The present invention relates generally to the field of power distribution equipment. More particularly, the invention relates to jacket sleeves used with cable and connectors for power distribution equipment.
Separable connectors are typically employed to interconnect sources of energy, such as electrical distribution network conductors, to localized distribution components, such as switchgears and transformers. These connectors, for example, typically include a bushing insert, which is mounted in the bushing well of the switchgear, and an elbow connector which is releasably connected to the bushing insert on one end and a distribution conductor, such as a high voltage cable, of the network circuit feeding the switchgear. When the elbow is interconnected to the bushing, the switchgear is thus interconnected into the distribution network and thereby energized. Likewise, if the elbow is removed, the switchgear is disconnected from the distribution network and the switchgear is de-energized.
As part of the connection process, the elbow connectors are typically attached to an above ground or underground power cable. In order to attach the cable to the elbow connector, the protective layers of the cable, including the concentric neutrals that provide a path of return for the electrons in an alternating current system, must be removed, or peeled back, from a portion of the cable so that the conductor portion of the cable may be attached to the elbow connector. While a portion of the exposed cable is positioned within the elbow connector, another portion of the exposed cable is left outside of the elbow connector and could be exposed to the elements. The concentric neutrals are particularly at risk and tend to decay rapidly when exposed to moisture. Moisture causes the concentric neutrals to oxidize and corrode. After a certain level of corrosion has built up, the cable needs to be replaced because the return path for the electrons has been permanently disrupted. While the exposed portions of the cable are at risk for decay and damage due to exposure to water and other elements, unexposed portions of the cable are also at risk. For example, water that reaches and contacts the concentric neutrals of the exposed portion of the cable can be wicked away from the point of contact to other areas miles away from the exposed portion of the cable, causing corrosion and failure of the concentric neutrals along long sections of cable.
In order to protect the cable at the connection point with the elbow and other connectors, cable jacket sleeves were created. The cable jacket sleeves had a generally hollow cylindrical shape and came in three primary varieties: pre-molded slide-on, heat shrink, and cold shrinkable. Heat shrink sleeves were placed over the exposed portion of the cable as described below. The lineperson would then use a blowtorch or other heat source to shrink the sleeve around the exposed portion of the cable to create a tighter seal.
Cold shrinkable sleeves are pre-expanded and placed onto a removable core. After the cold shrinkable sleeve is placed over the cable joint, the core is removed and the sleeve shrinks back to its original size, sealing the joint. Pre-molded slide-on sleeves have typically have to be lubricated to reduce the friction created by the tight interference fit required to seal the joint and are manually pushed or pulled onto the cable by a lineperson. Pre-molded slide-on sleeves generally require more steps and force to install, but are simpler and cheaper to manufacture than the other sleeve varieties.
Pre-molded slide-on jacket sleeves required a lineperson to place the seal on the cable prior to attaching the elbow connector. Once the elbow connector was attached to the cable, mastic and/or electrical tape was placed over the exposed portion of the cable and the jacket sleeve had to be pulled back up the cable and across the mastic until it covered the exposed portion of the cable and a portion of the elbow connector. Small tabs were added along both ends of some of the pre-molded slide-on sleeves to assist a lineperson in pulling the sleeve up and down the cable body. When completing the attachment of several connectors to cables, the multiple steps of pulling the sleeve down onto the cable and then pulling it back up the cable once the elbow connector was attached greatly increased the time and effort needed to properly protect the cable.
In order to reduce the time necessary to attach a cable to an elbow connector and properly protect the exposed portions of the cable with a sleeve, and to reduce the overall cost of the sleeve and elbow connector, a conventional combination sleeve and elbow connector has been created. The combination creates an integral jacket sleeve along the portion of the elbow connector to which the cable is attached. The combination is made by molding the elbow connector and the jacket sleeve together, at the same time and from the same material, thereby reducing cost and manufacturing time. In addition, since the jacket sleeve is integrally built into the elbow connection, once a lineperson has attached a cable, he or she need only pull the jacket sleeve in one direction, down over the exposed portion of the cable. In order to assist the lineperson in grasping and pulling the cable, two small tabs have been added to and extend longitudinally from the jacket sleeve.
