US2556906A - Compression cable system - Google Patents

Description

June 12, 1951 w. A. DEL MAR COMPRESSION CABLE SYSTEM Filed June 50, 1949 INVENTOR WILL/AM A DEL MAR ATTO N Patented June 12, 1951 UNITED STATES PATE.

OFFICE COMPRESSION CABLE SYSTEM Application June 30, 1949, Serial No. 102,258

3 Claims. 1

My invention relates to a system of electric cables wherein the cable is maintained under pressure of a gas and wherein the cable is terminated in a pothead or terminal, the interior of which contains oil which is, likewise, maintained under pressure.

In such a system it is customary to equalize the gas pressure under which the cable is maintained and the pressure on the terminal oil, by means of a pressure equalizer having a movable diaphragm, one face of which is in contact with the gas and the other in contact with the oil. It is obvious that with such an arrangement the volume of the oil space will increase when the gas pressure drops and, as the volume of oil is constant, the level of the oil in the terminal will fall, thereby exposing the terminal to electrical failure.

It is, therefore, very desirable to modify the equalizer system to prevent such happening and it is the object of the present invention to accomplish this.

The importance of the invention is due to the fact that compression cables are able to operate, without detriment, for limited periods, with quite low gas pressure in the pipe, whereas oil-filled terminals will not operate without being filled with oil. Such low pressure in the pipe may be the result of a leak and it is important to be able to keep the cable in operation until the leak has been located and repaired.

The present invention overcomes these defects and provides a means whereby a cable may be kept in temporary operation.

The foregoing and other features of my invention-will now be described in connection with the accompanying drawing forming part of this specification in which I have illustrated my cable system in its preferred form, after which I shall point out in the claims those features which I believe to be new and of my own invention.

In the drawings:

Figure l is a diagrammatic sketch of my me ferred cable system.

Figure 2 is a diagrammatic sketch showing a solenoid operated pressure relief valve.

Figure 3 is a modification of my equalizer which I may employ.

Referring to Figure 1., II is a pipe containing gas under high pressure, normally about two hundred pounds per square inch; i2 is a terminal or pothead containing oil; I3 is a cable; I4 is a gland surrounding the cable I3 and separating the oil in [2 and the gas in II. I5 and I6 are pressure equalizers consisting of a flexible member I1 and I8 and rigid containers I9 and 29 respectively. 2! is a pipe connecting the collapsible member I? with the pipe II containing the cable i3. 22 is a valve in the pipe 2| which may be held open by the gas pressure in the pipe II when that pressure is in excess of a predetermined value, such as pounds per square inch above atmosphere, and closes when the pressure in the pipe falls below that predetermined value.

In Figure 1, I show a valve 22 in pipe 2I which is connected to the valve by pipe 31. A spring 3?. meves the piston 33. As will be readily understood, the piston 33 is normally held by the gas pressure in the system so that the opening 34 maintains clear passage from pipe II to pressure equalizer I 5 through passage 2i. When the pressure in pipe Il drops to a predetermined value, the piston 33 moves under pressure of spring 32 and closes the Valve 22 and the passage 2|.

In the modification illustrated in Figure 2, I show an electrically operated valve 22 having a moving piston 33 with opening 34 therein permitting gas from I l to flow to pressure equalizer I5. The piston 32 is provided with a solenoid 44 which is energized from source of power 4| when switch 42 is closed. This switch 42 is operated by a spring 43 when the pressure in pipe II drops below a predetermined level.

In the diagram Figure l, I illustrate pressure equalizers having flexible membranes I! and I8 made of rubber or other suitable flexible material. In Figure 3, I show a collapsible metal bellows 5! within a container 52. The bellows is connected to pipe II through pipe 2! and the container 52 is connected to the other container by pipe 23, all as shown in Figure 1.

Under normal operating conditions there will be minor variations of pressure in the pipe I I due to changes in temperature of the cable and of the ambient medium around the pipe, be it air or earth. These variations of pressure will be communicated from the interior of the member I I to the oil in IS and 2t and thence through the member I8 to the oil in the pothead l2, through the pipe 24. Thus, the pressures in pipe I I and pot-- head I2 will, at all times, be substantially equal as long as the pressure of the pipe gas above atmospheric pressure is sufiiciently high to keep open the valve 22.

In the event of the pressure in the pipe I! falling below, say 100 pounds per square inch above atmosphere, the valve 22 will close and equalization of pressure will stop. If the cable is continued in operation at low pressure, there will be variations in pressure of the oil in the pothead I2, due to changing load or changing ambient temperature. If the pressure in I2 should rise, oil will be forced out through 24% to Hi and pressure will be applied to the oil in 26 through 23 to l9 whereby the gas in the chamber ll will be put in compression. This will act as a cushion to prevent the building up of excess pressures which might endanger the pothead. If the pressure in l2 should drop while 22 is closed, the gas in chamber I! will expand and keep up the level of the oil in l2.

The reason for using two equalizers rather than one, is that if the equalizer i6 were omitted, there would be only one thin Wall between the gas and terminal oil. A rupture of" thiswall' would result in filling the potheads with gas. With two equalizers, if either should fail, there will remain a separating wall between. oiland. gas.

I wish it distinctly understood that my cable system, herein illustrated and. described is in the form which I desire to make and use it and that changes or variations may be made as may be desirable or convenient without departing from the salient features of my inventionand I therefore intend the following claims to cover such modifications as naturally fall within the lines of invention.

Iclaim:

1-. A compressioncablesystem of the class described comprising a pipe containing one or more cables and including gas under pressure of normally not less than 100 pounds per square inch,

a terminal. containing 011 under pressure at the end of the cable, a gland around. the cable separating the gas in the pipe from the oil in the terminal, a pair of equalizers disposed in series connected to the terminal and pipe, whereby the oil in the terminals is normally maintained at substantially the same pressure as the gas in the pipe, and an automatic valve between the pipe and the equalizer, which valve automatically closes when the pressure in the pipe falls to a predetermined value in relation to atmospheric pressure.

2. A compression cable system of the class described, comprising a pipe containing an electrical cableand including gas within the pipe under pressure of normally more than one hundred pounds per square inch, a terminal containing oil under pressure at the end of the cable, a gland around the cable separating the gas in the pipe from. the oil in. the terminal, a pair of equalizers disposed in series connected to the terminal andpipe; whereby the oil in the terminal is main- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES I PATENTS Number Name Date 2,079,856 Ho'ChStadter May 11, 1937 2,174,961 Bennett Oct. 3, 1939 2,427,627 Shiroyan Sept. 16, 1947 2,438,441 I-Iollingsworth Mar. 23, 1948

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