Design and Development of Back-to-Back Gas-to-Cable Termination for 420 kV Gas Insulated Switchgear

Gas-to-cable termination module is an important terminal equipment of Gas Insulated Switchgear (GIS). This module acts as an interconnection between metal enclosed gas insulated switchgear and cross-linked polyethylene (XLPE) cable. Basically it facilitates the transition of high voltage connection from SF₆ gas environment to HT conductor of XLPE cable. Even though gas-to-cable termination is an optional item/module, most of the gas insulated switchgear configurations require gas-to-cable terminations instead of gas-to-air bushings to extend high voltage connection from GIS to yard equipment. Compact cable terminating systems, consisting of pre-fabricated and tested components, with their short assembly times, help in a reliable integration at the high voltage level. In the present contribution, back-to-back gas-to-cable terminations with XLPE cable link of about 4–5 meters has been designed, developed and evaluated for 420 kV gas insulated switchgear applications. Dimensions of gas-to-cable termination housing, necessary high voltage (HV) adapters for integration to GIS, mounting arrangement etc. are designed based on recommendations provided by IEC 62271-209. The developed system is further helpful for site testing of GIS through gas filled test transformer. The developed prototype of gas-to-cable termination module has been successfully evaluated for routine test duties such as power frequency withstand voltage and partial discharge measurements according to IEC 62067, IEC 62271-203 and IEC 62271-209.