material shall be
4.6.4.1 Specimens. For cables with an overall diameter of less than .5 inch (12.70 millimeters), the
test specified in 4.6.4.2 shall be conducted on three specimens of cable; the length of each specimen
shall be at least 150 times the diameter. For cable of .5 inch (12.70 millimeters) and greater nominal
diameter, the test specified in 4.6.4.2 shall be conducted on two specimens of cable. The length of each
specimen shall be at least 120 times the diameter of the cable.
4.6.4.2 Procedure. One end of the test specimen shall be clamped circumferentially at two points,
approximately 45 degrees apart, to a mandrel whose diameter is 10 times that of the test specimen. The
specimen shall then be conditioned for 20 hours at -40±4 °F (-40±2 șC) except for cable .250 inch
(6.35 mm) overall nominal diameter and smaller, which shall be conditioned for 20 hours at -58±4 °F
(-50±2 șC). During this conditioning period, the specimens shall be kept reasonably straight. After this
conditioning, but while the specimens are still in the cold chamber at the conditioning temperature, the
specimens shall be wrapped for three close turns (two close turns for cables having a diameter .5 inch
(12.70 mm) and greater) around the mandrel. This shall be done at a uniform rate of 15±3 revolutions per
minute, preferably by means of an electrically driven motor. The cable shall be guided by a free moving
sheave or transversing device, in intimate contact with the cable at the initial point of bend. The cable
shall be removed from the cold chamber and shall satisfactorily meet the dielectric withstanding voltage
requirement of 3.2.4.1. The cable shall be visually examined for evidence of cracks or flaws in the
insulation material or jacket.
4.6.5 Tensile strength and elongation test. Samples of the conductor insulation or the jacket
material, removed from the finished cable or conductor, shall be tested in accordance with standard
ASTM-D470 for the conductor insulation and jacket. The tensile strength of the cable jacket shall be
15
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business