US3889082A

US3889082A - High voltage contactor

Info

Publication number: US3889082A
Application number: US426063A
Authority: US
Inventors: George L Mcfarland
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1973-12-19
Filing date: 1973-12-19
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10

Abstract

An improved high voltage contactor of the type having arc horns associated with the current-carrying contacts, the arc produced by the interruption of the circuit being supported by the arc horns and there-after being extinguished. The described contactor includes a movable closure mechanism comprising an arm or closure having a first and a second element, the second element being pivoted with respect to the first. A set of arc horns, each of which is associated with a contact tip, are disposed so that there is a gap between them when the contact tips are fully closed. In order to open the contact tips, initial rotation of the first element of the closure causes the second element thereof to tilt with respect to the first, forcing the arc horns into contact before the current-carrying contacts have separated. Further rotation causes the contacts to separate, the arc horns still abutting one another. Still further rotation causes the arc horns to separate, striking an arc therebetween. The arc is generated within an arc extinguishing housing having baffles which lengthen and cool the arc to facilitate its extinguishment.

Description

United States Patent [191 McFarland June 10, 1975 HIGH VOLTAGE CONTACTOR George L. McFarland, Salem, Va.

[73] Assignee: General Electric Company, Salem,

[22] Filed: Dec. 19, 1973 [21] Appl. No.: 426,063

[75] Inventor:

[52] US. Cl. 200/146 R; 200/144 R [51] Int. Cl. H01h 33/12 [58] Field of Search 200/146 R, 144 R [56] References Cited UNITED STATES PATENTS 2,031,516 2/1936 Tritlc ZOO/I46 R 2,318,086 5/1943 Lindstrom 200/l46 R Primary Examiner-Robert S. Macon Attorney, Agent, or FirmW. C. Bernkoft; .l. H. Beusse [57] ABSTRACT An improved high voltage contactor of the type having arc horns associated with the current-carrying contacts, the are produced by the interruption of the circuit being supported by the arc horns and thereafter being extinguished. The described contactor includes a movable closure mechanism comprising an arm or closure having a first and a second element, the second element being pivoted with respect to the first. A set of arc horns, each of which is associated with a contact tip, are disposed so that there is a gap between them when the contact tips are fully closed.

In order to open the contact tips, initial rotation of the first element of the closure causes the second element thereof to tilt with respect to the first, forcing the arc horns into contact before the current-carrying contacts have separated. Further rotation causes the contacts to separate, the arc horns still abutting one another. Still further rotation causes the arc horns to .separate, striking an arc therebetween. The are is generated within an arc extinguishing housing having baffles which lengthen and cool the arc to facilitate its extinguishment.

1 Claim, 4 Drawing Figures PATENTED JUN l 0 I975 SHEET PATENTEDJUH 10 ms 3. a 89,082 SHEET 2 FIG. 4

HIGH VOLTAGE CONTACTOR BACKGROUND OF THE INVENTION The present invention relates to circuit interrupting means and, more particularly, to circuit breakers or contactors designed for use with high currents which cause arcing to occur upon circuit interruption.

Despite the great variety of mechanisms which have been devised to make and break electrical circuits, certain problems have inhered in this activity. One of the most severe problems occurs in the interruption of an electrical circuit carrying high DC currents, for instance in the neighborhood of 1,000 amps or more. When such a circuit is broken by mechanical means, such as by physically separating current-carrying contacts, an arc ordinarily forms between the contacts as they separate in order to maintain current flow. Various approaches to the quenching of this are have been posed from time to time including complex mechanical movements, means for interposing insulating materials between the current-carrying contacts, means for displacing the arc, and means for transferring the arc to other elements remote from the current-carrying contacts which more readily withstand the detrimental effects of the arcing.

In one popular type of contactor arc supporting means, which are often described as arc horns, are associated with the contact tips and oriented so that after contacts open the arc struck therebetween is transferred to the arc horns. However, such a transfer of the are, no matter how rapid, necessarily has some detrimental effects upon the surface of the contact tips and upon their ability to interrupt current flow. Moreover, it is sometimes necessary to provide auxiliary means for causing the arc to travel from the contact tips to the arc horns. Such means may take the form of a blowout coil, an electrical winding and associated magnetic poles which create a strong magnetic field to deflect the arc and cause it to travel further out upon the the arc horns. In some instances, the arc horns are stationary and divergent, with arc suppressing means such as baffles interposed between their extremities. As

- the arc travels out upon the arc horns its length necessarily increases, and due to the baffles a tortuous path is presented all of which serve to aid in cooling and extinguishing the are.

In some designs, the arc horns are formed to move apart, enlarging the length of the arc and facilitating its extinguishment. In still other instances, auxiliary sets of contacts are provided to temporarily bypass the main current-carrying contacts, the auxiliary contacts subsequently opening after the main contacts have opened and striking an arc thereacross. Although this activity is detrimental to the auxiliary contacts, this result is tolerated since they are not relied upon to carry load current. Such contacts, however, need frequent replacement because of the effects of arcing thereupon.

