Critical Analysis of IS 1255-1983, Reaffirmed 1996 for “Code of Practice for Installation and Maintenance of Power Cables up to and Including 33 kV Rating”

Abstract

Traditionally power cables, during installation or maintenance, are tested with a dc high voltage for its electrical strength as prescribed in IS 1255-1983, reaffirmed 1996. Modern extruded dielectric power cables such as Cross Linked Poly Ethylene (XLPE) have inherent space charge accumulation tendencies when subjected to a high voltage dc. The accumulated space charge leads to over stressing of insulation resulting in cable breakdown with a high downtime and repair costs. As IS 1255-1983 is silent on the harmful effect of dc on XLPE cables, power companies in India are facing revenue losses as well as the quality of service to the consumer is affected.This paper analyses the demerits of IS 1255 and compares it with the other available test methods such as Very Low Frequency (VLF) and Damped Alternating Current (DAC) test, as well as condition assessment methods, such as Dissipation Factor and Partial Discharge. A case study highlighting the advantages of newer test methods has been presented and a cost to benefit analysis is undertaken.