Patent ID: 6493203
Filing Date: 2002-12-10
Classification: H01H,H02H

Abstract:
A phase control switch apparatus, comprising:a breaker connected to a reactive load which is connected to a three-phase electric power system in &Dgr;-connection or alternatively in Y-connection with a neutral point connected directly to the ground or alternatively not connected to the ground, said breaker being designed to break a fault current and a load current flowing through said reactive load or make said reactive load closed to said three-phase electric power system for excitation thereof, voltage measuring means for measuring phase voltages on a phase-by-phase basis; current measuring means for measuring inter-contact currents at an output side of said breaker; actuating means for effectuating open/close operations of contacts of said breaker independently on a phase-by-phase basis; temperature measuring means disposed in the vicinity of said actuating means; reference phase detecting means for detecting driving pressures and control voltages of said actuating means for said breaker on a phase-by-phase basis, said reference phase detecting means being so designed as to respond to a brake/make command issued to said breaker to thereby predict waveforms of phase voltages, respectively, upon closing of said breaker as well as phases and periodical zero points of waveforms of phase currents, respectively, upon opening of said breaker on the basis of voltage values and current values measured by said voltage measuring means and said current measuring means, respectively; residual magnetic flux predicting means for storing breaking time points of the phase contacts of said breaker, respectively, and positive/negative polarities of individual phase currents immediately before breaking in a preceding breaking operation to thereby predict residual magnetic fluxes in the individual phases of said reactive load on the basis of the contents as stored; optimal closing time point predicting means for predicting upon closing of individual phase contacts of said breaker an optimal closing electrical angle for each of the phases on the basis of the residual magnetic fluxes of said reactive load in the individual phases as predicted by said residual magnetic flux predicting means so that surges occurring upon closing of said breaker contacts can be suppressed each to a minimum; and contact closing operation starting means for validating contact closing operations of said breaker so that said phase contacts of said breaker can be closed at the electrical angles, respectively, which are predicted and set by said optimal closing time point predicting means.