An experimental and numerical study to evaluate performance parameters of GIS circuit breaker during low current interruption

Abstract

Abstract The basic philosophy of two-stage blast interrupter is combination of self-blast and puffer-interrupter principles. Gas circuit breaker (GCB) with two-stage blast interrupter has two gas chambers. High gas pressure in one chamber generates by using arc energy and in other chamber, by mechanical compression. In such type of breakers, interruption becomes quite difficult at low currents and hence optimization of gas chambers design is essential. In view of above, a numerical program has been developed to calculate SF6 gas pressure-rise in various interrupter volumes and gas flow rates across different passages of interrupter w.r.t. time. To validate model developed in the study, an experimental set-up is established and measured transient gas pressure-rise generated during 420 kV GCB operation. The effect of speed-time characteristics, stroke length and piston diameter on performance parameters of 420 kV GCB model is analyzed. Further, to understand gas flow pattern across insulated nozzle during GCB operation, authors developed a CFX model. By using this numerical model, effect of nozzle profile, gas flow passage areas and profile of gas discharge vents on transient gas pressure and Mach number distribution across inter-electrode gap and gas flow rates through various outlets has been discussed in detail in the paper.