A common challenge facing today's cable/system designers is selecting the correct combinations of signal, power, and control cables that meet unique system requirements whilst working within the space budget available and satisfying the specification requirements imposed by the industry served.
The need to be subservient to these specifications will typically drive the designer into choosing from a limiting catalogue of parts listed in the applicable specifications. Typically, as a result, multiple cable constructions will be chosen in combination in order to meet the total system requirements.
The use of multicore / hybrid cables often significantly reduces the weight and volume that the cabling occupies. These savings, in turn, lead to easier installation, clamping, and maintenance of the cable in the available space, while providing greater choice in routings and system functionality.
One additional trend driving interest in multicore cables is its close association with advanced material science that yields thin-wall insulations and jackets. These products can reduce cable diameters in the range of 30% to 40%, whilst maintaining the mechanical toughness, electrical characteristics and environmental performance of these products when compared to standard-wall cables. The smaller size is often accompanied by reduced weight and improved system functionality.
Choosing the correct cable for the environment to ensure the correct fit, form, and function is essential. Parameters such as temperature rating, fluid resistance, mechanical strength, ease of use, and installation all need to be considered carefully. Cable failure normally leads to systems failure, which can be catastrophic.
The primary role of the specification has to be to ensure the correct use of products that satisfy the needs of the application and also exclude products that would be unsuitable.
Specifications should clearly define the attributes of the cables in key performance areas, but today’s reality is that the approach to achieving this is often feature driven. Such that, the cable is defined by such parameters as wire gauge, materials, stranding, and insulation material/thickness.
In essence, military wire and cable specifications say, “If you build the cable my way, it will be suitable for your application.” Another approach is to say, “If the cable has these performance attributes, it will be suitable for your application.” The difference in the two approaches is subtle but critical.
In summary, multicore/hybrid cables are often custom or semi-custom in construction and offer many advantages; but appear to be something that the military wire and cable specifications world seems to be uncomfortable with.
By John Wadeley