Non intrusive method for the assessment of SF/sub 6//N/sub 2/ gas mixture ratio

The quest for the proper mix ratio with time in SF/sub 6//N/sub 2/ gas circuit breakers has always been a problem. This paper brings a solution by tackling the gas mix thermodynamic state equations. We present here the study made on the pressure, temperature, density and gas mixture ratio. The knowledge of the phenomena is associated with the determination of the first three of the four variables listed above, a set of four equations and the solution for the gas mix ratio. The selection of the sensors is described. The main advantage is that it is a non-intrusive method and can be performed online with sensors and electronic instrumentation of today's technology.