1、 INCH-POUND MIL-DTL-24643/38F 1 October 2009 SUPERSEDING MIL-DTL-24643/38E 22 August 2002 DETAIL SPECIFICATION SHEET CABLE, ELECTRICAL, -20 C TO +90 C, 600 VOLTS, TYPE LSECM This specification is approved for use by all Departments and Agencies of the Department of Defense. The requirements for acqu
2、iring the product described herein shall consist of this specification sheet and MIL-DTL-24643. Construction, Watertight Component 1: 8 shielded pairs First - Copper conductor, tin-coated, in accordance with ASTM B286, 20 AWG 7 strands. Second - Separator may be used at manufacturers option where re
3、quired to provide free-stripping insulation. Third - Thermoset insulation. Nominal wall thickness of 0.023 inch; wall thickness may vary from nominal as necessary, in order for the completed cable to meet the specified electrical requirements. Colored insulation, one white and one black conductor fo
4、r each pair. Fourth - Two conductors (one black and one white) cabled together with a nominal lay of 2.5 inches to form a pair. Fifth - An optional binder. Sixth - Braided shield of 34 or 36 AWG, tin-coated copper. Braid angle of 20 to 40 degrees; minimum coverage of 85 percent. Seventh - Shield ins
5、ulation of two polyester tapes, outer tape sealed. An alternate shield insulation may consist of one polyester tape, plus an extruded jacket of a suitable transparent material, minimum average thickness of the transparent material 0.003 inch. The standard identification code shall be applied by Meth
6、od 2. Component 2: 8 group (seven conductors in each) First - Copper conductor, coated or uncoated, 18 AWG, Class B stranding (7 by 0.0152 inches). Maximum diameter of 0.050 inch. Second - Thermoset insulation. Nominal wall thickness of 0.008 inch. Colored insulation, five black and two white conduc
7、tors for each group. Third - Seven conductors, five black and two white, with the white conductors adjacent in the layer of six, cabled with a lay not greater than 2 inches, to form each group. AMSC N/A FSC 6145 Provided by IHSNot for ResaleNo reproduction or networking permitted without license fro
8、m IHS-,-,-MIL-DTL-24643/38F Fourth - Group covering of two polyester tapes, outer tape sealed. An alternate shield insulation may consist of one polyester tape, plus an extruded jacket of a suitable transparent material, minimum average thickness of the transparent material 0.003 inch. The standard
9、identification code shall be applied by Method 2. Assembly First - Five pairs cabled to form a core. Three pairs and eight groups of seven cabled over the core, with a lay in accordance with 3.4.4 of MIL-DTL-24643. Pair no. 1 through 5 in core; the sequence of the outer layer pair no. 6; groups no.
10、1, 2 and 3: pair no. 7: groups no. 4, 5 and 6: pair no. 8: groups no. 7 and 8. Fillers may be used as necessary to form a firm, well-rounded assembly. Second - An optional binder. Third - Cross-linked polyolefin jacket (see table I for jacket thickness). TABLE I. Details. Overall diameter Military p
11、art no. M24643/38 Type Number of pairs / number of conductors Cable jacket thickness min. avg. (inch) min. (inch) max. (inch) -01UN LSECM 8/56 0.075 1.290 1.370 REQUIREMENTS: Qualification required. INSPECTION: Basic Electricals: Conductor resistance (ohms/1000 feet at 25 C, max.) ASTM B286, Size 20
12、7 11.03 18 AWG, Class B 7.47 Voltage withstand (volts, root mean square, min.) Conductor to conductor 2000 Conductor to shield (pairs only) 1000 Component shield to component shield 500 Insulation resistance (megohms/1000 feet, min.) Conductor to conductor 500 Conductor to shield (pairs only) 500 C
13、omponent shield to component shield 100 Conductor continuity No failure Shield continuity No failure 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-24643/38F Group A: Visual and dimensional No failure Watertightness (see MIL-DTL-24643 for
14、limits of water leakage) No failure Capacitance (pairs only) Mutual capacitance, 1 kilohertz (KHz) (pF/ft, max.) 30 Group B: Thermoset proof test (percent, max.) Insulation 50 Jacket (when tested at 200 C) 50 Physicals (unaged) Insulation (extruded) Tensile strength (lb/in2, min.) 700 Elongation (pe
15、rcent, min.) 150 Jacket (cable) Tensile strength (lb/in2, min.) 1300 Elongation (percent, min.) 160 Tear (lb/in thickness, min.) 35 Drip (951 C) Zero Group C: Physicals (aged) air oven Insulation (extruded) Tensile strength (percent of unaged, min.) 75 Elongation (percent of unaged, min.) 75 Jacket
16、cable) Tensile strength (percent of unaged, min.) 60 Elongation (percent of unaged, min.) 60 Permanence of printing (jacket) (cycles, min.) 125 Heat distortion (percent of unaged, max.) 30 Shrinkage No failure Cable sealant removability No failure Shield (conformance to material, construction and c
17、overage) No failure Group D: Flame propagation (cable) No failure 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-24643/38F Qualification Inspection: Qualification inspection shall include basic electricals; groups A, B, C, and D; plus the
18、following: Aging and compatibility (cable) (1255 C) No failure Abrasion resistance (jacket) (scrapes, min.) 75 Acid gas equivalent (percent, max.) Jacket 2 Fillers 2 Insulation 18Shield insulation /group covering 2 Halogen content (percent, max.) Jacket 0.2 Fillers 0.2Insulation 0.2Immersion (jacket
19、) Tensile strength (percent of unaged, min.) 50 Elongation (percent of unaged, min.) 50 Smoke index (max.) Jacket 25 Fillers 45Insulation 45 Toxicity index (max.) Jacket 5 Fillers 5Insulation 1.5Durometer (jacket) - Type A (hardness, min.) 80 Weathering (jacket) No failure Electrical moisture absorp
20、tion No failure UNIT ORDERING LENGTHS: Type Feet (nominal) LSECM 1000 CHANGES FROM PREVIOUS ISSUE: Marginal notations are not used in this revision to identify changes with respect to the previous issue due to the extent of the changes. 4 Provided by IHSNot for ResaleNo reproduction or networking pe
21、rmitted without license from IHS-,-,-MIL-DTL-24643/38F 5 Custodians: Preparing Activity: Army MI Navy SH Navy SH (Project 6145-2008-042) Review Activities: Army AR, AV, CR Navy CG, EC DLA CC NOTE: The activities listed above were interested in this document as of the date of this document. Since organizations and responsibilities can change, you should verify the currency of the information above using the ASSIST Online database at http:/assist.daps.dla.mil. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
