Cable Insulation not only prevents current leakages from the wire that can lead to disastrous consequences but also protects the cable from weather elements, oils, chemical solvents, cuts, abrasions thereby increasing its working life.

In a single voltage rating, three insulation levels are used; 100%, 133% and 173% . These insulation levels are based on the speed at which the protective relay is designed to de-energize the system. The following table details the classification:

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Insulation thickness absorbs voltage stresses for a given time. Consequently, the higher the voltage capacity of a cable more thickness will be required. For Low Voltage Cables, from 0 to 2000V , the voltage stresses are negligible and usually these cables are over-insulated from voltage stress view-point, however for High Voltage cables, these stresses are huge and therefore insulation thickness becomes more important. An industry wide standard is followed for Specific Insulation Thickness for voltage ratings upto 46kV. Below is table listing these values.

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