US3892461A

US3892461A - Load-break connector

Info

Publication number: US3892461A
Application number: US487349A
Authority: US
Inventors: August I Keto
Original assignee: Westinghouse Electric Corp
Current assignee: ABB Inc USA
Priority date: 1974-07-10
Filing date: 1974-07-10
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01

Abstract

Electrical connector having a longitudinal contact, an arcextinguishing rod attached thereto, and an arc-extinguishing sleeve through which the contact and the rod extend. Permanent magnets surround the sleeve and create a magnetic field between the sleeve and the arc-extinguishing rod to force around the rod, any arc contained in the field. A magnetic core member within the arc-extinguishing rod helps provide the desired magnetic field pattern.

Description

United States Patent [191 3,892,461 July 1, 1975 Primary Examiner-Roy Lake Assistant Examiner-Dewalden W. Jones Attorney, Agent, or FirmJ. R. Hanway 57 1 ABSTRACT Electrical connector having a longitudinal contact, an arc-extinguishing rod attached thereto, and an arc-extinguishing sleeve through which the contact and the rod extend. Permanent magnets surround the sleeve and create a magnetic field between the sleeve and the arc-extinguishing rod to force around the rod, any are contained in the field. A magnetic core member within the arc-extinguishing rod helps provide the desired magnetic field pattern.

9 Claims, 5 Drawing Figures SHEET FIGZ PATENTED JUN I975 SHEET FIGS LOAD-BREAK CONNECTOR BACKGROUND OF THE INVENTION l. Field of the Invention:

This invention relates, in general, to electrical apparatus and, more specifically. to load-break connectors containing arc-extinguishers.

2. Description of the Prior Art:

Load-break connectors and fuse assemblies are used in electrical power distribution systems to provide a means for removing apparatus, such as a transformer or a distribution line. from the energizing circuits. Some load-break connectors provide both of the features of switching the load and physically removing the connection between the apparatus or line. A fused load-break connector associated with a power transformer is shown and described in U.S. Pat. No. 3,732.5 l7 which is assigned to the assignee of this invention.

Load-break connectors often have some means contained therein for quenching or extinguishing any arc which generates when a relatively large load current is interrupted. A commonly used arc-extinguishing arrangement is disclosed by U.S. Pat. No. 3,652,975 which is also assigned to the assignee of this invention. This common arrangement uses a contact probe which includes an arc-extinguishing tip attached to the conducting portion of the probe. An arc-extinguishing sleeve is positioned above the contact which engages with the probe. When the probe is withdrawn from the contact, any arc which develops is forced between the sleeve and the arc-extinguishing tip. The length of the arc and the gases generated from the arc-extinguishing material help to extinguish the are.

When this type of load-break connector is used to disconnect very large current levels, eroding of the arcextinguishing materials becomes excessive and channels are formed therebetween which direct the arc. Since the arc tends to be confined to these particular channels, the useful life of the load-break connector is governed largely by the length of time required to erode the arc-extinguishing material enough to prevent its usefulness as an arc-extinguishing feature.

Changing the path of the are through the arcextinguishing material to prevent the formation of a single channel therethrough is desirable to improve the useful operating life of the connector. Therefore, it is desirable. and it is an object of this invention, to provide a load-break connector having apparatus which deters the development of erosion channels within the arcextinguishing members of the connector.

SUMMARY OF THE INVENTION There is disclosed herein a new and useful electrical load-break connector which contains apparatus for reducing the formation of erosion channels in the arcextinguishing materials of the connector. One or more permanent magnets are placed around the outside of the arc-extinguishing sleeve of the connector. The magnets produce a magnetic field between the arcextinguishing sleeve and an arc-extinguishing tip connected to the probe contact of the connector. Any are which develops upon removal of the probe is contained between the probe tip and the sleeve. This are is forced in a lateral direction by the forces associated with the magnetic field. The movement of the are by the magnetic field tends to rotate the are around the probe tip and to prevent the are from maintaining the same path during the continuation of the same arc from maintaining the same path of arcs occurring during successive load-break operations. A member constructed from a magnetic material is positioned within the probe tip to influence the magnetic field. The direction of the magnetic field, and hence the direction of the rotation of the arc, is reversed alternately along the axis of the connector probe.

