GB313928A - Improvements in and relating to oil-filled cables - Google Patents

Abstract

313,928. General Cable Corporation, (Assignees of Atkinson, R. W., and Simons, D. M.). June 19, 1928, [Convention date]. Cable joints. - Oil-filled cables are connected together while the lengths are maintained full of oil, and the oil in adjacent cable lengths is not in communication. The conductor 13, Fig. 1, having a central oil channel 14 and porous insulation 12 impregnated with oil and an internally fluted lead sheath 4, is capped before jointing to prevent escape of oil by means of a plug 22 and thimble 15 soldered or otherwise attached to close the channel 14, and an insulating tube 8 attached at one end by a bushing 6 to the sheathing 4, and at the other end making joint with the thimble 15 through a pair of abutting rings 17, 18 screwed respectively onto the thimble 15 and into the tube 8. These capping operations may be performed while the cable end is immersed in oil. The thimbles 15 of the adjacent cable ends are connected together by a sleeve 16 having right and left handed screw-threads. Between the tube 8 and the outer Insulating tube 11, which is of wrapped paper with or without a moulded portion 10 and is either slipped on or built up in situ, are arranged condensers 9 comprising plates 28, 29, Fig. 2, connected in series, the outer ring 24 on one being connected to the inner ring 23 of the next, and one end of the series being connected to the sheathing by means of the bushing 6, and the other end to the conductor 13 through contact pieces 20. The series of condensers may be built up as a unit ready for application to the joint. Orifices 37 temporarily closed by a ring 7 place the oil in one cable end in communication with that supplied to the joint casing 1 from reservoirs 40, Fig. 6, having compressible air chambers 41 to allow expansion of the oil without undue variation of pressure. Air under pressure may be supplied from a pipe 44 and oil under pressure from a pipe 42. Connection pipes having valves 43 are provided to enable the oil to be applied to the joint casing 1 either from the reservoirs 40 or direct from the pipe 42. Valve casings 45 situated between the pipe 42 and the joint casings prevent intercommunication of oil from one joint to another by the provision of a valve 46, Fig. 7, that is opened against a spring 48 only when the pressure of oil in the joint casing acting on a diaphragm 47 exceeds a predetermined amount. The valve 53 by which oil passes into the joint casing is restricted either in area or by means of packing 54 to limit the rate of flow of the oil. A terminal structure 30, Fig. 4, comprises an insulating tube surrounding the oil-impregnated insulation 12 and surrounded by a number of condensers 33 connected in series between the conductor 13 and the sheathing 14. An adaptation of the joint for a three-core cable is described. Specifications 7766/14 and 247,143 [both in Class 36, Electricity, Conducting. &c.], are referred to.