GB902431A - Improvements in or relating to flexible joints for electric cables - Google Patents

Abstract

902,431. Insulating cable joints. PIRELLI S.p.A. March 18, 1960 [April 30, 1959], No. 9637/60. Class 38 (1). Preparatory to jointing two oil - filled leadsheathed cables, rings 2 of elastic material, e.g. synthetic rubber, are inserted between the lead sheath 1 and insulation 3 to reduce leakage of oil during the jointing operation. Rings 4 located in grooves 6 also act as seals between the sheath 1 and a lead sleeve 9. The cable conductors are connected by a ferrule 5 which, after fitting, has a diameter precisely equal to the diameter of the conductors. The insulation 3 is then stepped back before building up insulation 3<SP>1</SP> by impregnated paper tapes, the direction of winding of alternate layers being of opposite hands. After applying an electrostatic screen formed of carbon paper or metallised paper, impregnated paper tape is applied to form a filling 7 over which are wound two thick paper tapes to protect the screen during the operation of reducing the diameter of the sleeve 9. After soldering the ends of the sleeve to the sheaths of the cables being joined, a rigid metal tube 15 (not shown) split longitudinally in halves is secured around the sleeve 9 to prevent distortion of the latter during evacuation and impregnation of the joint. The tube is then removed and the sleeve reduced in diameter so that it presses against the rings 4. The ends of the sleeve beyond the rings are then removed and the new ends sealed to the sheaths 1 with lead, Fig. 4. The joint is completed by soldering lead bands 11 at either end.