ENCAPSULATED MAGNETICALLY ACTUATED VACUUM INTERRUPTER WITH INTEGRAL BUSHING CONNECTOR

Abstract: Apparatus (10) for interrupting the flow of current in a power distribution system is disclosed for use with an enclosure containing insulating fluid. The apparatus (10) includes a housing (20) formed from insulating material and having a mounting flange (28) formed along the exterior of the housing (20). The flange (28) is located so that the housing extends away from the mounting side and the upper side of the flange. An electrical current interrupter (16), having electrical input and output ends (16a, 16b), is positioned in the housing (20) so that a portion lies within the portion of the housing extending away from the flange mounting side. An actuator (12) is mechanically connected to the interrupter (16) to provide the mechanical actuation required to interrupt the current flow between the input and output ends of the interrupter. When the flange (28) is attached to the enclosure, the portion of the housing (20) extending away from the flange mounting side extends into the fluid within the enclosure.

Description: ENCAPSULATED MAGNETICALLY ACTUATED VACUUM INTERRUPTER WITH INTEGRAL BUSHING CONNECTOR Field of the Invention The present invention relates to interrupter switch and transformer combinations used in power distribution systems and, more particularly, to the combination of a magnetically actuated vacuum interrupter switch and an oil-filled distribution transformer, the switch being for controlling power to the transformer or the loop connection through the transformer. Background of the Invention When interrupting current to an inductive load, an arc can form between the separating switch contacts. For many years, the practice in the electrical power distribution industry has been the use of loadbreak switching in which contact arcing generated during current interruption physically occurs in an insulating fluid contained within an enclosure. However, the fluids historically in use, such as mineral and silicone oils, are limited in their arc-quenching capabilities. The existence and process of extinguishing the arc causes a breakdown of the insulating medium. In general, when arcing occurs physically within the insulating oil, contamination of the oils results from the formation of by-products. Moreover, gas is generated which acts to raise the system pressure. Venting the enclosure containing insulating oil may be required. Such venting adds to the complexity of the enclosure design. However, liquids are advantageous because of their low cost, ready availability and ease of handling and storage. Unlike oil, there are no by-products resulting from arc in vacuum or an enclosure containing SF 6 gas. Any by-products, formed as a result of arcing in SF 6 gas, tend to recombine into the gas after a short period of cooling. No harmful residues are left in the system. No insulation is lost and no venting is required. Consequently, a need exists for an interrupter that has the insulating characteristics of oil and which does not suffer from disadvantages resulting from the formation of by-products. Summary of the Invention The foregoing disadvantages of fluid degradation during switching are overcome by apparatus for interrupting the flow of current in a power distribution system for use with an enclosure containing insulating fluid. The apparatus includes a housing formed from insulating material and having a mounting flange formed along the exterior of the housing. The flange is located so that the housing extends away from the mounting side and the upper side of the flange. An electrical current interrupter, having electrical input and output ends, is positioned in the housing so that a portion lies within the portion of the housing extending away from the flange mounting side. An actuator is mechanically connected to the interrupter to provide the mechanical actuation required to interrupt the current flow between the input and output ends of the interrupter. When the flange is attached to the enclosure, the portion of the housing extending away from the flange mounting side extends into the fluid within the enclosure. Preferably, the interrupter is either a vacuum interrupter or an interrupter filled with an insulating fluid such as SF 6 gas. It is also preferred for the actuator to be a magnetic actuator. In one embodiment the housing comprises an arm member and a base member, preferably integrally formed. A conductor is connected to the electrical output of the interrupter. It is especially preferred for the base member to be molded around a portion of the conductor. It is also preferred for a current sensor, such as a current transformer, to be positioned proximate the conductor for sensing the current flowing there through. It is also preferred for a flexible conductor to be electrically connected between the output end of the interrupter and the conductor. In such an embodiment, an insulating rod is mechanically interconnected