US3848956A

US3848956A - Self-sealing underground tap connector

Info

Publication number: US3848956A
Application number: US00439235A
Authority: US
Inventors: R Kraft
Original assignee: Fargo Mfg Co Inc
Current assignee: Fargo Mfg Co Inc
Priority date: 1972-03-08
Filing date: 1974-02-04
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19

Abstract

A connector for joining a high current capacity tap conductor to an unbroken run conductor in an underground application without removing the insulation from the run cable and which will provide a moistureproof seal at the points of connection of the tap conductor and run conductor.

Description

O United States Patent [111 3,848,956 Kraft Nov. 19, 1974 SELF-SEALING UNDERGROUND TAP [56] References Cited CONNECTOR UNITED STATES PATENTS [75] Inventor: Russell H. Kraft, Hopewell 2,396,119 3/1946 ONeil 339/97 R Junction \lIl/fihfl 339/97 R engen f I [73] Asslgnee 3,111,25 FOREIGN PATENTS OR APPLICATIONS [22] F] d Feb 4 1974 1,924,964 12/1969 Germany 339/98 Ie I [21] Appl. No; 439,235 Prim ary ExaminerJoseph H. McGlynn Related US. Application Data [57] ABSTRACT [63] gf xglz jgg of March A connector for joining a high current capacity tap conductor to an unbroken run conductor in an underground application without removing the insulation 339/98 339/223 i i g from the run cable and which will provide a moisture- [58] Fieid "55 97 99 'proof seal at the points of connection of the tap con- 339/2, 265, ductor and run conducton 10 Claims, 5 Drawing Figures PATENTEL W 1 9W4 3.848.956

SHEET 2 (IF 3 'CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of US. application Ser. No. 232,742, filed Mar. 8, 1972, and now abandoned.

BACKGROUND OF THE INVENTION It has become highly desirable to bury electrical transmission cables underground. Assemblies for such underground applications, for example, connectors wherein a tap conductor is joined to a run conductor, must be specifically designed with this underground use in view. Where direct burial has taken place, the connection of electrical conductors is made and left without benefit of enclosure in the ground or vault frequently. The connector must be moistureproof and proper sealing must be provided. This problem is aggravated by the fact that in underground installations there is a tremendous buildup of pressure due to variations of moisture in the earth and the connector must be designed with this factor being recognized.

A connector whereby a branch tap conductor can be joined to a main run conductor without the necessity of skinning the conductor and at the same time provide a watertight seal, is disclosed in US. Pat. No. 3,579,173; however, the connector shown therein is especially adapted to use with low current capacity taps. The requirement for a satisfactory high current capacity tap has remained. A connector for such use must be easily applied without the use of special tools and provide for installation while the cable is live, provide good mechanical and electrical connections with appropriate moisture seals, have long life underground and be capable of easy disconnect of the tap conductor with a minimum of repair for the run conductor required. Additionally there must be no need of cutting the main cable during installation or skinning either the main run conductor cable or tap conductor and there must be no installation damage to the line or cable resulting from the application of the connector.

SUMMARY OF THE INVENTION i conducting bar extending from one side to another with a conducting bar disposed within the slot, first and second rows of piercing teeth formed on the conducting bar and protruding from the slot, pressure means for pressing the run conductor and tap conductor toward the conducting bar and the teeth through the insulation of the run connector and tap conductor to produce a firm mechanical and electrical connection between the conductor bar and the run conductor and the tap conductor non-conducting idler teeth disposed respectively in spaced relation with said first and second piercing teeth for respectively receiving therebetween said run conductor and said tap conductor and said pressure means pressing the idler teeth into the run conductor and the tap conductor and insulation means respectively surrounding the connections of the tap conductor and run conductor to the conductor bar and the idler teeth.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a selfsealing underground tap connector'constructed in accordance with the teachings of this invention with portions broken away to disclose to view details thereof;

FIG. 2 is a partially exploded longitudinal sectional view of the tap connector shown in FIG. 1 with a run conductor and tap conductor to be connected thereto shown in relative position immediately prior to the making of the connection;

FIG. 3 is a transverse view of the tap connector shown in FIG. 2 taken along the line 2-2 in the direction of the arrows in FIG. 2;