BRIEF DESCRIPTION OF THE DRAWING Further advantages and uses of this invention will become more apparent when considered in view of the following detailed description and drawing, in which:

FIG. 1 is a partial cross-sectional view of a fused load-break connector constructed according to this invention;

FIG. 2 is a partial cross-sectional view of the loadbreak connector shown in FIG. 1 during partial disengagement',

FIG. 3 is a schematic representation of the magnetic field produced in a load-break connector constructed according to this invention;

FIG. 4 is a schematic representation of the arc path produced in a load-break connector constructed according to this invention; and,

FIG. 5 is a partial cross-sectional view of an elbow load-break connector constructed according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Throughout the following description, similar reference characters refer to similar elements or members in all of the figures of the drawing.

Referring now to the drawing, and to FIG. 1 in particular, there is shown a fused load-break connector 10 constructed according to this invention. The connector 10 is disposed substantially within the enclosure 12 which contains the oil dielectric 14. The connector 10 is attached to the enclosure 12 by the mounting coupling l6 and the threaded adaptor 18. The connector 10 includes two portions which are disengageable or removable from each other. The fixed portion includes the tube 20 which generally extends from the outside to the inside of the enclosure 12. The removable portion includes the fuse 22, the shaft 24, and the eyebolt 26. It can be seen from FIG. 1 that the removable portion of the connector can be pulled from the fixed portion of the connector by pulling on the eyebolt 26. The removable portion of the connector 10 is secured in position when engaged with the fixed portion of the connector 10 by the top cap 28 and the retainer springs 30.

When the connector 10 is engaged as shown in FIG. 1, a direct electrical circuit is provided between the

lugs

32 and 34 which would normally be connected to other circuits within the enclosure 12, such as the windings of a core and coil assembly contained within the enclosure 12 when the apparatus associated with the connector 10 is a transformer. The electrical circuit extends from the lug 32, through the terminal 36, the contact 38, the fuse 22, the conducting shaft 40, the contact 42, the terminal 44, and the lug 34. When the removable portion on the connector 10 is withdrawn from the tube 20 of the fixed portion of the connector 10, the conducting shaft 40 breaks electrical contact with the contact 42, thus opening the direct electrical circuit between the

lugs

32 and 34.

In this specific embodiment of the invention, the conducting shaft is longitudinally shaped and constructed of a good electrically conductive material. The conducting shaft 40 is electrically and mechanically attached to the fuse 22 by the stud 46. The conducting shaft 40 is a component of the probe 48 which is engageable with the probe receiver 50. The probe 48 also includes, in this specific embodiment, a probe tip 51 and a magnetic stud 52. The probe tip 51 has substantially a longitudinal shape and is constructed preferably of an insulating. arcextinguishing material. such as methyl methacrylate filled with dispersed glass fibers, or a material sold commercially under the trademark Delrin. The magnetic stud 52 is positioned within both the conducting shaft 40 and the probe tip 51 to conve niently attach these two members together. The magnetic stud 52 does not necessarily exhibit permanently magnetic properties, but is constructed of a material which influences magnetic flux, such as steel or iron.

