Controlled Switching of Power Transformer and Shunt Reactors for Minimization of Switching Transients: A Review

Switching transients arises due to random switching of power apparatus results in degradation of thermal and dielectric health of equipment and system as a whole. Controlled switching or point on wave control has emerged as excellent solution for minimizing the charging transients and can aid the better condition monitoring of circuit breaker. Different switching strategies are in place based on different design and connection configurations. Each methodology has certain advantages and dis-advantages. The performance of control switching is dependent on the dielectric performance of insulating medium and circuit breaker performance. The effect of variations in insulation dielectric properties and breaker mechanical performance has been discussed in depth in this paper. Selection and performance of feedbacks used in controlled switching also play a major role in target evaluation and needs proper assessment. Review of different controlled switching methodologies in respect of transformer and shunt reactor have been discussed in paper augmented with field cases. Based on the review of available controlled switching methodologies and field experience, the acceptance criteria have been proposed.