Connectivity Guide

Insulation

The smooth, non-conductive covering extruded over a bare metal conductor is called insulation. It is meant to support and separate conductors while insulating them from electrical leakage. If it were not for insulation, wires could not be grouped together to form a cable without shorting out. While bare conductors have real world practicality, they pale in comparison to the amount of application usages for insulated wire. The most commonly used insulating materials are:

• Thermoplastics: PVC, PE, PP, PTFE • Elastomers (rubber): CR, SR • Thermoplastic elastomers: PUR, TPE-E

Wire identification

To connect the wires correctly, they must be accurately identified. For this purpose, wires are either numbered or color-coded according to electrical standards. Unless otherwise noted, all power and control cables include a green/yellow ground wire.

Cabling

The method where individual wires are twisted together to form a smooth and even, round cable core configuration is known as cabling. Cabling is used whether the conductor layout consists of same-sized conductors or composite cable designs with different components in addition to single conductors, such as coaxial or thermocouple cables. Cabling is required for pairs, triads, or quad designs where 2 or more single conductors are twisted together into a circular formation. Depending upon the number of wires used, the cabled core can consist of several layers on top of one another to accommodate design requirements. There are several cabling techniques that can be employed depending on the end-use application requirements:

• Unilay / bunch: Conductors are twisted together with the same lay direction and cable lay length. Typical of stationary cable designs. • Concentric contra-helical: Conductors are surrounded by well-defined layers in reversing direction and increasing lay length. Typical for continuous flexing cable. • Concentric unilay: Conductors are surrounded by layers with the same lay direction and increasing lay length in each succeeding layer. Typical for torsion and continuous flexing cable.

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Archived copy. For current information see: www.lappusa.com