FIG. 4 is a longitudinal sectional view of the tap connector, run connector and tap conductor shown in FIGS. 2 and 3 with the connection completed; and

FIG. 5 is a transverse sectional view taken along the line 5-5 in the direction of the arrows in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT The run conductor which is to be tapped by the tap connector disclosed herein is illustrated in the Figures and indicated by the numeral 10. Cable 10 consists of electrically conducting strands 11 covered by insulation 12. The insulation is of the type commonly used in underground installations such as rubber, plastics and paper. The tap conductor or branch conductor which is to be connected to conductor 10 is indicated in the Figures by the numeral 13 and includes its own insulation 14 around conductor 15. The tap conductor shown in the Figures is also a stranded conductor and the insulation again is of the type commonly used in underground installations.

The tap connector consists of spacer bar 16, conductor bar 17,

clamp pads

18 and 19,

U-bolts

20 and 21,

clamp nuts

22, 23, 24 and 25, conductor

bar sealant pads

26 and 27,

idler members

28, 29, 30 and 31 and

idler sealant pads

32 and 33. I

The spacer bar 16 is molded, hard rubber but can be formed of any suitable non-conducting material. It is provided with

guide channels

34 and 35 and through slot 36 which extends from its upperv surface 37 to its lower surface 38 as seen in the Figures.

Shoulders

39, 40, 41 and 42 project outwardly from the spacer bar 16 to provide

circular openings

43, 44, 45 and 46 respectively for passage of the ends of

U-bolts

20 and 21 therethrough. A

The conductor bar 17 is formedof soft aluminum with a body configuration such that it fits snugly within slot 36 which is shaped to receive it with upper and lower rows of piercing teeth protruding from the spacer 16 at

surfaces

37 and 38. There are two upper rows of teeth and these are designated in the figures by the

numerals

47 and 48. Each row has a multiplicity of teeth with teeth of respective rows arranged side by side in ther side of the longitudinal center line of the conductor bar 17 at surface 38 so that the outer edges of adjacent lower teeth define a line and the lines so defined by each pair of lower teeth all lie in a single plane which, of course, is a different plane than the plane in which the outer edges of the upper teeth lie.

The lower teeth are substantially identical to the upper teeth; however, in the embodiment disclosed herein, as is best seen in FIGS. 3 and 5 the upper teeth are somewhat larger than the lower teeth since it is intended that the run conductor which is of larger diameter than the tap conductor will be applied at the upper surface as seen in the Figures and to the upper teeth with the tap conductor 13 being connected at the lower surface and to the lower teeth of the conductor bar.

The slot 36 in spacer bar 16 is formed to hold the conductor bar 17 in a snug, tight fit which, due to the elastomeric material of the spacer bar, allows the con- .ductor bar to float and allow for adjustment to the cable and line.

The

clamp pads

18 and 19, together with the

U-bolts

20 and 21 and associated

nuts

22, 23, 24 and 25, provide a pressure means for pressing the cable and line 13 toward the conductor bar and pressing the cable 10 toward

upper teeth

47 and 48 and the line 13 toward the

lower teeth

49 and 50 which presses the teeth through the insulation of the run conductor and tap conductor to produce a firm mechanical and electrical connection.

Idler

members

28, 29, 30 and 31 are also formed of non-conducting material, although other material can be used, with each having a row of transverse protruding teeth such as teeth 51 of idler member 28, teeth 52 of idler member 29, teeth 53 of idler member 30 and teeth 54 of idler member 31. The teeth are formed I somewhat arcuately in the transverse direction.

The

idler teeth

51, 52, 53 and 54 convey the compressive force from the outside plates directly to the conductor itself since these teeth also pierce adjacent conductor insulation when the

nuts

22, 23, 24 and 25 are tightened on the U-bolts. The firm balanced grip prevents creep and movement and results in a firm mechanical hold. In certain designs it may be desirable to have the smaller or fixed part of a clamping device in which case there will only be piercing members on one side of the connector.

The piercing teeth of the conductor bar consists of a soft aluminum tooth configuration shaped to cut through the conductor insulation and then fold around the internal strands without causing damage to the strands, thus the conductor is not damaged because of penetration and the contact area is increased. Since this piercing tooth concept does not cause conductor damage, it is possible to provide multiple teeth to increase the current transfer capabilities of the connector.

