US2310423A - Means for preventing leakage of fluid through electric cables - Google Patents

Description

Feb. 9, 1943. R. GOLD 2,310,423

MEANS FOR PREVENTING LEAKAGE OF FLUID THROUGH ELECTRIC CABLES Filed Oct. 25, 1940 i\\\\\ t W X INVENTOR:

Richard Gold Patented Feb. 9, 1943 MEANS FOR PREVENTING LEAKAGE OF FLUID THROUGH ELECTRIC CABLES Richard Gold, Birmingham, England Application October 25, In Great Britain 1940, Serial No. 362,847 October 26, 1939 8 Claims (01. 17477) This invention has for its object to provide improved means for preventingthe leakage of fluid along the interiors of electricv cables.

The invention comprises the combination with a bared portion or portions of the conductor or conductors which has or have 1: en rendered impervious by tinning or otherwise, of a rubber sleeve which is moulded around the conductor or conductors after the latter has or have been coated with any convenient binding agent.

The invention also comprises the combination with the bared portion of the conductor or one or each of the conductors, of a. rigid core piece.

Further the invention comprises the combination with the bared portions of a plurality of the conductors, of one or more distance pieces or spacers.

Moreover the invention comprises the combination with the moulded rubber sleeve, of a metal or other rigid sleeve.

In the accompanying sheet of explanatory drawings:

Figure 1 is a sectional elevation of a cable provided in accordance with the invention with means for preventing leakage of fluid along the interior of the cable.

Figure 2 is a section ure 1.

Figure 3 is a similar view to Figure l illustrating a modified form of the means for preventing leakage of fluid along the interior of the cable.

Figures 4, and 6 are sections taken respectively on the lines 44, 55 and 6-6 of Figure 3.

In Figure 1 the inventionis shown applied to a three-core cable a used for conveying electrical energy to a submersible pump motor and adapted to pass through a stufiing box b on the motor casing. This cable it comprises three stranded-wire conductors c, an insulating sheath or wrapping d on each of the conductors, and an outer or main insulating sheath e in which the individually insulated conductors are enclosed. In applying the invention as shown to the cable a, I remove from that end portion of the cable which is adapted to pass through the stufiing box b, a convenient length of the insulation d, e so as to bare the corresponding portions of the conductors. Preferably the removed length of each inner insulating sheath or wrapping d is of different length and shorter than that of the main outer insulation e so. as to allow end portions of the inner insulating sheaths or wrappings to project to different extents from the adjacent end of the main insulation. To

on theline 2-2 of Figrender the bared portions of the conductors c impervious to moisture they are tinned or otherwise treated over the whole or the greater part of their lengths so as to fill up the interstices between the conductor strands, the filling material being indicated by f in Figure 2. Where the conductors c are of considerable diameter I may remove as shown in Fig. 1 the bared portion of one or each a length of its inner strands and replace them by a solid rod 9 of convenient diameter and slightly greater length than the removed length of conductor strands, the ends of this rod being pointed so that they can be forced into the adjacent parts of the conductor. The tinning or other treatment above mentioned is effected at least over the length of the conductor or conductors from which the inner strands are removed. For holding the bared portions of the conductors c apart in their normal relationship I place over them one more spacers or distance pieces as h in the form of perforated or slotted discs of cured or partly cured rubber, these being slightly smaller in outside diameter than the exterior diameter of the outer insulation k. Also I place over the bared ends of the conductors c, at the position where they enter the motor casing, a vulcanised rubber or other insulating end block i formed with apertures and short tubular projections (which may be of different length) through which the conductors pass. I then mould around the bared portions of the conductors c, between the adjacent end of the outer insulation e and the insulating end block 1' a sleeve k of uncured rubber which also surrounds the projecting ends of the inner insulating sheaths or wrappings d, the distance piece or pieces h and the adjacent portion of the insulating end block, the rubber being caused to enter and completel fill the spaces between the adjacent portions of the conductors. To effect intimate adhesion between the rubber sleeve k and the outer surfaces of the conductors c the latter are treated with any convenient binding agent, such as uncured hard rubber or a solution or dispersion of it or certain rubber derivatives. After the required quantity of rubber has been moulded into position it is vulcanised.

In the manner above described I am able to form in that part of the cable a which is adapted to pass through the stufling box 79 an effective barrier or seal which prevents the creeping along the interior of the cable any moisture which may gain access to its interior.

To prevent bending of the cable a at the position occupied by the seal above described, and

to enable the latter to be tightly secured in. the stuiilng box b I may place around the rubber sleeve is and the adjacent end portion of the cable insulation e a metal or other rigid sleeve m which is united to the rubber sleeve in the vulcanising operation after having its interior treated with a binding agent for effecting intimate adhesion with the rubber sleeve, the binding agent being similar to that employed as above described for treating the bared portions of the conductors c. Preferably the metal or other rigid sleeve m is made in two halves as shown in Figur 2.

;or making a seal between the exterior of the cable a and the stufling box 1; through which it enters the motor casing, I may employ a seal similar to that described in the specification of my co-pending application No. 362,845"Dynamelectric machines, filed October 25, 1940. Thus, jointing material 11 may be placed in the casing 0 of the stuiling box and around the metal or other rigid sleeve m on the moulded rubber end portion of the cable. Also placed in the casing o are a pair of metal pressure rings p, q which bear against the ends of the jointing material and lit closely the annular space between the exterior of the cable sleeve m and the interior of the easing, the ring q being arranged on a shoulder r in the inner end of the casing. By means of an annular nut s screwedinto the outer end of the casing 0 endwise pressure is then applied to the jointing material 12 through the ring p causing the jointing material to seal the stuffing box effectively and prevent the possibility of moisture passing through the stufling box to the interior of the motor.

