sy cable

An SY control cable is a flexible instrumentation electrical cable designed for measuring, control or regulation in the field of process automation. It is a flexible multicore cable, with (class 5) copper conductors and a galvanised steel wire braid (GSWB) for mechanical protection. The cable is typically manufactured with PVC insulation, bedding and a transparent PVC sheath. The transparent sheath means signs of deterioration, damage or corrosion can be detected with ease.
SY has a voltage rating of 300/500V.
SY cable should not be used on voltages above ELV in the UK as the braid does not meet BS 7671 for current carrying capacity under fault conditions.
Only cables mentioned in BS 7671 should be used unless the designer can show that the cable used meets the same standards. Although the combined cross sectional area of the braid may meet the adiabatic equation requirements for earthing, the nature of the braid being made of very fine strands coupled with the comparatively large gaps, when compared to SWA cable, means that under short circuit conditions the fine strands can melt and so the braid will no longer be in contact with a penetrating object such as a screw or nail
Some SY cables on the market are of poor standard, with cases of GSWB coverage being less than 20%. With no standard set, poor quality cables are available on the market at low procurement costs - but this cable's life will be substantially lower. A GSWB coverage of above 55% attains to acceptable standard SY.

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