Unfortunately, the combination jacket sleeve and elbow connector has several drawbacks. First, the exterior of most elbow connectors is made of a conductive or semi-conductive rubber so that the elbow connector can drain off a charge and be at ground potential. The rubber is made conductive by adding carbon black to it. One side effect of adding carbon black to rubber is that it makes the rubber extremely stiff This side effect is beneficial for the elbow connector because it provides added strength to the elbow connector thereby reducing cracking or tearing along the pulling eye and other stress points of the elbow connector when the connector is being attached or detached from the bushing. By making the jacket sleeve from the same material the jacket sleeve is stiff and not pliable. The stiffer jacket sleeve is difficult to get over the exposed portion of the cable, once mastic and/or tape has been applied because the sleeve does not stretch well but still must have an interference fit with the tape or mastic covering the exposed portion of the cable.
Another problem with the combination jacket sleeve and elbow connector is that the small tabs provided along the edge of the jacket sleeve are not sufficient to assist in grasping and pulling the jacket sleeve over the tape and mastic. When connecting cable to the elbow connectors and the elbow connectors to the switchgear or transformer, a lineperson must apply layers of grease to each of the connecting bodies. As a function of the application, a lineperson frequently gets grease on their hands, making it difficult to grasp and hold onto the small tabs provided on the jacket sleeve.
Yet another problem with the combination jacket sleeve and elbow connector is that, the window for error in building up the protective layers of tape and mastic on the exposed portion of the cable is substantially less with the stiffer material being used for the jacket sleeve. Mastic is a gooey adhesive (and in some forms a tape), similar to putty, that bonds to itself and provides a water barrier for the exposed portion of the cable. Unfortunately, mastic tends to become loose and runny under extreme heat and comes off of the cable if it is not held in place. Therefore, electrical tape is typically applied over the mastic in several layers to hold the mastic in place and provide compression. The jacket sleeve generally has an inside diameter that is greater than the cable so that the layer of mastic and tape may be applied and an interference fit with the tape can be created. However, the stiffer the sleeve is, the less a lineperson will be able to get the sleeve over tape that has a diameter that is a little too large.
In view of the foregoing there is a need in the art for a jacket sleeve that may be made integrally with or subsequently affixed to a connector, whereby the jacket sleeve is made of a material that is more pliable than the connector. Furthermore, there is a need in the art for a jacket sleeve that provides an improved method for grasping and pulling the sleeve over the tape, mastic and exposed portions of the cable. Furthermore there is a need in the art for a method of manufacturing a jacket sleeve either integrally or separate from an electrical connector whereby the sleeve is made of a material that is more pliable than the material from which the electrical connector is made.
A jacket sleeve with grippable tabs provides protection to exposed portions of cable that are connected to an electrical connection. The jacket sleeve can be made as part of the electrical connector or may be connected subsequent to its creation through the use of glues or other adhesives. The jacket sleeve can be made of a material that is more pliable than the electrical connector, making it easier for a lineperson to place the sleeve over an exposed portion of cable. The jacket sleeve can also include holes or slots either in the sleeve or in tabs that are attached to the sleeve. A lineperson can place one or more fingers, which may include the thumb, into each hole or slot in order to get a better grip on the sleeve and pull the sleeve over the exposed portion of cable with less slippage and less effort on the part of the lineperson.
For one aspect of the present invention, a jacket sleeve for a cable connector can include an elongated body made of a pliable material, such as rubber. The body can be hollow and have a generally tubular shape. Each end of the tubular body can include openings that create a channel through the body. The tubular body can also include multiple holes or slots. These holes or slots are generally positioned near one of the ends of the housing along the external side of the tubular body. Each hole or slot generally creates an area in the tubular body for grasping and pulling the jacket sleeve onto or off of a cable.
For yet another aspect of the present invention, a jacket sleeve for a cable connector can include an elongated housing made of a pliable material, such as rubber. The housing can include a hollow body having a generally tubular shape. Each end of the tubular body can include openings that create a channel through the body. The jacket sleeve can also include two or more pull tabs attached to one end of the tubular body. Each tab can include a hole or slot. Each hole or slot is generally positioned along the external side of the tab. Each hole or slot generally presents an area in the tab for grasping and pulling the jacket sleeve onto or off of a cable.