between the actuator and the output end of the interrupter. Brief Description of the Drawings The present invention will be better understood, and its numerous objects and advantages will become apparent by reference to the following detailed description of the invention when taken in conjunction with the following drawings, in which: Fig. 1 is a diagrammatic perspective view of an encapsulated magnetically actuated interrupter with integral bushing connector constructed in accordance with the invention; Fig. 2 is a diagrammatic perspective view of the encapsulated magnetically actuated interrupter with integral bushing connector shown in Fig. 1, from a different angle; Fig. 3 is a diagrammatic perspective view of the encapsulated magnetically actuated interrupter with integral bushing connector shown in Fig. 1, from a different angle; Fig. 4 is a side diagrammatic view of an alternate embodiment of the encapsulated magnetically actuated interrupter with integral bushing connector shown in Fig. 1 ; and Fig. 5 is a diagrammatic section view of an alternate embodiment of the encapsulated magnetically actuated interrupter with integral bushing connector shown in Fig. 1. Detailed Description of the Preferred Embodiments The prior disadvantages of fluid degradation during switching is moderated or nullified in distribution transformers in accordance with the invention by a new system of enclosing small vacuum interruptor switches and their interconnections within larger tanks filled with a conventional insulating and cooling mineral oil. This combination of two insulating systems obtains the maximum benefits of both while minimizing the shortcomings of both for their specific applications. All of the advantages of load switching in a vacuum are retained while the industry-standard bushings and conductors, and the switching modules themselves, are insulated and cooled by the long established benefits and economy of mineral oil liquid. The invention also includes a magnetically driven actuator to drive the vacuum interrupter contacts "open" and "closed." The use of a magnetic drive provides for improved reliability (fewer parts) and the ability to employ remote operation without the use of expensive, motor-driven spring charging mechanisms. Referring to Figs. 1, 2 and 3, an integrated interrupter device 10 is depicted. Device 10 is shown to include a magnetic actuator 12, coupled via insulating rod 14 to vacuum interrupter 16. Magnetic actuator 12 drives the arrangement. To that end, it is noted that the position of rod 14 as determined by the state of actuator 12 will cause interrupter 16 to be in either an opened or closed state. It is noted that no particular interrupter is necessary to practice the invention, however, it is desirable that interrupter 16 include an electrical input end 16a and an electrical output end 16b. When interrupter 16 is mechanically actuated, by operation of magnetic actuator 12 and insulating rod 18, the flow of current between 16a and 16b will either be interrupted or permitted to flow. Typically output end 16b will be an electrically conductive rod that extends into interrupter 16 and is caused by operation of actuator 12 to either make contact or break contact with a second rod forming a portion of electrical input 16a. The opened or closed state of interrupter 16 will, in turn, either permit or interrupt the flow of current from a source (not shown). When current is permitted to flow, the current path is from interrupter 16 through flexible conductor 30 and conductor 19 to bushing connector 22. The flexible current path connector 30, of any suitable contemporary design, is included for permitting current flow in the presence of the axial movement of rod 14, i.e., the flexibility of connector 30 permits its mechanical attachment to rod 14 and its electrical attachment to the conductor (shown in Figs., 1, 2, 4 and 5) extending from actuator 16. The interrupter and actuator are encapsulated in arm 18 and base 20, each being formed from solid dielectric material, preferably urethane, epoxy or other known electrically insulating material. As depicted in Fig. 1, 2 and 3, arm 18 and base 20 are integrally formed, preferably molded. Bushing connector 22, also included within base 20, is preferably constructed similar to those connectors described in ANSI/IEEE Standard 386-1985 (Fig 3 for 200A interface or Fig 10 for 600A interface). It is noted that since rod 14 will exhibit axial movement and since flexible connector 30 will flex laterally, chambers of a size sufficient to permit such movement are formed in arm 18 and base 20. A flange or mounting pad 28 is formed around a portion of base 20 and arm 18. As described below, flange 28 serves to mount device 10 onto another structure such as a container filled with insulating oil. Device 10 is mounted to the sidewall 26 of a transformer by mounting pad 28. In a preferred embodiment, sidewall 26 forms a part of an enclosure containing an insulating fluid such as mineral