GB2243254A

GB2243254A - Spacer for joint of two or more cables or cable cores

Info

Publication number: GB2243254A
Application number: GB9105453A
Authority: GB
Inventors: Frank Freiwald; Dieter Hellbusch
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1990-04-14
Filing date: 1991-03-14
Publication date: 1991-10-23
Anticipated expiration: 2011-03-14
Also published as: GB9105453D0; DE9004349U1; GB2243254B

Abstract

A spacer (70) for two or more cables or cable cores (10a, 10b, 10c), comprising a star-shaped body (72; 32) of stiff material having radial arms (77, 78, 79; 134, 136, 138) locating the cores or cables at a predetermined distance from each other, and an annulus (74, 76; 110) of stiff material encompassing said cables or cores. The annulus is connected to said star-shaped body to form a unit therewith. The annulus may be formed of interlocking parts. <IMAGE>

Description

SPACER FOR TWO OR MORE CABLES OR CABLE CORES The invention refers to a spacer to two or more cables or cable cores, in particular for medium voltage cables or cable cores.

The German patent specification 23 31 672 discloses a star-shaped spacer for three cable cores in a cable connection. The radial arms of the known spacer are dimensioned to support a metallic sleeve encompassing the cable connection. By this, the cable cores are retained at a predetermined distance from each other and from the metallic sleeve. Owing to the relatively large length of the arms, the known spacer is difficult to assemble. Further, the known spacer is not in a position to withstand the radially outwardly effecting forces on the cable cores upon a dynamic short-circuit current.

Various spacers are disclosed by the German patent specification 14 90 263. One embodiment refers to an annular spacer having an inner diameter which allows the annular member to be displaced on the inner sheath of the cable into a parking position prior to its final installation. The inner side of the known spacer includes circular recesses for the receipt of cable connectors. Another embodiment includes a circular disc-like spacer having three keyholeshaped openings, the smaller portion of the openings being adapted to receive a cable connector while the larger portion is dimensioned to receive the insulation of a cable core in a parking position of the spacer. A third embodiment provides a spacer for each cable core having also a keyhole-like aperture. In all cases, the known spacers have to be assembled and be brought into a parking position before the cable connection is made.

The German patent specification 27 10 848 discloses a spacer for a medium voltage cable wherein three loopshaped portions are located within a sleeve and fixed by means of a central axially extending rod. With the known spacer, the cable cores are safely held in radially outward and inward direction, however, the assembling of the spacer is relatively complicated. With the known spacer, air bubbles which affect the insulation properties may be left after filling out the cable connection with a gelling medium.

The object of the invention is to provide a spacer for two or more cables or cable cores which can be simply manufactured and assembled and which secures a defined position of the cable or the cable cores radially inwards and outwards. Furthermore, the spacer must not affect the electrical properties of the cable connection.

The spacer according to the invention is a composite structure and consists of at least two parts hinged or plugged together to capture the cables and restrain them against radial movement inwardly or outwardly. One embodiment comprises a star-shaped body and an annular member encompassing the cable or the cable cores. The star-shaped body and annular member are designed such that they can be interconnected to form a unit which is preferably rigid in at least the radial direction. The star-shaped body can also be assembled easily after the cable connection has been installed. In case the annular member is an integral element, it has to be placed on the cable or the cable cores into a parking position prior to the installation of the splice. Due to the relatively large inner diameter of the annular member, such handling meets no problems.After the cable connection has been made, annular member and star-shaped body are put together so that the cables or the cable cores obtain a defined position and are fixedly secured against radially inwards and outwards movement.

Different structural designs are conceivable to interconnect star-shaped body and annular member. According to an embodiment of the invention, star-shaped body and annular member are adapted to be interconnected through at least one tongue and groove joint. According to another embodiment of the invention, star-shaped body and annular member have engageable connection portions effecting a tight fit. It is understood that also a groove and tongue joint may include a tight fit. According to a specific embodiment of the invention, at least one arm of the star shaped body has an outer extension coacting with a complementary recess of the annular member. The extension for example can be received by the recess of the annular member in a snug or tight fit.Inversely, the annular member may be provided with at least one radially inwardly facing extension which coacts with a complementary recess in one arm of the star-shaped body.