For still another aspect of the present invention, an electrical connector can include a connector body made up of an insulated housing and a channel through at least a portion of the insulated housing. The channel defines an area for receiving an electrical cable. The connector body can also include a opening along one end of the channel that acts as the entry point for the electrical cable into the connector body. The electrical connector can further include an elongated jacket sleeve made of a pliable material, such as an EPDM (ethylene-propylene-dienemonomer) or silicone elastomer. The sleeve can include a hollow body having a generally tubular shape. Each end of the tubular body can include openings that create a channel through the body. The jacket sleeve can also include two or more pull tabs attached to one end of the tubular body. Each tab can include a hole or slot. Each hole or slot is generally positioned along the external side of the tab. Each hole or slot generally presents an area in the tab for grasping and pulling the jacket sleeve onto or off of a cable. Another end of the jacket sleeve can be coupled to the insulated housing of the connector body at a point near one end of the channel.
For yet another aspect of the present invention, a method of making an electrical connector can include molding a connector body having the features described hereinabove. A jacket sleeve having features described hereinabove can be molded. One end of the jacket sleeve can then be coupled to the insulated housing of the connector body along an area adjacent to the opening for the first end of the channel. The coupling can be achieved using an adhesive.
For another aspect of the present invention, a method of making an electrical connector can include molding a connector body having the features described hereinabove. The connector body may be allowed to cure and can then be placed into a second mold. In the second mold, a jacket sleeve having the features described hereinabove can be overmolded onto the connector body. The overmolded material cures and cross-links with the connector body creating a strong, permanent chemical bond.
For still another aspect of the present invention, a method of making an electrical connector can include preparing a mold for the creation of the electrical connector and jacket sleeve combination. A first material can be injected into a first portion of the mold. A second material can simultaneously be injected into a second portion of the mold. The first portion of the mold generally has the shape of the connector body described herein and will be substantially filled with the first material. The second portion of the mold generally has the shape of the jacket sleeve and will be substantially filled with the second material.
For a more complete understanding of the exemplary embodiments of the present invention and the advantages thereof, reference is now made to the following description in conjunction with the accompanying drawings in which:
The present invention is directed to a jacket sleeve for an electrical connector and methods for making the same. Exemplary embodiments of the invention can be more readily understood by reference to the accompanying figures.
Exemplary embodiments of the present invention include a jacket sleeve for receiving therethrough and protecting a high voltage cable in a power distribution environment. However, it should be apparent that there could be many different ways of implementing the invention in an electrical environment, and the invention should not be construed as limited to a high voltage environment or any one set of features or methods described herein. The inventive functionality of the jacket sleeve with grippable tabs will be explained in more detail in the following description and is disclosed in conjunction with the remaining figures.
Referring now to the drawings in which like numerals represent like elements throughout the several figures, aspects of the present invention will be described.
The loadbreak connector 10 generally includes a bushing 14 and an elbow connector 12, which is integrally connectable over the bushing 14. The elbow connector 12 includes an insulated conductor receiving portion 16 which can receive a high voltage conductor or cable 26 therein, and a substantially right-angled probe retainer portion 18. The exterior conductive surface of the elbow connector 12 is interconnected to ground 6 through a ground strap 4 interconnected to a grounding aperture, or hole, 54 in a grounding tab 52. This ensures that the outer surface of the elbow connector 12 remains at ground potential. The bushing 14 is installed through a hole, or aperture, 7 in the wall of the switchgear enclosure wall 9 and is electrically connected to the switchgear 8. The bushing 14 includes an internal shank end 20 and a probe receiving portion 22 forming opposite ends of the bushing 14 separated by a flange 72. The probe receiving portion 22 of the bushing 14 is received within a probe retainer portion 18 of the elbow connector 12 upon interconnection thereof.
While the elbow connector 12 is presented as having a representative elbow-like design in
An arc follower 220 constructed from ablative material extends from an opposite end of the probe 214. In one example, the arc follower 220 may be constructed from acetal co-polymer resin loaded with finely divided melamine. The ablative material may be injection molded on an epoxy bonded glass fiber reinforcing pin 222. A recess 224 is provided at the junction between the probe 214 and the arc follower 220. An aperture (not shown) is provided through the exposed end of the probe 214 for the purpose of assembly.
