MIL-DTL-24640/18 3XSW and 3XSOW Shipboard Cable

Mil-Spec Military part number MIL-DTL-24640/18 has two cable-type designations: 3XSW and 3XSOW. The cable is rated for 600 volts and uses Standard Identification Code by Method 2.  24640/18 cords use Extruded irradiated cross-linked Polyalkene insulation with irradiated cross-linked Polyvinylidene Fluoride (PVDF) insulation and have a low-smoke zero-halogen (LSZH) cross-linked polyolefin (XLPO) jacket. The cable contains multiple conductors, with three component wires, black, white, and red twisted together to form a triad. The two conductors are insulated as discussed above and tested in accordance with SAE-AS81044/12 except that the identification will be according to MIL-STD-24640. Each pair can then have an optional binder tape, followed by a braided shield of 38 AWG tin-coated copper braid. Additional shield insulation of two polyester tapes or a single polyester tape with an extruded jacket is added.

 

The required number of shielded triads are cabled together with an optional binder tape and are sequenced with number 1 in the center outward. 3XSW is then jacketed with a low-smoke, zero-halogen (LSZH) cross-linked polyolefin (XLPO) jacket. 3XSOW enshrouds the assembly in a shield composed of a tin-coated copper braid before applying the XLPO jacket. Fillers may be used to make a round cable. These cords are lightweight, watertight, and have non-flexing service. These cables operate within a temperature range of -20°C to +105°C. Watertight cables can operate in a wide variety of situations, including through bulkheads and between decks.

What does the cable designation 3XSW mean?

In the cable designation for 3XSW, 3 refers to the fact that three conductors are twisted into triads, X refers to irradiated cross-linked Polyalkene insulation with irradiated cross-linked Polyvinylidene Fluoride (PVDF) insulation, S refers to individual shielding in 38 AWG copper braid shield of each pair, and W refers to the watertight nature of the cable.

What does the cable designation 3XSOW mean?

In the cable designation for 3XSOW, 3 refers to the fact that three conductors are twisted into triads, X refers to irradiated cross-linked Polyalkene insulation with irradiated cross-linked Polyvinylidene Fluoride (PVDF) insulation, S refers to individual shielding in 38 AWG copper braid shield of each pair, O indicates that the cable has an overall optimized tin-coated copper braid shield, and W refers to the watertight nature of the cable.

M24640/18 Construction:

• Conductors: 7-strand tin-coated copper conductors
• Insulation: Extruded irradiated cross-linked Polyalkene insulation with irradiated cross-linked Polyvinylidene Fluoride (PVDF) insulation
• Shielding:
  • Each pair of conductors features an overall tin-coated copper braid shield
  • For 3XSOW, there is an additional overall optimized tin-coated copper braid shield
• Jacket: Low-smoke zero-halogen (LSZH) cross-linked polyolefin (XLPO).

M24640/18 Ratings and Approvals

• Mil-Spec: MIL-DTL-24640
• Navy Shipboard Spec:
  • 3XSW for shielded pairs
  • 3XSOW for shielded pairs with an overall braid shield
• SAE-AS81044/12 except that the identification will be according to MIL-STD-24640
• Voltage Rating: 600V

Features and Benefits of M24640/18 Cords

• Watertight cables can operate in a wide variety of situations, including through bulkheads and between decks.
• Cross-linked polyalkene/polyvinylidene fluoride insulation provides protection in environments with ultra-high vacuum, high temperatures, and ionizing radiation.
• LSZH jacket is fire resistant and emits low smoke, which is ideal for shipboard settings which often have restricted ventilation
• LSZH jackets also emit low acid, gas, and toxicity when subjected to fire, maintaining circuit integrity
• Shielded cables reduce electrical noise created by electromagnetic signals in the cable while also providing greater protection and durability than unshielded cables.
• Braided shielding is heavier than foil shielding and provides additional protection against EMI/RFI as well as protecting the cable in rugged environments. The braided shield also provides better grounding than foil shields.