GB832312A - Improvements in the electrical insulation of electric cables - Google Patents

Abstract

832,312. Cables. ALLMANNA SVENSKA ELEKTRISKA A.B. March 20, 1958 [Sept. 10, 1957], No. 8912/58. Class 36. Oil in a cable 1 is circulated by a pump 4 through a return pipe 5 which leads to a throttling device 7 and an expansion chamber 6. As the oil expands into the chamber 6 it becomes freed from gases absorbed from the insulation during its passage through the cable. A pump 8 maintains a vacuum in the chamber 6. The device 7 may consist of a number of nozzles from which the oil is sprayed into the chamber 6. A cooling arrangement 9 and a filter 10 may be included in the pipe 5. Fig. 5 shows an arrangement for a vertical cable 1 having electric connections at 20 and a pump 4 and return pipe 5 for oil that has been freed from gases in the vacuum chamber 6. Chamber 6 may be provided with a pressure indicator relay 17 serving as an oil control. The pipe 5 is separated from the cable conductors by isolators 11. The oil may be regenerated in the tank 6 or in a separate vessel in the pipe 5 by filtering through fuller's earth, or by contact with lime when the cable insulation consists of chlorinated diphenyl. Fig. 6 shows a cable in which a central channel 12 is formed by the conductors 13, and channels 14 are provided under the lead sheath 15 so that the oil can flow in a radial direction through the insulation which may consist of paper.