Considerations on the effect of a temperature gradient on the dielectric performance of a CGI bus

When a compressed-gas-insulated (CGI) bus section is subjected to a temperature gradient, the gas molecules tend to concentrate in the cold portion of the bus, creating a local reduction in the gas density in the warm portion, and thus affecting the dielectric strength of the overall bus, The effect is even greater when the outdoor temperature reaches the point of gas liquefaction: a) it causes the gas liquefaction in the cold portion to occur at a slightly higher temperature; b) it intensifies the reduction of the gas density in the warm portion with a corresponding deterioration of the dielectric strength of the bus.