Health index and risk assessment models for Gas Insulated Switchgear (GIS) operating under tropical conditions

This article contains the development of the Health Index (HI) and the Risk Assessment (RA) models for Gas Insulated Switchgear (GIS) operating under tropical conditions. A case study of 631 bays of GIS in tropics with service time from 1 up to 30 years is used during the development of the models. The basis for the HI model is the condition assessment of subsystems in GIS. This assessment translates the measured parameters from GIS subsystems into condition status based on a set of norms and rules. The condition status is presented in a score, where the non-linear scaling is chosen as it allows the poor parameters to really stand out. On the other hand, the RA model calculates the risk of a GIS major failure. The Total Failure Probability (TPF) unifies six risk indicators of GIS failures under tropical conditions. The risk may fall into one of the four categories, namely: Low, Medium, High, and Very High.