According to another embodiment of the invention, the extension or the recess can include a coaxial projection, preferably a pin adapted to be accommodated by a complementary recess or a corresponding bore in the recess or the extension, respectively. By this, both parts of the spacer according to the invention can be additionally fixed, in particular if according to a further embodiment of the invention, the pin is conically shaped.

According to a preferred embodiment of the invention, the wire spacing member is a composite and consists of at least two segments which can be hinged or plugged together such that the annular member may be subject to loads in circumferential direction. A split or hinged annular member has the advantage that it does not need a parking position, it rather can be assembled after the cable connection has been made. The annular member serves for the positioning of the star-shaped body and resists radially outwardly effecting forces, for example in case of a dynamic short circuit current. The segments of the annular member are to be interconnected such that a load in the circumferential direction does not separate the segments. As to this, different embodiment or structural designs are conceivable.

The segments can have recesses or extensions which coact in a positive or non-positive engagement in order to resist the described forces. Preferably, a pin and socket connector is provided such that a coaxial pin at one end of a segment coacts with a coaxial bore of the adjacent segment.

If the spacer according to the invention is used for three cable cores or cables the annular member can consist of two identical segments. This facilitates the manufacture of the annular member, particularly if it is made of injection-molded plastic material as for example may be also the case for the star-shaped body.

In case the spacer according to the invention is used for cable connections where the splice is encompassed by a metallic sleeve, a further embodiment of the invention provides that the outer diameter of the annular member substantially corresponds to the inner diameter of the sleeve. By this, the annular member serves for the radial support of the sleeve and holds the sleeve at an accurate distance from the cables or cable cores throughout its circumference. With such cable splices, the annular member can be used solely in order to maintain the sleeve at a predetermined distance from the cable cores. In this case, the annular members are preferably placed in the end portions of the metallic sleeves.

The spacer according to the invention can be simply manufactured e.g. by injection molding. With the spacer according to the invention, the cables or cable cores achieve a defined position radially inwards and outwards. The spacer according to the invention can be simply installed and can be shaped very flat so that the danger of air bubbles being left upon filling out the cable connection with a liquid finally gelling substance does not exist. Spaces between the cables and the annular member and/or the star-shaped body or through holes in the parts of the spacer allow the liquid substance to flow into all areas of the cable connection.

The invention is explained in more detail with reference to the accompanying drawings.

Fig. 1 is a perspective view partially broken of a cable connection including a metallic sleeve and spacers according to the invention.

Fig. 2 is an exploded plan view of a spacer of the cable connection of Fig. 1.

Fig. 3 is a plan view and Fig. 4 a side view of a segment of an annular member of a second embodiment according to the invention.

Fig. 5 is a plan view and Fig. 6 a side view of a star-shaped body for the second embodiment according to the invention.

In Fig. 1, three plastic-insulated cables 10a, 10b, 10c are connected with a paper-insulated cable 11. The connection of the conductors is not shown and is made in a conventional manner. Shrink sleeves 4Oa, 4Ob, 40c, respectively, are placed on the electrical connection of the conductors. A sleeve 42 of metallic material is wrapped around the shown cable connection, the longitudinal edges of the splitted sleeve being bent outwardly (reference is made to the prior German patent application P 39 05 441.1).

Two rail portions 43, 44 are U- or C-shaped in cross section and have legs inclined inwardly. The legs grip behind the bent longitudinal edges of the sleeve 42 and define a kind of dovetail connection. Sealing elements 45, 46 are placed on cables 10a, 10b, 10c, respectively and on the lead sheath 33 of cable 11 at the ends of sleeve 42.

The sealing elements 45, 46 consist of resilient closed cellular foamed plastic material. The sealing elements are not described in detail since they are subject matter of the German patent application P 39 05 441.1 and the Gebrauchsmuster application G 89 12 585, respectively.

The braids 18a, 18b, 18c made of the screen of the plasticinsulated cables 10a, 10b, 10c are led outside of sleeve 42 and can be electrically connected with the sleeve 42 by means of a sheet screw 59. The ends of the braids 18a, 18b, 18c are brought into electrical engagement with the lead sheath 33 by means of a constant force spring 60 so that a short circuit current connection is established between cables 10a, 10b, 10c on the one side and cable 11 on the other side.