Arc horns which are associated with the contact tips and to which are transferred an arc originating between the tips, may have a much longer life than auxiliary contacts but the requirement that the arc be. initiated at or near the contact tips is extremely detrimental to the tips themselves. Moreover, after the arc has been struck between relatively wide contact tipsit is difficult to thereafter displace the arc into a narrow quenching chute. It will therefore be understood that it would be highly desirable to provide improved contactor means which provide for the supporting of an arc by are supporting elements, without the necessity for initiating an arc between the current-carrying contacts themselves.

It is therefore an-object of the present invention to provide improved circuit interrupting means in which an arc is initiated between arc horns.

It is another object "of the present invention to provide means for the transferring of flow of current to are supporting means before the opening of main currentcarrying contacts.

Still another object is to provide circuit interrupting means in which an arc is initiated in a space which is substantially narrower than the width of currentcarrying contact tips.

SUMMARY OF THE INVENTION Briefly stated, in.accordance with one aspect of the invention, the foregoing aspects are achieved by providing a contactor with closure means which comprise two elements, one of the current-carrying contact tips of the contactor being disposed upon the second of the elements. The first element is pivoted to rotate about a point in order to actuate the contactor. A fulcrum is provided upon the first or the second element, and biasing means disposed adjacent the fulcrum. Upon complete actuation of the contactor, the contact tips are closed with'the are supporting means separated by a predetermined gap. As the contactor is opened and the closure begins to rotate, the second element thereof pivots about the fulcrum and changes its orientation such that the arc supporting means are broughtinto contact with one another. Current then begins todecrease through the main contact tips and increase to encourage the displacement of the are along the are supporting means.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention will be better understood from the following description of the preferred embodiment taken in conjunction with the accompanying drawings in which:

FIG. 1 is a simplified drawing of a high voltage contactor embodying the present invention, in a fully closed position;

FIG. 2 is the contactor of FIG. 1 showing operation of the elements thereof preparatory to the breaking of a circuit; and

FIG. 3 shows a subsequent position of the elements of the contactor immediately prior to the breaking of a circuit.

FIG. 4 is a partial horizontal cross-section of the contactor of the present invention showing the narrowed arc supporting means positioned within the narrow arc chute.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows, in simplified form, elements of a high voltage contactor constructed in accordance with the present invention. A housing 2 is provided with narrow arc suppressing area 3, ordinarily termed an arc chute. A plurality of baffles 4extend from opposite sides of the chute so as to be interleaved with one another and thus create a tortuous path. A first bus 6 is provided with means for attaching a conductor to connect the contactor to oneside of a circuit. Bus 6 is coupled to a first, stationary contact tip 8 and, by means of a winding 10 to a first are supporting means, here shown as are horn 12. Winding 10 comprises the winding of a socalled blowout coil formed around a magnetic core 14. Core 14 extends through winding 10 and connects a pair of pole pieces 15 disposed on either side of arc horn 12 for purposes to be explained hereinafter.

A second bus 16 is provided for connection of the contactor to the other side of the circuit, and flexible lead 18 connects bus 16 to closure means comprising a first element 20 and a second element 22. The first element of the closure member is journaled upon a shaft 24 and pivots thereon in order to effect operation of the contactor. The second element 22 of the closure carriesfa second, movable contact tip 23 which abuts first,stationa'r y contact tip 8 to form the main current carrying path of the contactor. The second element 22 also provided with an are supporting element 26, here 'shown as comprising a suitably-formed extension of the member. In the preferred embodiment, the arc supporting means 12 and 26 are substantially narrower than

contact tips

8 and 23 and are located within the narrow arc chute 3.

The first and second elements of the closure means are coupled together by means of a fulcrum 28 and a biasing means, here shown as the assembled combination of a bolt 30 and a spring 32. A stop 33 is disposed upon first element 20. It is assumed that suitable means will be provided for actuating the closure member and for holding it in an open or a closed position as shown in FIG. 1. Since much means are common knowledge in the art and form no part of the present invention they are not shown, in order to simplify the Figures.

In order to complete a circuit the closure member is forced upwardly by some suitable means, such as a mechanical mechanism 4 or an electromagneticallyactuated armature, until it reaches the position shown. The stationary and

movable contacts

8 and 23 are now held in close abutment, and current flows therethrough.

Arc horns

12 and 26 however, although electrically connected to contact

tips

8 and 23 respectively, are separated by an air gap and therefore are not considered to be in the electrical circuit. Current now flows through bus 6, stationary contact tip 8, movable contact tip 23, and exits from second element 22 of the closure member by way of flexible cable 18 and bus 16.

Referring now to FIG. 2, in order to break the circuit the closure means undergoes rotation in the clockwise sense. When first element 20 has been rotated through a first angle 4) l the bias provided by spring 32 forces the second element 22 to pivot in a counterclockwise direction about the fulcrum 28. The tilting effect thus achieved changes the angular relationship between

contact tips

8 and 23 but does not separate them. Rather, second element 22 rocks upon the stationary contact tip 8 until arc horn 26 is brought into contact with the opposing face of arc horn 12.

It will now be seen that the series combination of blowout coil 10, are horn l2 and are horn 26 form a circuit which is in parallel circuit relationship with

contact tips

8 and 23. At this point, current begins to flow through winding 10 and the abutting arc horns.