Teeth can be provided to pierce the conductor insulation at different points around the circumference, such-as top and bottom, triangular configuration, or to provide a cradle effect to maintain all mechanical pressures on the metallic strands and eliminate mechanical pressure on the insulating material. With all of the contact pressure exerted by teeth on the strands the nature of the insulation becomes a neglible factor in maintaining contact pressure. Since different insula- 4 tions have varying flow characteristics under pressure and temperature variations it is most desirable to avoid reliance on this insulation as a permanent component in the contact pressure system.

When this approach of placing teeth around the cir-- cumference of the metallic strands is used, the teeth can be metallic where current flow is desired and nonmetallic where insulating characteristics are required.

Non-metallic teeth can be made with the same configu- I ration as the soft aluminum teeth and fabricated of a material that is softer than the metallic strands so that it will fold over these strands without causing any physical damage.

Each of the clamp pads is provided with a guide channel such as guide channel 55 in pad 18 and guide channel 56 in pad 19. The guide channels are arcuate bands centrally of the clamp pads which in the case of pad 18 channel 55 overlies guide channel 34 in the spacer bar and in the case of clamp pad 19, the guide channel 56 overlies or faces guide channel 35in the spacer bar. Additionally holes are provided in the clamp pads allowing the legs of the

U-bolts

20 and 21 to pass therethrough as well as through the holes in the spacer bar to allow threaded end portions of the legs of the U-clamps to be engaged with

nuts

22, 23, 24 and 25. For the sake of simplicity, each of the holes in pad 18 are indicated by the numeral 57 and each of the holes in the pad 19 are indicated by the numeral 58.

The

sealant pads

26, 27, 32 and 33 are rectangular, soft easy flowing elastomeric members each of which is provided with a central rectangular slot through which teeth can project and which provide automatic sealing making the unit waterproof for direct burial in any type of soil, wet or dry. Pad 26 is provided with slot 59 through which

teeth

47 and 48 project to embrace main cable 10 and pad 32 is provided with slot 60 through which teeth 51 and 52 can project to also embrace run conductor 10. Pad 27 is provided with slot 61 through which

teeth

49 and 50 can project to embrace tap conductor 13 and pad 33 is provided with slot 61 through which

teeth

53 and 54 can project to also embrace tap line 13. The pads, when used, provide water insulation means surrounding the rows of piercing teeth. When'the pads are not used, this insulation is provided by the pressing of the insulation of the conductor directly against the tooth bearing members.

In assembling, the run conductor or main cable is wiped clean and dry in the area where the tap is to be made. The end of the tap conductor can be sealed by a standard commercial tap or with tape. The combination of the spacerbar, conductor bar, idler members, clamp pads and U-clamps is taken and the clamp nuts, top pad 18 and

idler members

28 and 29 are removed. Spacer bar 16 is then raised high enough to thread the tap line 13 into position in channel 35 together with

idler members

30 and 31 and sealant pad 33, and the sealant pad 27 is placed between the spacer bar 16 and the tap line 13. The spacer is then pressed downwardly and pad 26 placed in position with

idler member

28 and 29 and pad 32 and the connector held up against the main cable. Clamp 18 is then placed in position over the cable and the nuts 22, 23, 24 and 25 are tightened. The connection is then complete.

It is seen that there has been no necessity to cut the run conductor or skin or remove insulation from either the run conductor or the tap conductor. The soft aluminum piercing teeth of the conductor bar cut through the insulation of the run conductor and tap conductor with minimum damage to the insulation with the piercing teeth deforming around the harder aluminum strands of the conductors. These teeth do not cut or damage in any way the current capability of the run conductor since the material from which these teeth are formed is softer than the material from which the conductor strands are formed. The piercing teeth, however, being stronger than the insulation surrounding either the run conductor or the tap conductor can readily pass through this insulation.