The probe receiver includes, in this specific embodiment of the invention, the sleeve 54 which is attached to the terminal 44 and which extends around and above the contact 42. The sleeve 54 is preferably constructed of an insulating, arc-extinguishing material and includes the opening 56 through which the probe 48 may be inserted. The sleeve 54 cooperates with the probe tip 51 to extinguish any are generated between the conducting shaft 40 and the contact 42 upon re movable of the probe 48 from the probe receiver 50. Any are generated would be squeezed or forced between the probe tip 51 and the sleeve 54, thereby the arc tends to be extinguished by the placing of the insulating material in the arc path and by the arc extinguishing gases formed by the reaction of the arcextinguishing materials with the arc.

in this specific embodiment of the invention, the magnets 58 are disposed around the outside of the sleeve 54. The magnets 58 provide a magnetic field between the sleeve 54 and the probe 48 which helps prevent the formation of erosion channels on the surfaces of the sleeve 54 and the probe tip 51. Although the method for attaching the magnets 58 to the sleeve 54 is not shown in detail in FIG. 1, various arrangements may be used without departing from the scope of the invention. For example, the magnets may be positioned between a shoulder on the sleeve 54 and a collar attached to the top of the sleeve 54. The magnets 58 may also be bonded to the sleeve 54 by a suitable adhesive. Depending upon the particular field pattern desired, it may be desirable to provide insulating washers between adjacent magnets 58.

FIG. 2 is an enlarged view of portions of the probe 48 and the probe receiver 50 shown in FIG. 1 is a partially disengaged position. Any arc which would exist between the conducting shaft 40 and the contact 42 would be positioned at the juncture 60 which is defined by the outer surface of the probe tip 51 and the inner surface of the opening 56 in the sleeve 54. Due to the presence of the magnetic field, which is illustrated by the flux lines 62, the path of the arc would be forced in a direction which is perpendicular to the longitudinal axis of the probe tip 51. The result is an elongation of the arc path and a movement of the are around the probe tip 51 for the purpose of preventing the formation of an erosion channel therein.

The magnets 58 illustrated in FIG. 2 have a circular shape with a hexagonal cross-section. The magnets 58 may be constructed of a suitable permanent magnetic material, such as powdered or flaked steel particles secured together by a suitable material and suitably magnitized. The magnetic poles of the magnets 58 are arranged in such a manner that the magnetic field produced thereby provides flux lines 62 which alternate in direction progressively along a dimension parallel to the longitudinal axis of the probe tip 51. The resulting magnetic field is radially oriented, that is, the field is the same around the entire circumference of the probe tip 51 at the same longitudinal position. The orientation of the field changes at different longitudinal positions along the probe tip 51.

FIG. 3 is a schematic representation of the magnetic field produced by a permanent magnet positioned as described herein. The magnet 58' has a south magnetic pole positioned adjacent to the inside face and a north magnetic pole positioned adjacent to the outside face 72 of the magnet 58'. The fields produced thereby are illustrated by the flux lines 74. The magnetic stud 52' functions as a magnetic core for directing the flux lines and to effectively increase the flux density in the region 76 which corresponds to the junction between the probe tip and the sleeve of the connector. The flux lines 74 pass through the region 76 in one direction near the center of the magnet 58, and in the other direction near the outside of the magnetic 58'. When more than one magnet is used in a connector constructed according to this invention, the magnetic poles thereof are similar to those illustrated in FIG. 3. Thus, the flux lines around the outside of the magnets reinforce each other to provide an overall radial magnetic field which alternates in direction along the longitudinal dimension of the connector probe.

FIG. 4 is a schematic representation of a typical arc path which may be produced in a connector constructed according to this invention. The are 78 extends between the conducting shaft 40' and the contact 42', and is positioned on the outer surface of the probe tip 51'. Since the probe tip 51' is closely in contact with the sleeve of the connector, the are 78 is closely confined to the surface of the probe tip 51. Due to the magnetic field represented by the flux lines 62', the path of the are 78 is influenced and the resulting shape may appear as shown in FIG. 4 rather than being substantially straight between the terminating points of the arc. Assuming the same direction of electron flow within the arc, the path of the arc is forced around the probe tip 51 in different directions by the different orientations of the magnetic flux lines 62'.