FIG. 3 shows the inventive mechanism in a final stage of operation, just before separation of arc horns l2 and 26. Further rotation of the first element 20 of the closure means has proceeded through a second angle (1) 2. So that the second element is about to encounter stop 33, and spring 32 and fulcrum 28 have cooperated to tilt the second element 22 still further with respect to first element 20.

Since a point of contact had previously been established between arc horns' 12 and 26 the further angular displacement of second element 22 with respect to first element 20 of the closure means effects a separation of

contacts

8 and 23. However, since a bypass circuit comprising blowout coil 10 and are horns l2 and 26 has already been established, upon opening of the contacts full current flows through the winding and arc horns. The voltage now arising across the

contact tips

8 and 23 is insufficient to cause a significant arcing to occur. Further, the current now flowing through winding 10 induces magnetic flux in the magnetic core means 14. As stated above core means 14 includes pole pieces 15 disposed upon either side of the arc horns, in

the general vicinity of the point at which the arc horns' contact one another. The direction of the flux traversing the arc horns may be considered to be normal to the plane of the Figures.

It will now be apparent that upon further clockwise movement of first element 20, are

horns

12 and 26 will separate once second element 22 comes to rest across fulcrum 28 and stop 33. Having achieved this position, first and

second elements

20 and 22 will rotate as a unit in a clockwise fashion, rapidly enlarging the gap between

arc horns

12 and 26. As the gap is enlarged the length of the arc supported between the arc horns also increases. Due to the magnetic field supported by core means 14 and according to the wellknown right hand rule, the arc current and the magnetic field will interact. The arc will then be deflected to the right, toward the ends of the arc horns in order to increase still further the length of the arc path. In addition, as it approaches the ends of the arc horns the arc encounters the interleaved baffles 4 of arc chute 3. The cooling effect of the baffles on the arc, and the tortuous path presented thereby, cooperate to force extinguishment of the arc in a manner well known to those skilled in the art.

In prior art devices in which the arc is struck between the contact tips it is necessary to thereafter force the are into a relatively narrow arc chute to quench and extinguish it. With the disclosed apparatus, however, the arc horns may be substantially narrower than the contact tips and advantageously extend within the confines of a narrow arc chute 3. The arc is then initiated within the arc chute, obviating the difficulties inherent in attempting to compress a large arc into a relatively narrow opening.

In closing the contactor the sequence of events described above are repeated, in reverse order. Initial electrical contact is made between

arc horns

12 and 26; however, since there is no arc struck the magnetic field created by blowout coil 10, magnetic core 14 and pole pieces 15 has little effect upon the conduction of current between the arc horns. Further rotation of first element effects a pivoting of second element 22 between the points of contact of the arc horns and ful crum 28, until the main current carrying contact tips touch. A second conductive path is then constituted in parallel with the original path which included the arc horns and blowout coil 10, and current begins to flow through the abutting contact tips. Finally, rotation of first element 20 to its final position effects a further pivoting of second element 22 about fulcrum 28 and the abutting contact tips so as to cause the arc horns l2 and 26 to separate. Since conduction has already been established between the contacts, no arc is drawn between the arc horns upon separation. The circuit breaker is now fully closed, and full load current will flow through the contacts until the circuit breaker is reopened.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of the examples illustrated, and it is therefore contemplated that other modifications or applications will occur to those as skilled in the art. It is accordingly intended that the appended claims shall cover all such modifications and applications as do not depart from the true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A contactor having an arc supporting capaability and comprising:

a housing including arc suppression means comprising an arc chute;

a stationary contact tip for carrying current when saidcontactor is closed;

first arc supporting means electrically connected to said stationary contact tip and disposed within said arc chute for carrying current during the opening and closing of said contactor;

closure means pivotally mounted within said housing;

a second contact tip disposed upon said closure means for making electrical contact with said first contact tip to effect closing of said contactor;

second arc supporting means fixedly connected to said second contact tip and disposed so as to be separated a predetermined distance from said first are supporting means after closing of said circuit breaker and to contact said first are supporting means upon pivoting of said closure means; and

said arc chute and said first and second arc'supporting means having a width substantially less than the width of said contact tips, said second arc supporting means extending into said are chute wherein arcing between said first and second are supporting means is initiated within said arc chute.

Claims

1. A contactor having an arc supporting capaability and comprising: a housing including arc suppression means comprising an arc chute; a stationary contact tip for carrying current when said contactor is closed; first arc supporting means electrically connected to said stationary contact tip and disposed within said arc chute for carrying current during the opening and closing of said contactor; closure means pivotally mounted within said housing; a second contact tip disposed upon said closure means for making electrical contact with said first contact tip to effect closing of said contactor; second arc supporting means fixedly connected to said second contact tip and disposed so as to be separated a predetermined distance from said first arc supporting means after closing of said circuit breaker and to contact said first arc supporting means upon pivoting of said closure means; and said arc chute and said first and second arc supporting means having a width substantially less than the width of said contact tips, said second arc supporting means extending into said arc chute wherein arcing between said first and second arc supporting means is initiated within said arc chute.