Present Status of the Corona- and Heat-Resistant Cable Insulation Based on Ethylene-Propylene Rubber

The data presented in 1962 and 1963 on a new corona- and heat-resistant cable insulation1 based on ethylene-propylene rubber are augmented by data on the long-term stability of the insulation in water at various temperatures and additional data on resistance to corona and stability in long-term load-cycling test at high temperature and voltage. Experience with 4 000 000 conductor feet of cables rated for service from 5 to 35 kV with conductors up to 750 kcmil has been trouble-free since their installation in 1964, 1965, and 1966. The two prototype cables installed in 1962 are also operating perfectly. The suitability of this insulation in 3/C compact sector conductor cables has now been demonstrated. The advantages of insulations of this type for medium-high-voltage power cables is becoming evident throughout the world. A specification for a corona- and heat-resistant cable insulation is proposed.