The multiplicity of piercing teeth increases the contact area on the strands of the respective conductor making electrical contact with numerous strands making a safe, high current connection. By multiplying the number of teeth or contact surfaces along with increased contact surface due to the use of soft material teeth increases the current capabilities of the device making it a full or high current device rather than a limited current device as are presently existing products. No special tools are required for the installation and no extreme forces or special knowledge is needed to install. The double rows of teeth aids in centering the respective run or tap conductors on the conductor bar and the floating of the conductor bar aids this. The teeth provide a short, direct current transfer path and the mass of the conductor bar, together with the metal in the conductors, acts as a heat sink and conducts heat away from the contact teeth thereby deterring excessive heat buildup at the contact surfaces. The teeth are driven through both conductors simultaneously and the connection can be made to an energized run conductor with no special precautions. The seal is completed before the teeth completely penetrate the cable insulation and the energized parts are never exposed thereby minimizing danger to the installer. The U-bolt clamping mechanism assures positive rigid connection in a systern able to withstand forces which pull, bend and tend to flex the conductors.

The idler teeth (top and bottom) of non-conducting material are added to convey the compressive force without pressing on a soft non-rigid material such as the cable insulation. The idlers provide a clamping chain from U-bolt to plate to idler teeth to tap conductor strands to piercing bar (and teeth) to run conductor strands to idler teeth to tap plate to nuts. This chain will maintain clamping pressure, ensuring a more permanently tight and good connection.

In the event the tap conductor is to be disconnected or otherwise discarded, all parts of the connector can be removed and the run conductor strands are left undamaged and only the insulation thereof needs to be repaired to provide a watertight seal over the tooth holes in the insulation. When the sealant pads are used, pressure applied will squeeze out any excess of the pad so that they enhance rather than interfere with the creation of a good insulation means. Thus, a tap connector for large current capacity tap connections has been provided.

I claim:

1. A connector for joining a tap conductor to a run conductor in which said tap includes a spacer bar formed of a non-conducting material, first and second surfaces of said spacer bar, a slot formed in said spacer bar extending from said first to said second surface, a conductor bar disposed within said slot, first and second groups of piercing teeth formed on and extending from said conductor bar protruding from said slot at said first and second respective surfaces of said spacer bar, a first idler member of said tap, first non-electrical conducting idler teeth of said first idler member disposed in spaced relation with said first group of piercing teeth for receiving said cable therebetween, a second idler member of said tap, second non-electrical conducting idler teeth of said second idler member disposed in spaced relation with said second group of piercing teeth for receiving said conductor therebetween pressure means for pressing said first group of piercing teeth and said first idler teeth and said second group of piercing teeth and said second idler teeth toward each other whereby said first and second groups of piercing teeth respectively pierce through the insulation of said run conductor and said tap conductor to produce a firm mechanical and electrical connection between said conductor bar and said run conductor and said tap conductor, and said first and second idler teeth respectively pierce through the insulation of said conductor and said line to produce a firm mechanical connection, and first, second, third and fourth insulation means respectively surrounding said first and second groups of piercing teeth and said first and second idler teeth.

2. A connector for joining a tap conductor to a run conductor in accordance with claim 1 in which said first and second insulation means are respectively the insulation of said run conductor and said tap conductor respectively embracing said spacer bar.

3. A connector for joining a tap connector to a run conductor in accordance with claim 1 in which said spacer bar is formed of an elastomeric material so that said conductor bar is maintained in floating relationship thereby.

4. A connector for joining a tap conductor to a run conductor in accordance with claim 1 in which said pressure means includes first and second clamp pads respectively embracing said .cable and said line and drawn together by bolt means.

5. A connector for joining a tap conductor to a run conductor in accordance with claim lin which said first insulation means is a first elastomeric pad surrounding said first group of piercing teeth with a slot formed therein through which said teeth project with one side of said pad embracing the insulation of said main or run conductor and the remaining side thereof embracing said first surface, said second insulation means is a like pad surrounding said second group of piercing teeth through which said teeth project with one side of said pad embracing the insulation of said tap conductor and the remaining side thereof embracing said second surface and said third and fourth insulation means respectively surround said first and second idler teeth embracing said run conductor and said tap conductor respectively and said pressure means.

'6. A connector for joining a tap conductor to a run conductor in accordance with claim 5 in which said pressure means includes first and second clamp pads respectively embracing said run conductor and said tap conductor and said third and fourth insulation means respectively embrace said first and second clamp pads.

