Electrical Cable Assemblies
Modern power cables come in a variety of sizes, materials, and types, each particularly adapted to its uses. Large single insulated conductors are also sometimes called power cables in the trade.
Cables consist of three major components — conductors, insulations, and protection. The constructional detail of individual cables will vary according to their application.
Cable construction and material are determined by four main factors:
- Working voltage, which determines the thickness and composition of the insulation
- Current carrying capacity, which determines the cross-section size of the conductors
- Environmental conditions such as temperature, chemical or sunlight exposure
- Mechanical impact, which determines the form and composition of the cable jacket enclosing conductors
Since power cables must be flexible, copper or aluminum conductors are made of stranded wire, although very small cables may use solid conductors. The cable may include un-insulated conductors used for the circuit neutral or for ground (earth) connection. Where applications require a cable to be moved repeatedly, more flexible cables are used. Small cables are called "cords" (North American usage) or "flex" (United Kingdom). Flexible cords contain finer stranded conductors, rather than solid, and have insulation and sheaths that are engineered to withstand the forces of repeated flexing. Heavy duty flexible power cords such as feeding a mine face cutting machine are carefully engineered -- since their life is measurable in weeks. Very flexible power cables are used in automated machinery, robotics, and machine tools.
Types of Flexible Power Cables