The rail portion 44 receives an adapter 61 of plastic material within an opening, an opening of the adapter can be closed by a cap 62. The adapter 61 serves for receiving a pouring spout of the bag for the casting mass indicated at 64. The casting mass is poured into and completely fills out the cavity formed by sleeve 42 and the sealing elements 45, 46.

As can be further seen in Fig. 1, a spacer 70 is located in the area of shrink sleeves 40a, 40b, 40c which is to be described in more detail with the aid of Fig. 2.

The spacer 70 consists of a star-shaped body 72 and an annular member encompassing body 72 and consisting of two segments 74, 76. The parts 72, 74 and 76 are relatively flat and made by injection molding. The star-shaped body 72 has three arms 77, 78, 79 spaced about of 1200 which define circular arc-profiled recesses 80 adapted to receive the shrink sleeves 40a, 40b, 40c as can be seen in Fig. 1.

The star-shaped body 72 can be easily installed after the cable connection shown in Fig. 1 has been established.

Radial extensions 81, 82, 83 are formed to the outer ends of arms 77, 78, 79, one side thereof being flush with a front surface of body 72, the other side forming a step at 84. The extensions 81 to 83 include pins 85 which are conically formed and extend coaxially perpendicularly to the drawing plane.

Segment 74 includes an extension 86 at one end thereof having a surface which is offset with respect to the front surface of the segment and which has a bore 87. At the other end, the segment 74 has an extension 88 which also has a second offset surface which faces away from the onlooker as indicated by the dashed line. A pin 89 is provided in the area of extension 88 coaxially extending perpendicular to the drawing plane. A recess 90 is located on the same side as the offset surface of extension 88,and includes a bore 91. Segment 74 includes two spaced circular-arc-shaped recesses 92, 93 at the inner side.

Segment 76 has an extension 94 at the upper end including a pin 95 coaxially extending perpendicular into the drawing plane. On the other end, segment 76 includes an extension 96 having a bore 97. The extensions 94, 96 have surfaces on opposing sides offset with respect to the front surfaces of segment 76. Segment 76 also includes two recesses 98, 99 having bores 100, 101. Segment 96 includes a circular arc-shaped recess 102 at the inner side.

On account of the described extensions 86, 94 and 88, 96, the segments 74, 76 can fittingly engage corresponding bores 97, 87 by the pins 89, 95. Since pins 89, 95 have a conical shape, they form a tight fit with the corresponding bores. The extensions 81, 82, 83 of the star-shaped body 72 can be inserted in corresponding recesses 90, 98, 99 of segments 74, 76 and define a tight fit. The pins 85 of the extensions 81 to 83 engage bores 91, 100, 101 in a tight fit. Thus, star-shaped body and annular member form a unit by which the interconnected cores or cables of the cable connection of Fig. 1 can be held at a predetermined distance from each other. In the described connection, the recesses 80 of the star-shaped body 72 are oriented to the recesses 92, 93, 102 such that the shrink sleeves 40a, 40b, 40c can be received by the circular openings formed by the mentioned recesses.The outer diameter of the ring formed by the segments 74 and 76 corresponds to the inner diameter of sleeve 42 so that a predetermined distance of sleeve 42 with respect to the cable cores or the cable is maintained.

As can be seen further, the spacer ring made by segments 74, 76 can be assembled and connected with the star-shaped body 72 after the cable connection is made. The annular member formed of segments 74, 76 can be applied to without using the star-shaped body in order to support sleeve 42 its circular form. Such annular members can be seen at 110 and 112 in Fig. 1. The annular spacers are placed adjacent sealing elements 45, 46. Also the annular members 110, 112 can be assembled after making the cable connection prior to the installation of sleeve 42.

Figs. 3 through 4 show a modification with respect to the spacer of Fig. 2. The annular member consists of two identical semi-circular segments one of which being shown at 110. Extensions 112, 114 are formed to the ends of the segment which include recesses 116, 118 formed by surfaces offset with respect to the front surfaces of the segment.

