The choice of cable type for application at EHV system voltage

The choice of underground cable type for EHV applications has increased as a range of new dielectrics has been developed. The authors consider the three types of single core cable now available for high power applications at system voltages of 220 kV and above: oil filled, paper insulated cable; oil filled, polypropylene/paper laminate insulated cable; and solid, polymeric insulated cable. Consideration is given to key aspects of EHV cable design and the choice of manufacturing plant required to achieve the necessary insulation quality. These aspects include features common to each type of cable, such as the need for large conductors, high insulation design stresses and metallic sheaths. A performance comparison is made between the three cable types based upon their current ratings.