The elbow connector 12 may further include capacitive test aperture 226. The test aperture 226 provides a shielded, hotstick-operable means to determine circuit condition when used with high impedance voltage sensing devices known to those of ordinary skill in the art (not shown). The test aperture 226 can include a cap (not shown) that is capable of being snapped into and covering the aperture 226 and thereby preventing access to the aperture 226 from a position external to the elbow connector 12. The elbow connector 12 may further include a semi-conductive insert 228, positioned such that it surrounds a portion of the conductor contact 216 and the cup-shaped recess 218 substantially near the point of interaction between the conductor contact 216 and the probe 214. The semi-conductive insert 228 controls electrical stress within the elbow connector 12. In one exemplary embodiment, the semi-conductive insert 228 is made of a molded peroxide cured EPDM.
The elbow connector 12 further includes a pulling eye 230. The pulling eye 230 is positioned substantially in line with the longitudinal axis of the probe 214 and opposite the opening of the cup-shaped recess 218. The pulling eye 230 provides a point of attachment for a hotstick or other device to engage or disengage the elbow connector 12 from the switchgear 8 or other electrical device. In one exemplary embodiment, the pulling eye 230 is composed of stainless steel, however other metallic and non-metallic elements known to those or ordinary skill in the art may be employed in place of stainless steel. The external surface of the pulling eye 230 is typically surrounded by the conductive shield layer 212.
The elbow connector 12 can further include a compression connector 232 coupled to and positioned along and affixed to one end of the conductor contact 216. The opposing end of the compression connector 232 is capable of slidably receiving and being affixed to a cable 26, to provide electrical communication and transmission between the cable 26 and the conductor contact 216. Those of ordinary skill in the art will recognize that the present invention is not limited to the use of compression connectors 232 within the elbow connector 12 and that other types of cable connectors known to those of ordinary skill in the art may be used within the scope of the invention. The elbow connector 12 further includes a grounding eye 234 that can be molded into or affixed to the semi-conductive shield 212 along the exterior of the elbow connector 12. The grounding eye 234 is capable of receiving and being connected to a drain wire (not shown), typically made of copper or other metallic material, to ensure deadfront construction.
The elbow connector 12 also includes a cable receiving aperture 236 positioned along one end of the conductor contact 216. In one exemplary embodiment, the aperture 236 has a substantially cylindrical shape and has an inner diameter that is dependent on the size of the cable 26 that the aperture 236 is intended to receive. One end of the cable 26 may be slidably inserted into the aperture 236 until it abuts and is connected to the compression connector 232.
The elbow connector 12 is operable or matable to a female connector during “loadmake”, “loadbreak”, and “fault closure” conditions. Loadmake conditions occur when one of the contact elements, such as the probe 214, is energized and the other contact element, such as a female contact element (not shown), is engaged with a normal load. An arc of moderate intensity is struck between the contact elements as they approach one another and until joinder under loadmake conditions. Loadbreak conditions occur when the mated probe 214 and female contact element (not shown) are separated when energized and supplying power to a normal load. Moderate intensity arcing again occurs between the contact elements from the point of separation thereof until they are sufficiently removed from one another. Fault closure conditions occur when the probe 214 and female contact element are mated, with one of them being energized and the other being engaged with a load having a fault, such as a short circuit condition. Substantial arcing occurs between the contact elements in fault closure conditions as the contact elements approach one another and are joined. In accordance with known types of loadbreak connectors, expanding gas is employed to accelerate the female contact in the direction of the probe 214 as the elbow connector 12 and female connector are engaged, thus minimizing arcing time and hazardous conditions.
