Theoretical and Experimental Investigations on Circuit Breaker Transient Recovery Voltages

Abstract

The purpose of this paper is to present the results of theoretical and experimental investigations conducted on the kilometric faults inpower networks and their impact on the electromagnetic transient recovery voltages in the circuit breaker (CB). In the analytical study, an accurate Laplace s-domain distributed parameter analysis used to obtain A,B,C and D constants of two transmission systems before and after CB. Having the input impedances of two line sections derived from network constants and the laplace transform of the interrupted fault current, simulated by injection of a current ramp time function, an s-domain expression for voltage across C.B. is obtained and laplace-inverted using a numerical technique to obtain its corresponding time waveform. In an expeimental study, a Transient Network Analyzer (TNA) was used for simulating two line sections and Current Injection Unit (CIU). Circuit breaker recovery voltage could then be observed and photographed using a cathode ray oscilloscope and a suitable camera. Different fault and breaker locations could be simulated on TNA by changing the place of the CIU. A comparison showing the agreement between analytical and experimental studies will be presented and several case studies will be reported.