Super compact RBJ (rubber block joint) with high dielectric constant layer

Application of rubber block joint (RBJ or one piece joint) has been recently increasing for a 66 kV or more XLPE cable from the merit of easy construction. We have developed the more economical and super compact RBJ whose volume is reduced to about 1/3 of the conventional one, by employing the high dielectric constant (ε) thin layer between insulation and inner semi-conductive electrode layer in order to relieve electrical stress. The high ε rubber containing much amount of high ε filler is key material of this joint and the most important factor of high ε rubber is to prevent the fall of mechanical and electrical properties such as electrical breakdown strength and dielectric loss. This report describes the characteristics of high ε rubber and super compact RBJ applying this high ε rubber.