Seismic Performance of High Voltage Composite Insulator Circuit Breaker

Dynamic seismic force causes damage to electrical equipment and structures resulting in loss of human and animal life. High voltage substation equipment are highly vulnerable to earthquake event compared to low voltage distribution network. Vulnerability to seismic event increases with increase in voltage rating of substation due to taller and slender porcelain structures. Porcelain insulators used in substation equipment have high compressive strength but weak tensile strength. Hence ceramic insulators are the weakest part in the substation equipment in the event of earthquake. Earthquake with 0.1g zero period acceleration can cause massive damage to high voltage substation equipment. Substation equipment with composite insulator are comparatively less vulnerable to seismic loading. Central Power Research Institute (CPRI) is equipped with state-of-the-art tri-axial shake table facility for simulating tri-axial earthquake vibration. Seismic qualification methods, codal provisions and seismic performance of 145 kV three pole operated composite insulator SF6 circuit breaker by shake table method are discussed in this paper. The seismic strain at critical locations, response acceleration on circuit breaker are presented along with relative displacement at the terminal of circuit breaker.