Figures 3 to 6 illustrate the manner in which.

the invention can be applied to cables of relatively small cross section. Theiseal shown in this example is applied to the junction between a pair of interconnected cables a, a but it is equally applicable to either end or an intermediate porfully reveal the gist of my invention that othem can by applying current knowledge readily adapt it for various applications without omitting features, that, from the standpoint of the prior art fairly constitute essential characteristics of the generic or specific aspects of my invention, and therefore such adaptation should and are intended to be comprehended within the meaning and range of equivalency of the following claims.

I claim:

1. In an electric cable, a plurality oi metallic conductors, a plurality of inner rubber insula-L tions, each of said inner rubber insulations surrounding one of said conductors, an outer rubber sheath surrounding said inner rubber insulations, said inner rubber insulations and said outer rubber sheath being removed from a part of said cable in such a manner that said inner rubber intion of a single cable. In Figures 3 to 6 the cable a is of the three-core round type comprising conductors c, inner insulating sheaths or wrappings d on these conductors, and an outer main insulating sheath 6 as in the previous example, whilst the other cable a is of the three-core flat type comprising conductors c inner insulating sheaths or wrappings 11 and an outer insulating sheath e A convenient length of insulation is removed from the cables a, a at their adjacent end portions which are then spliced together in any convenient manner prior to being tinned or otherwise treated to fill the conductor strands and also treated with a binding agent as in the previous example, the removal of the insulation being effected so that the inner insulating sheaths d, d project towards each other to different extents from the adjacent ends of the main insulation e, e For holding the bared portions of the conductors c, c apart in their normal relationship I wrap around each interconnected pair of such portions a sandwich formed by a sheet u of cured rubber and a similar sheet t of uncured rubber, the uncured rubber being arranged in contact with the bared conductor portions. The rubber sleeve k is then moulded around the bared portions of the conductors c, c and the spacers t, u, and the metal or other rigid sleeve m is placed around the rubber sleeve prior to vulcanisation. Preferably the rubber sleeve k is made to overlap th adjacent ends of the main insulation e, e as shown.

Without further analysis the foregoing will so sulations project from the end faces of said rubber sheath and bared conductor portions are formed between the ends of said inner rubber insulations, and a rubber sleeve vulcanized to said bared conductor portions, to the end faces of said rounding one of said conductors, an outer rubber sheath surrounding said inner rubber insulations, said inner rubber insulations and said outer rubber sheath being removed from a part of said cable in such a manner that said inner rubber insulations project from the end faces of said rubber sheath and bared conductor portions are formed between the ends of said inner rubber insulations, a coating of a binding agent on the outer surface of said bared conductor portions, and a rubber sleeve vulcanized to said bared conductor portions, to the end faces of said rubber sheath, and to the surface of the projecting portions of said rubber insulations, said rubber sleeve intimately adhering by means of said interposed binding agent to the bared surface of said conductors and adhering also to the end faces of said rubber sheath and to the projecting portions of said inner rubber insulations, preventing thereby leakage of fluid along the interior of said cable.

3. In an electric cable, at least one stranded I metallic conductor, the inner wires of which are,

at least partly,-removed, a rigid metallic core arranged within said stranded conductor and replacing said removed inner wires, a metallic coating on said wires and to said rigid core filling the interstices between the non-removed wires and said metallic core and between the k wires themselves, making thereby the stranded conductor liquid-tight in longitudinal direction, and a rubber sleeve vulcanized tov a bared portion of said stranded conductor, said rubber sleeve intimately adhering to the bared surface of said stranded conductor and to the outer surface of said metallic coating, preventing thereby leakage of fluid along the interior of said cable.

4. In an electric cable, at least one metallic stranded conductor, a rubber insulation surrounding said stranded conductor, said rubber cable forming thereby a bared conductor portion, the inner wires of said bared conductor portion being, at least partly, removed, a rigid metallic core arranged within said stranded conductor and replacing said removed inner wires, a metallic coating on said wires and on said rigid core filling the interstices between the not-removed wires and said metallic core and between the wires themselves, making thereby the stranded conductor liquid-tight in longitudinal direction, a coating of a binding agent on the outer surface of said bared conductor portion, and a rubber sleeve vulcanized to said bared conductor portion between the end faces of said rubber insulation, said rubber sleeve intimately adhering, by means of said binding agent, to the bared surface of said stranded conductor and to the outer surface of said metallic coating, preventing thereby leakage of fluid along the interior of said cable.

5. In an electric cable of the type claimed in claim 1, in combination with the bared portions of said conductors, at least one distancing piece holding said bared conductor portions in correct position within the rubber sleeve vulcanized to them.

6. In an electric cable of the type claimed in claim 1, in combination with the bared portions 01' said conductors, at least one distancing piece having the shape of a perforated or slotted rubber disk through the perforations or slots of which said conductors are passing, said rubber disk being arranged normal to the direction of the conductors and holding said bared conductor portions in correct position within the rubber sleeve vulcanized to them.

7. In an electric cable of the type claimed in claim 1, in combination with the bared portions of said conductors, spacers made from cured and un-cured rubber sheets sandwiched together and wrapped around said bared conductor portions with the un-cured rubber in contact with the conductors, said spacers holding said bared conductor portions in correct position within the rubber sleeve.

8. In an electric cable of the type claimed in claim 1, in combination with the rubber sleeve vulcanized to the metallic conductor, a rigid sleeve surrounding said rubber sleeve.

RICHARD GOLD.

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