7. A connector for joining a tap conductor to a run conductor in accordance with claim 1 in which said piercing teeth can pierce the insulation of said cable and said tap conductor and are formed of a material conductor in accordance with claim 7 in which said idler teeth can pierce the insulation of said run conductor and said tap conductor and are formed of a material which is softer than the conducting material of said run conductor and said tap conductor whereby said teeth can readily pierce the insulation without damaging the conducting material of said run conductor and said tap conductor and allowing said teeth to deform and embrace the conducting material. I

9. A connector for joining a line to a cable in accordance with claim 7 in which each of said first and sec ond groups of teeth has a multiplicity of teeth with teeth of respective groups arranged in rows with teeth of respective rows arranged side by said in transverse orientation on either side of the longitudinal center line of the conductor bar.

10. A connector forjoining a line to a cable in accordance with claim 9 so that the outer edges of adjacent teeth in each of said rows defines a line and the line so defined by each pair of teeth all lie in a single plane.

Claims

1. A connector for joining a tap conductor to a run conductor in which said tap includes a spacer bar formed of a non-conducting material, first and second surfaces of said spacer bar, a slot formed in said spacer bar extending from said first to said second surface, a conductor bar disposed within said slot, first and second groups of piercing teeth formed on and extending from said conductor bar protruding from said slot at said first and second respective surfaces of said spacer bar, a first idler member of said tap, first non-electrical conducting idler teeth of said first idler member disposed in spaced relation with said first group of piercing teeth for receiving said cable therebetween, a second idler member of said tap, second nonelectrical conducting idler teeth of said second idler member disposed in spaced relation with said second group of piercing teeth for receiving said conductor therebetween pressure means for pressing said first group of piercing teeth and said first idler teeth and said second group of piercing teeth and said second idler teeth toward each other whereby said first and second groups of piercing teeth respectively pierce through the insulation of said run conductor and said tap conductor to produce a firm mechanical and electrical connection between said conductor bar and said run conductor and said tap conductor, and said first and second idler teeth respectively pierce through the insulation of said conductor and said line to produce a firm mechanical connection, and first, second, third and fourth insulation means respectively surrounding said first and second groups of piercing teeth and said first and second idler teeth.

4. A connector for joining a tap conductor to a run conductor in accordance with claim 1 in which said pressure means includes first and second clamp pads respectively embracing said cable and said line and drawn together by bolt means.

5. A connector for joining a tap conductor to a run conductor in accordance with claim 1 in which said first insulation means is a first elastomeric pad surrounding said first group of piercing teeth with a slot formed therein through which said teeth project with one side of said pad embracing the insulation of said main or run conductor and the remaining side thereof embracing said first surface, said second insulation means Is a like pad surrounding said second group of piercing teeth through which said teeth project with one side of said pad embracing the insulation of said tap conductor and the remaining side thereof embracing said second surface and said third and fourth insulation means respectively surround said first and second idler teeth embracing said run conductor and said tap conductor respectively and said pressure means.

6. A connector for joining a tap conductor to a run conductor in accordance with claim 5 in which said pressure means includes first and second clamp pads respectively embracing said run conductor and said tap conductor and said third and fourth insulation means respectively embrace said first and second clamp pads.

7. A connector for joining a tap conductor to a run conductor in accordance with claim 1 in which said piercing teeth can pierce the insulation of said cable and said tap conductor and are formed of a material which is softer than the conducting material of said run conductor and said tap conductor whereby said teeth can readily pierce the insulation without damaging the conducting material of said cable and said line and allowing said teeth to deform and embrace the conducting material thereby increasing the contact surface.

8. A connector for joining a tap conductor to a run conductor in accordance with claim 7 in which said idler teeth can pierce the insulation of said run conductor and said tap conductor and are formed of a material which is softer than the conducting material of said run conductor and said tap conductor whereby said teeth can readily pierce the insulation without damaging the conducting material of said run conductor and said tap conductor and allowing said teeth to deform and embrace the conducting material.

9. A connector for joining a line to a cable in accordance with claim 7 in which each of said first and second groups of teeth has a multiplicity of teeth with teeth of respective groups arranged in rows with teeth of respective rows arranged side by said in transverse orientation on either side of the longitudinal center line of the conductor bar.

10. A connector for joining a line to a cable in accordance with claim 9 so that the outer edges of adjacent teeth in each of said rows defines a line and the line so defined by each pair of teeth all lie in a single plane.