or silicone oil. Such materials (mineral and silicone oils) are well suited to insulating and cooling purposes. By immersing a portion of interrupter 16 into such fluid, any arcing occurring within the interrupter can be insulated and cooled by the oil. Moreover, either by filling interrupter 16 with an insulating fluid such as SF 6 gas or by forming a vacuum therein, the risk of harmful degradation has been minimized. In this way, the benefits of each medium can be utilized. The single piece or molded construction of base 20 is also shown to include integrated current and voltage sensors, such as current sensor 24, for both line sensing and self-powering (not shown). A loop feeder tap 32 is provided in the molded construction as an extension of conductor 19 for a loop-feed connection through wall 26 and into the transformer. Although the magnetic actuator 12 can be of any particular form, it is desirable to utilize the magnetic actuator disclosed in co-pending patent application 08/794,491 filed February 4, 1997 entitled MOLDED POLE AUTOMATIC CIRCUIT RECLOSER WITH BISTABLE ELECTROMAGNETIC ACTUATOR, incorporated herein by reference. The device 10 also includes connection points for control devices (most likely in the air compartment). Fig. 4 depicts an alternative embodiment of device 10, in which a different magnetic actuator is utilized. In this embodiment, the magnetic actuator is contained within arm 18. In the Fig. 1 embodiment, actuator 12 was mounted to the end of arm 18. Referring now to Fig. 5, yet another embodiment of device 10 is shown. In this embodiment, connector 30a is connected to conducting rods 19a and 19b. A current or voltage sensor 40 is positioned to surround conducting rod 19b to detect the current passing there through. The advantages of this device are numerous: 1) clean interruption by eliminating arching in the oil, 2) reliable operation through the use of magnetic actuators which contain a minimal number of moving parts, 3) flexibility (with the addition of control devices of varying degrees of sophistication the device can perform the duties of a loadbreak switch, resettable fuse, recloser and circuit breaker) and 4) the integration of bushing connector 22 makes the unit compact and eliminates manual joint connections necessary in present day solutions. Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.

Claims: What is claimed is: 1. Apparatus for interrupting the flow of current in a power distribution system, said apparatus adapted for use with an enclosure containing insulating fluid, said apparatus comprising: a housing formed from insulating material; a flange formed along the exterior of said housing, said flange having a mounting side and an upper side and said flange being located on said housing so that said housing extends away from said mounting side and said upper side; an interrupter, having electrical input and output ends for interrupting the flow of current between said input and output ends in response to mechanical actuation, said interrupter being positioned in said housing so that a portion of said interrupter lies within the portion of said housing extending away from said mounting side; and an actuator, mechanically connected to said interrupter to provide said mechanical actuation, wherein when said flange is attached to said enclosure the portion of said housing extending away from said mounting side extends into said enclosure. The apparatus of Claim 1 , wherein said interrupter is a vacuum interrupter. The apparatus of Claim 1, wherein said interrupter is filled with an insulating fluid. The apparatus of Claim 3, wherein said fluid is SF 6 gas. 5. The apparatus of Claim 1 , wherein said actuator is a magnetic actuator. 6. The apparatus of Claim 1, wherein said housing comprises an arm member and a base member. 7. The apparatus of Claim 6, wherein said arm and base members are integrally formed. 8. The apparatus of Claim 1, further comprising a conductor connected to the electrical output of said interrupter and a bushing connector electrically connected to said conductor, wherein said base member is molded around a portion of said conductor and said bushing connector. 9. The apparatus of Claim 8, further comprising a current sensor positioned proximate said conductor for sensing the current flowing there through. 10. The apparatus of Claim 9, wherein said current sensor comprises a current transformer. 11. The apparatus of Claim 9 further comprising a flexible conductor electrically connected between said output end of said interrupter and said conductor. 12. The apparatus of Claim 1, further comprising an insulating rod for mechanically interconnecting said actuator and said interrupter.

Inventors: BOOK WILLIAM J, LEONARDT GUENTER, BOOK, WILLIAM, J., LEONARDT, GUENTER
Applicants: ABB POWER T & D CO, BOOK WILLIAM J, LEONARDT GUENTER, ABB POWER T & D COMPANY INC., BOOK, WILLIAM, J., LEONARDT, GUENTER
Application year: 2000
Main classification: H01H33
IPC codes: H01H1, H01H33