110 / 2021-06-09 15:55:35

STUDY ON DESIGN OPTIMIZATION OF THE NOZZLE INTERRUPTER IN GAS BLAST CIRCUIT BREAKERS

The supersonic nozzle interrupter is the key component determining the arc interruption capability of gas blast circuit breakers. The present study performs a computational study on the effects of nozzle geometry, including a few key parameters and the size, on the thermal interruption capability of a circuit breaker. The study of based on the model circuit breakers and arcing conditions used in the experimental study of General Electric Company, which reports measurements of thermal interruption capability (characterized by critical rate of rise of recovery voltage, RRRV) with SF₆ as arc quenching medium, and using nozzles having differences in upstream section, throat section and downstream expansion angle, etc., as well as affinely related nozzles at different sizes.



Computational results will be compared with corresponding measurement to verify the arc model. A detailed analysis will be carried out to study the influences of nozzle parameters, i.e. upstream contraction angle, throat length and downstream expansion angle on dominate arc cooling mechanisms, thus thermal interruption capability, specially during current zero period. An attempt will also be made to find possibly the scaling laws of nozzle interrupters in gas blast circuit breakers. The findings from this study can be valuable in optimum design of gas blast circuit breakers.