Effect and physical behaviour of carbon-black papers used as a conductor screen

Conductor screens are now in general use on high-voltage power cables. They take several forms, and are especially effective in bringing about an improvement in a.c. electric strength. Good-quality cable paper loaded with a carbon-black material is one form used for conductor-screening purposes, but it can have adverse effects when applied to oil-filled cables. These include an increase in the ionisation factor and a decrease in the impulse electric strength. The paper records the result of comprehensive investigation into many aspects of carbon-black-paper screening, and claims conclusively to establish the behaviour of carbon loading when used in paper for screening purposes.