The jacket sleeve body 302, neck 304 and tabs 306, 308 can be made of EPDM, rubber, silicone or other suitable materials known to those of ordinary skill in the art. The jacket sleeve body 302, neck 304, and pull tabs 306, 308 are generally made of a material that is more pliable than the semiconductive shield 212 of the elbow connector 12. By making the jacket sleeve 300 from a material that is more pliable than the semiconductive shield 212, it will be easier to stretch the jacket sleeve 300 over the exposed portion of the cable after mastic and tape have been applied. In certain exemplary embodiments, the jacket sleeve body 302, neck 304 and tabs 306, 308 are made of EPDM. In another exemplary embodiment, the semiconductive shield 212, jacket sleeve body 302, neck 304, and pull tabs 306 are made of different types of rubber, with the rubber used in the semiconductive shield 212 having a higher durometer than the rubber used in the jacket sleeve body 302, neck 304 and pull tabs 306, 308. In an alternative embodiment, the semiconductive shield 212, the jacket sleeve body 302, neck 304 and tabs 306, 308 are all made from a semiconductive material, wherein the semiconductive material used to make the jacket sleeve body 302, neck 304 and pull tabs 306, 308 has a reduced amount of carbon black or an increased amount of oil such that the material has an increased pliability over the material used to make the semiconductive shield 212 for the elbow connector 12.
The attachment neck 304 is attached or forms an integral part of the jacket sleeve body 302 and, in certain exemplary embodiments, has an inner diameter that is smaller than the inner diameter of the jacket sleeve body 302. In embodiments where the neck 304 is attached to the jacket sleeve body 302, known attachment means may be used, including, but not limited to adhesives and glue. In certain exemplary embodiments, the outer diameter of the neck 304 is also smaller than the outer diameter of the jacket sleeve body 302. The inner diameter of the neck 304 is typically larger than the outer diameter of the elbow connector 12 in an area substantially adjacent to the cable receiving aperture 236. Alternatively, the neck 304 may have the same inner and outer diameter as the jacket sleeve body 302 such that the neck 304 and jacket sleeve body 302 are one and the same. The neck 304 is typically positioned over the elbow connector 12 in an area substantially adjacent to the cable receiving aperture 236.
The pull tabs 306, 308 are integrally connected to the jacket sleeve body 302 along the end of the jacket sleeve body 302 opposite the neck 304. The tabs 306, 308 are generally made of the same material as the neck 304 and the jacket sleeve body 302. While the exemplary embodiment of
Each tab 306, 308 includes an operating eye, slot or hole, such as slots 310, 312. The slots 310, 312, can have many different types of shapes and sizes known to those of ordinary skill in the art including, but not limited to oval, circular, diamond, quadrilateral, square, rectangular, and half-moon-shaped, just to name a few. In certain exemplary embodiments, the size of the slot 310, 312 is sufficient to accommodate the thumb of an average man. A reinforcement strip 316 can be included along all or a portion of the edge of each slot 310, 312. The reinforcement strip 316 is typically an increased thickness of the material making up the tab 306, 308 and provides increased strength and durability along the edges of the slot 310, 312.
In other embodiments, the tabs 306, 308 can be replaced with an extension of the jacket sleeve body 302 having a circular cross-section (not shown). One or more slots 310, 312 may be cut out, or molded, into the jacket sleeve body 302 and have a shape and size similar to that described hereinabove. The jacket sleeve 300 may also include one or more ribs 314. Although only shown around tab 306, ribs may also be positioned along the neck 304 and/or jacket sleeve body 302. Each rib 314 typically extends along the longitudinal axis of the exterior of the neck 304, jacket sleeve body 302, and/or tabs 306, 308. However, the ribs 314 may also extend circumferentially, diagonally or in any other pattern or combination of patterns along the jacket sleeve 300. Each rib 314 is typically made of the same material as the jacket sleeve body and has a thickness that is greater than the body of the portion of the jacket sleeve the rib 314 is positioned along. The ribs 314 are designed to provide improved strength characteristics for the portion of the jacket sleeve along which they extend.
The jacket sleeve 300 can be integral to or created separately from the body of the elbow connector 12. For example, the jacket sleeve 300 and the elbow connector 12 can be molded separately using known molding methods and the jacket sleeve 300 is affixed to the exterior of the elbow connector 12 near the cable receiving aperture 236 via glue or another known adhesive. As another example, the molded elbow connector 12 can be placed into a second mold so that the jacket sleeve 300 can be overmolded onto the elbow connector 12, thereby bonding the jacket sleeve 300 to the elbow connector 12.
