Optimal Conditions for Controlled Switching of a Three-Phase Shunt Reactor

Abstract

The switching of shunt reactors in an electrical network is in many cases accompanied by reignition of the arc in the circuit breaker and the occurrence of dangerous overvoltage in the network. To limit such overvoltage, controlled-switching devices are used to switch off the reactor in the optimal phase of the current. To select the optimal switching conditions, the switching processes are analyzed, taking into account the intuitively clear difference between the switching conditions for three-phase and single-phase shunt reactors due to the electrical and/or magnetic coupling between the phase windings. The proposed method of analysis is universal for all types of three-phase shunt reactors due to the use of a universal four-legged star equivalent circuit. The reactor phases are switched off, synchronized against the phase Avoltage curve, in the sequence A → C → B to minimize the total switching time.