Design, development and testing of low scatter mechanical drives for point-on-wave switching in 400 kV AIS circuit breakers

Safe & reliable power system is established by suppressing or limiting the system over-voltages & transients. Major sources of these types of transients in Power system is switching operations of Circuit breakers on different loads such as Long lines, Transformer loads, Capacitive banks etc., At present major manufacturers use Pre-Insertion Resistors (PIRs) to suppress over-voltages to avoid wear & tear to Circuit breaker and extending life of CBs. Now, major utilities and OEMs are moving towards CS devices to use accurate point-on-wave switching to suppress these over-voltages. It is an intelligent relay which predicts and instructs to delay the switching time according to the circuit parameters such as load type, voltage & current on both ends of Circuit breaker. However, this necessitates a high precision or low scatter mechanical drive which can achieve this accurate timing required. This is also insisted that we test our Circuit Breakers for low scatter performance as per IEC-62271-302. In this paper we elaborate the design, development and testing of low-scatter drive for 400 kV Circuit breaker