Influence of an insulating spacer on the V-t characteristics of a coaxial gas-insulated cable. I. Study on a reduced-scale coaxial conductor

Two different spacer designs, a disc spacer and a composite-profile cone, were evaluated in a coaxial conductor 2.5/7 cm in diameter to study their influence on the V-t characteristic of the conductor when it is subjected to repeated applications of impulse voltages of constant waveshape and increasing magnitude. The results show that an insulating spacer can reduce the critical withstand voltage and yield smaller dispersion in the breakdown voltages. These effects can be minimized by adopting a design that favors breakdown in the gas rather than along the spacer interface