US 3721942 A
A high voltage bushing for electrical apparatus, such as transformers. The bushing is hollow and has provisions for receiving either a fuse connector or a solid connector. A lock plate is provided which mounts on the terminal plate of the bushing and prevents withdrawal of the connector while the lock plate is attached to the terminal plate. The lock plate is provided with an eyebolt connector for attaching to the terminal plate. Slots are also provided in the lock plate or connecting one or more high voltage cable leads thereto.
Description (OCR text may contain errors)
United States Patent 1191 Conway 51March 20, 1973 LOCK PLATE FORHIGHVOLTAGE BUSHINGS WITH REMOVABLE CONNECTORS Gerard V. Conway, Pittsfield, Mass. Assignee: General Electric Coinpany Filed: Dec. 3, 1971 Appl. No.: 204,560
U.S. Cl ..339/75 R, 339/125 R, 339/147 R, 339/263 R Int. Cl. ..'..l-l0lr 13/54 Field of Search... ..339/7579, 82,
- References Cited I UNITED STATES PATENTS 8/1932 Schramm .339/126 R 10/1971 Monico et a1 339/2631! 11/1971 Rogers ..339/263 R Primary Examiner-Joseph l-l. McGlynn Attorney-Francis X. Doyle et a1.
[ ABSTRACT A high voltage bushing for electrical-apparatus, such as transformers. The bushing is hollow and has provisions for receiving either a fuse connector or a solid connector. A lock plate is provided which mounts on the terminal plate of the bushing and prevents withdrawal of the connector while the lock plate is attached to the terminal plate. The lock plate is provided with an eyebolt connector for attaching to the terminal plate. Slots are also provided in the lock plate or connecting one or more high voltage cable leads thereto.
7 Claims, 4 Drawing Figures LOCK PLATE FOR HIGH VOLTAGE BUSHINGS WITH REMOVABLE CONNECTORS BACKGROUND OF THE INVENTION This invention relates to high voltage bushings for electrical apparatus and more particularly to a high voltage bushing having a removable connector and provided with a lock plate to prevent premature removal of the connector.
As is well known to those skilled in the electrical apparatus art, such as the transformer art, high voltage bushings are provided on such apparatus so as to enable the electrical power to enter into such apparatus. Often the high voltage bushing is provided with a fuse member which is a portion of the high voltage connector to the high voltage bushing. The fuse is usually removable to provide replacement, if necessary. Other bushings are provided with a solid connector member which may also be removed to provide a visible indica-' tion that power has been disconnected from the .apparatus. This is sometimes necessary in certain utility practice before allowing utility personnel to work on the electrical apparatus.
In most'present day electrical apparatus, the fuse or connector of the bushing must be removed dead, that is, without the line being energized. This is required since the bushing members, especially their connectors, do not have any switching capability. However, even when the secondary load is disconnected from the electrical apparatus, the magnetizing current in such apparatus is usually sufficient to damage the threads of the fuse or solid connector when it is disconnected from the bushing. It is, therefore, considered desirable to disconnect the high voltage leads from the bushing prior to removing the connector member. Obviously, this can be done by an internal switch or by an I external disconnect means. As will be understood, an
external disconnect for a high voltage bushing in the form of a lock plate that prevents removal of the bushing connector prior to removal of the lock plate.
SUMMARY OF THE INVENTION Briefly, in a preferred form, this invention comprises a bushing connected to an electrical apparatus and having terminal contacts on opposite ends of such bushing. One terminal contact has a threaded portion within the bushing and another portion extending through the bushing for connection to the internal portion of the electrical apparatus. The other terminal contact is on the outer end. of the bushing and provides means to connect external power cable to the. bushing. A threaded connector member extends through the bushingand is threaded to the one terminal contact while electrically engaging the other terminal contact. A lock plate or disconnect member is provided having means therein for connecting one or more power cable thereto and provided with attaching means for attaching the lock plate to the other terminal. A lip or extension is provided on the lock plate overlying the outer end of the threaded connector preventing its removal from the bushing.
The invention which is sought to be protected will be particularly pointed out and distinctly claimed in the claims appended hereto. However, it is believed that this invention and the manner in which-its various objects and advantages are obtained as well as other objects and advantages thereof will be better understood by reference to the following detailed description, particularly when considered in the light of the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial sectional view of a high voltage bushing with a removable connector showing the preferred form of lock means secured thereto according to this invention;
FIG. 2 is a front or top view of a bushing of the prior art similar to FIG. 1 without the lock means;
FIG. 3 is an enlarged perspective view of the external end of the bushing of FIG. 1 showing further details of the preferred lock means of this invention; and
FIG. 4 is a perspective view 'of the preferred form of lock means according to this invention.
DESCRIPTION OF PREFERRED EMBODIMENT In the preferred form of this invention, a hollow bushing is attached to the wall of an electrical apparatus and a removable connector extends through the bushing providing an electricalconnection from one end of the bushing to the other. A lock plate is provided on the outer terminal of the bushing preventing removal of the removable connection without removing the lock plate. For a more complete description of this invention,- reference will now be made to the drawing in which like numerals are used to indicate like parts throughout the various views.