Recess 116 faces the onlooker while recess 118 is located on the opposite side as shown by the dashed line. A short pin 120 is formed in recess 116 extending coaxially. Recess 118 has a bore 122 matching to pin 120. Segment 110 includes further three recesses 124 angularly spaced about 600, each including a bore 126. An identical second segment 110 which is turned about the axis 130 from the shown position of segment 110 serves for the completion an annular member, with adjacent extensions 112, 114 fittingly engaging each other and the pins 120 coacting with bores 122.

As can be seen, the finished annular member has a circular contour at the inner side.

In Fig. 4, a star-shaped body 132 can be seen having arms 134, 136, 138 between circular-arc-shaped recesses 140, 142, 144. Arms 134 to 138 have radial extensions 146, 148, 150 which are recessed from the front side of star-shaped body and on the other end are flush as can be seen in the left side view. The extensions 146 to 150 coact with corresponding recesses 174 of segments 110 in that they are accommodated by the recesses 124 in a snug or tight fit.

The pins 152 engage the bores 126. Since an annular member formed by segments 110 has six recesses 174, the starshaped body 132 can be mounted to the annular member at angular positions spaced about 600.

Similar to the spacer of Fig. 2, the spacer 132 can be made relatively flat and manufactured by injection molding of plastic material. It can be applied in the same manner as shown in connection with Fig. 1. The thickness of the annular segments and the star-shaped body corresponds to the depth of the cogresponding recesses. The unit of starshaped body and annular member, thus, has smooth step-free front surfaces after assembly.

The recesses 80 or 140, 142, 144 have a larger dimension than the cables wherby the liquid substance filled in as described in connection with Fig. 1 may flow into all areas of the cable connection.

Claims

Claims:

1. A spacer for two or more cables or cable cores com prising a star-shaped body of relatively stiff material having radial arms adapted to receive and to hold said cables between said arms at a predetermined distance from each other, characterized in that an annular member of relatively stiff material encompasses said cables, said annular member being designed to be connected to said star-shaped body to form a unit therewith.

2. The spacer of claim 1,wherein said star-shaped body and said annular member are adapted to be connected through a tongue and groove connection.

3. The spacer of claim wherein said star-shaped body and said annular member include connection portions co acting in a snug or tight fit.

4. The spacer of claim 1, wherein one of said star-shaped body and said annular member are formed with an exten sion and the other with a recess to accomodate said extension in a snug and tight fit.

5. The spacer of claim 4, wherein said extension or said recess includes a coaxial projection, preferably in the other a pin adapted to be received by a complementary recess, particularly of a bore in said recess or said extension, respectively.

6. The spacer of claim 5, wherein said pin is conically shaped.

7. The spacer of claim 1, wherein said annular member is splitted into two segments adapted to be plugged to gether such that said annular member may resist a load in circumferential direction.

8. The spacer of claim 1, wherein said segments are inter connected through a tongue and groove connection.

9. The spacer of claim 7 or 8, wherein the free ends of said segments include an extension facing in circum ferential direction and having a recess such that upon an assembly of said annular member with said segments, each of said extensions of one of said segments coacts with a recess of the other of said segments and said extensions coact through a projection engaging an in dentation.

10. The spacer of claim 9, wherein said projection is formed by a coaxial preferably conical pin and said indentation is formed by a corresponding bore.

11. The spacer of claim 1, wherein the inner side of said annular member includes circular-arc recesses for the partial receipt of a cable or a cable core,respectively.

12. The spacer of claim 1 for two or three cables or cable cores, wherein said annular member consists of two identical segments.

13. The spacer of claim 1, wherein said star-shaped body and said annular member are made of flat plastic ma terial.

14. The spacer of claim 1, wherein said star-shaped body and said annular member are formed by injection molding.

15. The spacer of claim 1, wherein said annular member and/ or said star-shaped body is provided with at least one throughbore for the passage of a liquid substance.

16. The spacer of claim I, wherein said annular member and/ or said star-shaped body are dimensioned such that a space is left between them and the cables to allow the passage of a liquid substance.

17. The spacer of claim 1, adapted to be used for a cable connection encompassed by a metallic sleeve, wherein the outer diameter of said annular member being approximately equal to the inner diameter of said sleeve.

18. A spacer as claimed in Claim 1 substantially as herein described with reference to the accompanying drawings.