External Flashover of Generator Circuit Breaker in Coastal Power Plants having Air Insulated Switchyard

Abstract

The breaker flashover can be either internal or external. External flashover is mainly due to deposition on the external surface of the contact housings. In case of Power Stations in coastal areas, salt deposition takes place because of saline atmospheric pollution. Breaker flashover is an abnormal condition and may result in severe damage to capital equipment like Generator and Generator Transformer. Additionally it may also result in explosion of Circuit Breakers which can damage nearby equipment in Switchyard and put Substation personnel at risk. Numerical relays used for Generator Protection have the feature to detect breaker flashover condition and quickly isolate the equipment. This paper describes such problems at Mundra Thermal Power Plant in western coast of India and also dwells upon the causes, protection philosophy, preventive measures and recommendations. 