Shield-Interrupt Overvoltages On 138-KV Extruded Dielectric Cables

Special shield-bonding techniques have been used on underground transmission cables to minimize the circulating currents in the shields which, in turn, reduce the loss and heating effects. The techniques used on extruded dielectric cables can result in a very economical cable installation. However, the shield interrupts, where the special bonding takes place, have been a source of problems to the industry because these shields have been subjected to excessive overvoltages. This work defines the overvoltages that may be seen at shield interrupts on 138-kV extruded dielectric cable systems over a wide range of system conditions.