Referring first to FIG. 1, a hollow bushing 10 is shown secured to a wall or cover 12 of an electrical apparatus (not'otherwise shown) by bolts 14 extending through a flange 16 on the bushing 10. Obviously, bushing 10 could be bolted, clamped or welded to the wall or cover 12 or otherwise secured thereto in any desired manner. As will be understood, wall 12 is a portion of a container or tank for an electrical apparatus which is usually sealed in such container and provided with a dielectric fluid such as mineral oil for insulation and cooling. Bushing 10 is provided with a contact or terminal 18 which has a threaded portion 20 mounted in the bushing 10 with part 22 extending through bushing 10 as shown. As will be understood, bushing 10 extending into the container of the electrical apparatus is sealed to prevent leakage of fluid from the apparatus or contamination into the apparatus. In a-similar manner, contact 18 which'extends through thebushing 10 at part 22 is also sealed to prevent leakage from the transformer into bushing 10 or any contaminants from bushing 10 into the electrical apparatus. Portion 22 of-contact 18 as shown is normally threaded and provided with nuts 24 for securing the internal lead (not shown) of the electrical apparatus in a manner well understood by those skilled in the electrical apparatus art. The other end of bushing is provided with a terminal plate 26 which is attached to bushing 10 by spring means 28. A connector member 30 is provided which is inserted into bushing 10. Connector 30 has a threaded portion 32 which makes a threaded connection to threaded part 20 of contact 18. The opposite ends of connector 30 is provided with a cap portion 34 and an eye 36. As will be understood by means of eye 36, a linemans hotstick" may be used to insert connector 30 through the opening in terminal plate 26 and thread portion 32 into contact part 20. Cap 34 of connector 30 will cover the opening in terminal 26 and provide electrical contact from terminal 26 through connector 30 to contact 18.
As shown in FIG. 1, connector 30 includes a fuse element 38 which is electrically'and physically connected between threaded end 32 and the cap 34. As will be apparent by means of eye 36 and a hotstick, connector 30 and the included fuse 38 may be removed from bushing 10 to allow replacement of the fuse 38, or to provide a visible disconnect. Of course, if desired, a solid'connector could also be provided in bushing 10 without using a fuse element. As will be readily understood, a solid connector could be removed from bushing 10 in the same manner as connector 30 by use of a hotstick and would provide a desired visible disconnect.
As earlier noted, when removing connector 30, even though the transformer has no secondary load, magnetizing current is present which could damage the threaded connection between contact 20 and 32. To prevent such damage, it is desirable to require removal of the high voltage leads prior to removal of connector 30QFIG. 2 shows the front or top view of bushing 10 as is normal in the prior art. The terminal plate 26 has a slot 40 to receive a terminal connector 42 carrying a high voltage lead 44. As can be seen from FIG. 2, connector 30 can be easily removed-without disturbing in any way the cable lead 44..
To prevent the removal of connector 30 while a cable lead is still connected, a lock plate 46 is provided as can best be seen in FIGS. 3 and 4. Lock plate 46 is essentially a Z-shaped member havinga lock part 48 and a securing and cable carrying part 50, being joined together by angle part 52. The securing part 50 has an opening 54 (FIG. 4) to receive eyebolt connector 56. As can be seen from FIGS. 1 and 3,-'eyebolt connector 56 has a nut 58 and fits into slot 40 on the terminal plate 26. A lug (not shown) is provided on terminal plate 26 at the inner edge of slot 40. As will be understood, the lug holds the nut 58 and allows eyebolt 56 to be tightened, forcing part 50 against terminal plate 26. As is clear from the drawing, lock part '48 is tightened against cap 34 by action of eyebolt 56, thereby locking connector 30 into the bushing 10.
Cable carrying part 50 of lock plate 46 is also provided with a pair of slots 58, 60 for the reception of terminal connectors carrying high voltage leads such as, for example, the terminal connector 42 and lead 44 shown in FIG. 1. As is shown, lugs 62 and 64 are provided on the cable carrying part 50 at the inner edge of slots 58 and 60, respectively, to allow the terminal connectors to be readily connected in the slots. As will be understood, only a single high voltage lead need be secured to lock plate 46. However, often the electrical apparatus using high voltage bushings such as 10 are connected in a loop system whereby continuous electrical energy is provided to all of the electrical apparatus connected in a series circuit. In order to provide continuous electrical energy even when one of the electrical apparatus isout, the lock plate 46 may carry a pair of high voltage leadsin the slots 58 and 60. Then the lock plate 46 could be removed to allow removal of tion is for illustrative purposes only. The scope of the invention is set forth in the appended claims.
What is claimed as new and which it is desired to secure by Letters Patent of the United States is:
l. A lock plate for a high voltage bushing having a terminal plate and a removable connector, said lock plate comprising a Z-shaped member, one end of said member forming a lock means for engaging said removable connector, the other end of said member having means to secure at least one high voltage lead thereto and also including means to secure said lock plate to said terminal plate. 7
2. A lock plate as set forth in claim 1 in which slots are provided in said other end of said member for securing high voltage leads thereto.
3. A lock plate as set forth in claim 2 in which an opening is provided through said other end of said member and an eyebolt connector extends through said opening securing said lock plate to said terminal plate.
4. A lock plate as set forth in claim 1 in which an opening is provided through said other end of said to the enclosure of an electrical apparatus with one portion of said insulator member extending into the enclosure, a first contact in said one portion with a threaded part of said first contact internal of said hollow insulator member, a second contact in the form of a terminal plate secured to the exterior end of said insulator, an opening in said terminal plate, a removable connector extending through said opening into said hollow insulator and having a threaded end threadedly engaging said threaded part of said firstcontact, said removable connector having a cap portion engaging said terminal plate when said threaded end is secured in said threaded part, and a lock plate to prevent removal of said removable connector, said lock plate comprising a Z-shaped member, one part of said Z-shaped member engaging said cap portion of said removable connector, the other part of saidZ-shaped member removably secured to said terminal plate, said other part having means to secure at least one high voltage said Z-shaped member and an eyebolt connector extends through said opening securing said lock plate to said terminal plate.