The amount of rotation of forcing of the arc from a straight path is dependent upon the magnitude of the arc, the magnitude of the magnetic field, and upon other factors such as the speed with which the probe is withdrawn. Although shown in FIG. 4 as having a concentrated path, the are 78 may be dispersed by the action of the magnetic flux lines 62. In such a situation, the arc would tend to develop a partial cylindrical shape, thereby dispersing the energy of the arc over a greater portion of the outer surface of the probe tip 51. Regardless of the form of the deflected are 78, the length thereof is increased, thereby increasing the loadbreak capability of the connector. Also, the position of the arc is changed more so than it would be if it was not tinfluenced by the mangetic flux lines 62', thereby reducing the possibility of forming erosion channels in the arc-extinguishing members of the connector. influenced The ability of the are 78 to change its shape and posi tion during the existence of the arc and as compared to arcs occurring during other load-break intervals, enhances the life of the arc-extinguishing members, As the amount of current through the are changes, the amount of deflection of the are by the magnetic field will change also, thereby preventing the arc to remain in one particular region. In addition, should the arc tend to concentrate in a particular channel of any shape. the concentration of the arc tends to be recognized as an increase in the electron movement through this channel and the resultant force provided by the magnetic flux lines 62' is greater. Thus, any tendency to form a specific channel would result in a greater force being applied to the arc to rotate it out of this channel.

FIG. 5 is a partial cross-sectional view of an elbow type load-break connector constructed according to this inventionv The removable portion of the elbow connector includes the elbow casing 80, the conducting shaft 82. and the probe tip 84 which is connected to the conducting shaft 82 by the magnetic stud 86. The stationary portion of the elbow connector includes the lug 88 which is electrically connected to the contact 90. The contact 90 and the are shaping magnets 92 are contained within the body member 94 which is attached to the enclosure 96. A sleeve 98, constructed of an arc-extinguishing material, is positioned directly above the contact 90 and has an opening 100 through which the shaft 82 and the probe tip 84 extend. The bushing 102 is threadably engaged with the stationary portion of the elbow connector and secures the sleeve 98 within the structure. The magnets 92 may be secured by any suitable means, such as the arrangements described in connection with the embodiment shown in H6. 1. An elbox connector using a magnetic stud to attach the probe tip to the conducting shaft is disclosed in US. Pat. No. 3,617,987.

The operation of the elbow type connector shown in FIG. 5 is substantially the same as the operation of the fused connector shown in FIG. 1. In general, any are positioned between the probe tip 84 and the sleeve 98 is influenced by the magnetic field produced between the magnets 92 and the magnetic stud 86. The are is rotated around the probe tip 84 in such a manner that the formation of erosion channels in the probe tip 84 and the sleeve 98 is substantially reduced. As in the embodiment illustrated in FIG. 1, the magnets provide a magnetic field having a suitable intensity for influencing the path of any are created during a load-break operationv Since numerous changes may be made in the above described apparatus, and since different embodiments of the invention may be made without departing from the spirit thereof, it is intended that all of the matter contained in the foregoing description, or shown in the accompanying drawing, shall be interpreted as illustrative rather than limiting.

I claim as my invention:

1. An electrical load-break connector comprising:

first and second disengageable portions;

A probe attached to said first portion; and,

a probe receiver attached to said second portion;

said probe including a longitudinal conducting member and a longitudinal insulating member which are attached together;

said probe receiver including a contact which is engageable with said longitudinal conducting member to provide an electrical connection, a sleeve constructed of an insulating material and disposed in relation to said contact in such a manner that the probe extends through an opening in said sleeve when said contact is engaged with said probe, and magnetic means for placing a magnetic field between said sleeve and said longitudinal insualting member, said magnetic field influencing the path of any arc which develops between said sleeve and said longitudinal insulating member.

2. The electrical load-break connector of claim 1 wherein a magnetic member is contained within the longitudinal insulating member.

