Epoxy Resin-Orlon Cable Terminations for 33-Kv Service

Design of a termination for 33-kv operation has been described. This includes a wrapping of insulation comprising orlon tape impregnated with an epoxy resin formulation that extends over a portion of the metallic cable sheath, the oiled-paper, insulation, and a portion of the high-voltage connector. The prepared cable end is installed in a porcelain pothead which is almost completely filled with cable oil. Passage of oil between the pothead and the cable is prevented by the resin insulation. Savings are effected over standard oilfilled pothead construction in that oil reservoirs are not required, nor is periodic inspection and maintenance of oil level. Previous semisolid filled terminations required construction and filling in the shop. Additional splices were then required in the field to connect the pothead to the cable. The present termination is made in the field making additional splicing unnecessary. Temperature-cycled overvoltage tests and impulse voltage tests support the expectation of long life and adequate impulse strength level. Other test results including breakdown voltage strength, dissipation factor, dielectric constant, resistance to moisture, and adherence to metals indicate that satisfactory performance may be expected. The use of epoxy-resin-impregnated orlon terminations is now standard practice in the Baltimore Gas and Electric Company's 33-kv transmission and distribution system. More than 70 of these terminations have been placed in service since June 1958.