${\rm CO}_{2}$ as an Arc Interruption Medium in Gas Circuit Breakers

${\rm CO}_{2}$ is a possible alternative to ${\rm SF}_{6}$ —which has a high global warming potential—as the interruption medium in gas circuit breakers. The performance of ${\rm CO}_{2}$ is investigated in this paper by carrying out experiments in representative test devices and by performing computational fluid dynamic (CFD) simulations; some comparisons with ${\rm SF}_{6}$ and air are given. It is found that the thermal interruption performance of ${\rm CO}_{2}$ is lower than that of ${\rm SF}_{6}$ , but higher than that of air. The measured dielectric recovery after arcing is compared for ${\rm CO}_{2}$ and ${\rm SF}_{6}$ ; a streamer model is used to calculate the breakdown voltage in ${\rm CO}_{2}$ ; good agreement with measurement is found. The speed of sound and the adiabatic coefficient, important parameters that influence pressure buildup and gas flow, are compared for ${\rm SF}_{6}$ , ${\rm CO}_{2}$ , and air. CFD simulations of the pressure buildup in ${\rm CO}_{2}$ and ${\rm SF}_{6}$ both illustrate the qualitative differences between the two and show good agreement with measurements.