As still another example, the elbow connector 12 and the jacket sleeve 300 can be created using co-injection molding. Using co-injection molding, the elbow connector 12 and the jacket sleeve 300 can be made integral to one another at the same time using a single mold. Using co-injection molding technology, which is known in the art, a semiconductive material having a higher durometer can be injected into one side of the mold and a softer, more pliable material having a lower durometer can be injected into the other side of the mold. The two materials would meet substantially near the neck 302 of the jacket sleeve 300, wherein the semiconductive material would make up a substantial portion of the elbow connector 12 and the more pliable material would make up a substantial portion of the jacket sleeve 300.
To limit the amount of water and other elements that may come into contact with the inner layers of the cable 26, the jacket sleeve 300 and other materials are placed around the exposed portions of the cable 26 along the jacket body 302 portion of the jacket sleeve 300. For example, mastic 604, or another form of gum, resin, or adhesive, may be placed on the exposed portions of the cable 26, including over the concentric neutrals 602. The objective of the mastic 604 is to prevent water or other elements or dirt from reaching the concentric neutrals 602 and corroding them or other portions of the cable 26.
Electrical tape 606 or other forms of tape may be wrapped around the mastic 604 and the exposed portions of the cable 26. The electrical tape 606 may help to maintain the general shape of the mastic 604 and keep the mastic 604 in contact with the exposed portions of the cable 26. Once the tape 606 and mastic 604 are in place, the jacket sleeve 300, which is positioned along the cable receiving aperture 236 of the elbow connector 12 along the semiconductive layer 212, may be grasped at the slots 308, 310 and pulled toward the portion of the cable 26 covered with mastic 604 and tape 606 until the jacket sleeve 300 completely covers the mastic 604 and taped 606 portion of the cable 26 and the jacket sleeve 300 has an interference fit with the taped portion of the cable 26 along the jacket body 302. In certain embodiments, the objective of the jacket sleeve 300 is not to create a water-tight or element-tight seal but is instead to hold or substantially hold the mastic 604 and tape 606 in position over the exposed portion of the cable 26.
In certain embodiments, the method of connecting a cable 26 to the elbow connector 12 and protecting the exposed portion of the cable 26 with a jacket sleeve 300 begins by wrapping a strip of mastic 604 around the exterior cable jacket. The cable jacket can then be stripped off of a portion of the cable 26. The exposed concentric neutrals 602 of the cable 26 are bent back along the length of the cable 26 and over the mastic 604. The concentric neutrals 602 are pressed into the mastic 604 and additional mastic 604 is wrapped around the insulation shield, cable jacket, and concentric neutrals embedded in the first layer of mastic 604. Additional mastic 604 or electrical tape 606 may be added on top of the second layer of mastic 604 if necessary to build up the diameter of the protected area so that the jacket sleeve 300 will make an interference fit along the jacket body 302 with the tape 606 that is subsequently wrapped around the mastic 604.
Next, the insulation and the insulation shield are removed from the exposed end of the cable 26. A compression connector 232 is connected to the conductor 608 of the cable 26 and rotated to spread the inhibitor of the compression connector 232. The cable 26 and cable receiving aperture 236 are lubricated and the elbow connector 12 is slid down upon the conductor 608 of the cable 26. A copper wire or other equivalent is attached to the grounding eye 234. The lineperson then grabs the jacket sleeve 300 by placing one or more fingers through each of the slots 310, 312. The lineperson pulls the jacket sleeve 300 in the direction of the mastic covered cable 26 to a point such that the jacket sleeve body 302 covers the exposed portion of the cable 26 outside of the elbow connector 12. The copper wire is attached to ground 6 and the elbow connector 12 is attached to the switchgear 8 or transformer.
In conclusion, the present invention is directed to a jacket sleeve having pull tabs for use with elbow connectors and other electrical products in which exposed wire or cable must be protected. In addition, the present invention is directed to methods of making and using a jacket sleeve with pull tabs. The foregoing description relates to certain exemplary embodiments of the present invention; it will be evident to those of ordinary skill in the art that various modifications and changes may be made thereto without departing from the spirit and the scope of the present invention as set forth in the appended claims and equivalents thereof.
This patent application is a divisional of U.S. patent application Ser. No. 11/809,508, entitled “Jacket Sleeve With Grippable Tabs For A Cable Connector,” filed Jun. 1, 2007, the complete disclosure of which is hereby fully incorporated herein by reference.
Number | Date | Country | |
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Parent | 11809508 | Jun 2007 | US |
Child | 12646206 | US |