3. The electrical load-break connector of claim I wherein the magnetic field is oriented in a direction which rotates the are around the longitudinal insulating member.

4. The electrical load-break connector of claim 3 wherein the direction of orientation of the magnetic field alternates along the axial dimension of the longitudinal insulating member.

5. The electrical load-break connector of claim 2 wherein the magnetic member extends into the longitudinal conducting member to attach the longitudinal insulating member to the longitudinal conducting member.

6. The electrical load-break connector of claim 1 wherein the magnetic means includes a permanent magnet positioned around the sleeve.

7. The electrical load-break connector of claim 1 wherein the magnetic means includes a substantially circular permanent magnet disposed around the sleeve, said permanent magnet having a magnetic pole of one polarity on the inside thereof and a magnetic pole of opposite polarity on the outside thereof.

8. The electrical load-break connector of claim 1 wherein the sleeve and the longitudinal insulating member are constructed of arc-extinguishing materials.

9. An electrical load-break connector comprising:

first and second disengageable portions;

a longitudinal conducting member having one end thereof attached to said first disengageable portion;

a longitudinal insulating member attached to the other end of said longitudinal conducting member;

a magnetic member extending within said longitudinal conducting and insulating members to provide a magnetic core within said longitudinal insulating member and to connect said longitudinal conducting and insulating members together;

a contact attached to said second disengageable por tion and engageable with said longitudinal conducting member to provide an electrical connection;

a sleeve constructed of an arc-extinguishing material, said sleeve being disposed in relation to said contact in such a manner that said longitudinal insulating member is drawn through an opening in said sleeve when said longitudinal conducting member and said contact are being disengaged; and

a plurality of substantially circular permanent magnets surrounding said sleeve at different axial posi- 7 8 tions, said magnets having magnetic pole locations said magnetic field being oriented in directions whlch develop a magnetic fidd between am Sleeve which cause the arc to rotate in opposite directions and said longitudinal insulating member which tends to rotate. around said longitudinal insulating member, any are which develops between said 5 contact and said longitudinal conducting member alternately along the axis of said longitudinal insulating member.

Claims

1. An electrical load-break connector comprising: first and second disengageable portions; A probe attached to said first portion; and, a probe receiver attached to said second portion; said probe including a longitudinal conducting member and a longitudinal insulating member which are attached together; said probe receiver including a contact which is engageable with said longitudinal conducting member to provide an electrical connection, a sleeve constructed of an insulating material and disposed in relation to said contact in such a manner that the probe extends through an opening in said sleeve when said contact is engaged with said probe, and magnetic means for placing a magnetic field between said sleeve and said longitudinal insualting member, said magnetic field influencing the path of any arc which develops between said sleeve and said longitudinal insulating member.

3. The electrical load-break connector of claim 1 wherein the magnetic field is oriented in a direction which rotates the arc around the longitudinal insulating member.

9. An electrical load-break connector comprising: first and second disengageable portions; a longitudinal conducting member having one end thereof attached to said first disengageable portion; a longitudinal insulating member attached to the other end of said longitudinal conducting member; a magnetic member extending within said longitudinal conducting and insulating members to provide a magnetic core within said longitudinal insulating member and to connect said longitudinal conducting and insulating members together; a contact attached to said second disengageable portion and engageable with said longitudinal conducting member to provide an electrical connection; a sleeve constructed of an arc-extinguishing material, said sleeve being disposed in relation to said contact in such a manner that said longitudinal insulating member is drawn through an opening in said sleeve when said longitudinal conducting member and said contact are being disengaged; and a plurality of substantially circular permanent magnets surrounding said sleeve at different axial positions, said magnets having magnetic pole locations which develop a magnetic field between said sleeve and said longitudinal insulating member which tends to rotate, around said longitudinal insulating member, any arc which develops between said contact and said longitudinal conducting member, said magnetic field being oriented in directions which cause the arc to rotate in opposite directions alternately along the axis of said longitudinal insulating member.