US2988610A - Arc-break device - Google Patents

Description

June 13, 1961 J. BERNATT ARC-BREAK DEVICE 4 Sheets-Sheet 1 Filed June 2, 1958 FlG.I

June 13, 1961 J. BERNATT 2,988,610

ARC-BREAK DEVICE Filed June 2, 1958 r 4 Sheets-Sheet 2 June 13, 1961 J. BERNATT ARC-BREAK DEVICE 4 Sheets-Sheet 4 Filed June 2, 1958 Ivor/mew:

2,988,610 ARC-BREAK DEVICE Joseph Bernatt, Guelph, Ontario, Canada, assignor to James R. Kearney Corporation of Canada Limited, Guelph, Ontario, Canada, a corporation of Canada Filed June 2, 1958, Ser. No. 739,185 2 Claims. (Cl. 200-48) This invention concerns are break devices and more particularly devices used in association with a high voltage switch and designed to establish a temporary by-pass circuit around the switch blades during the opening motion so as to allow the switch blades to be separated from their contacts without drawing an arc. The temporary circuit established by the are break device is then rapidly broken and the arc is drawn between two members of the by-pass circuit so as to avoid injury to the members of the main switching circuit.

The switching of long transmission lines presents many serious problems, one of these being the tendency of switching equipment to draw destructive arcs due to surge currents. This tendency is more pronounced the longer the switched portion of line is. Various types of breaker devices have been proposed in the past, but all of them have been unsatisfactory because of their are drawing properties which impose serious limitations on the length of line with which they can be used. Such devices previously proposed are predominantly of one of the following types: In the usual form, the temporary by-pass circuit is established by a flexible rod in the form of a whip which is engaged by a hook on the contact structure and is bent by the opening of the switch blade until it finally snaps free of the hook. This type of arc breaker has several disadvantages. For one, its thinness renders it rather fragile, particularly under severe icing conditions. A second disadvantage is that by virtue of the very elasticity which produces its beneficial effects, the rod has a tendency to oscillate uncontrollably after release with a resultant detrimental effect on its mechanical and are breaking properties.

Another type of arc break device previously proposed is the type in which a spring loaded nonilexible member attached to the contact structure rests on another nonfiexible member attached to the switch blade structure and rides thereon until the switch blade structure has been raised to an angle where the contact rod becomes disengaged therefrom. The contact rod is then swung back toward the contact structure by its spring. This type of are breaker has proven unsatisfactory due to its tendency to strike the arc toward the contact structure, and also because it requires a separate operation after reclosing the switch to return the arc break device to its operative position.

A third type is so constructed that when the switch blade is opened, an auxiliary contact finger establishes the by-pass circuit. As the opening continues, the movement of the switch blade trips a latch, and a spring withdraws the auxiliary finger into an arc-extinguishing tube. Aside from its high cost, and aside from being subject to malfunctioning due to icing, this type of switch makes difiicult a visual determination whether the auxiliary finger has been re-set, and it is therefore potentially unsafe.

None of the prior art devices of which I am aware could be so designed as to allow the switch blade to be moved almost fully to the open-circuit position, or even rotated more than 60 away from the closed-circuit position before the arc breaker opens. In order to obtain maximum protection against line surges, and consequently in order to allow the maximum line length between switches, it is essential that the switch blade be at least 60 out of closed position before the arc breaker opens.

My invention makes it possible to open the switch blade nite States atent C) to any desired angle, even beyond 135 if necessary, before the arc breaker opens.

I have found that the difiiculties inherent in the prior art structures mentioned above can be eliminated and the effective switchable length of line can be tripled by constructing the arc break device in the form of a heavy spring loaded interrupting member mounted on the switch blade structure and engaged by a hook on the contact structure, whereby positive breaking action is assured and greater breaking speeds can be obtained.

It is therefore an object of our invention to provide an arc break device which is sturdy, positive in its action, and uninfluenced by adverse weather conditions.

The mode of operation of my invention will be'readily apparent from the following description taken in conjunction with the attached drawings, in which:

FIG. 1 is a perspective view of a disconnect switch carrying the arc break device of my invention, as it would appear mounted on a pole;

FIG, 2 is a side elevation of the same;

FIG. 3 is an end view of the structure shown in FIG. 2;

FIG. 4 is a like view showing the switch in the course of the opening movement;

FIG. 5 is a top plan view of the device shown in FIG. 2;

FIG. 6 is a like view showing the switch in the fully closed position;

FIG. 7 is a section along line 77 of FIG. 5; and

FIG. 8 is a section along line 88 of FIG. 7.

In the preferred embodiment of my invention, the arc break device is used in conjunction with a disconnect switch of the type having a fixed base, which is mounted on a pole, cross-arm, or other suitable mounting means. The base supports three insulators, one of which supports the contact structure, and the other two of which support the switch blade and its operating mechanism. The operating mechanism of the switch is so designed that, when the operating lever is rotated in a plane parallel to that of the base, an operating linkage first rotates the switch blade around its axis, and then lifts it away from the contact. Upon closing of the switch, the operation is reversed, with the switch blade being rotated around its axis after it has becomeseated in the contact. The purpose of this construction is to insure proper electrical contact between the switch blade and the contact member. In accordance with my invention, I provide anvarc rod eccentrically mounted on the switch blade itself, and connected to the switch blade through the intermediary of a mounting bell containing a spring which tends to rotate the arc rod in a counter-clockwise direction. The bell, besides constituting a bearing for the arc rod, also protects the spring from the weather. The counter-clockwise movement of the are rod is limited by one or more stop members, also mounted on the switch blade, so as to prevent the arc rod from going beyond a position essentially parallel to the switch blade. Movement of the arc rod is further restricted by a hook member fixedly mounted on the contact structure. When the switch is opened, the rotation of the switch blade first causes the arc rod to enter into firm electrical contact with the hook structure. As the switch blade is raised out of contact with the main contact member, the electrical circuit is maintained through the arc rod and the hook structure.- As'the switch blade is raised further, the eccentricity of the axis of the arc rod mounting bell with respect to the axis of rotation of the switch blade during its opening movement causes the arc rod to be withdrawn from the hook. When the switch blade reaches a predetermined position (approximately from its closed position in our preferred embodiment), the end of the arc rod comes free of the hook, and is rapidly moved away from the hook structure by its own powerful spring. The spring impels the arc rodto move into parallelism with-the switch blade, where the shock-absorbing stop members attached to the switch blade bring the arc rod to rest in the open position. When the switch is closed, the stop members push the arc rod along with the switch blade, and into engagement with the hook structure releasing it only when the switch reaches its fully closed position.

Referring now to the drawings, and particularly to FIG. I, a standard disconnect switch, embodying the arc break device of my invention, is generally shown at 10. The switch is normally mounted in a vertical position on a pair of cross-arms 12, which. in turn, are attached to a pole 14. The position of the switch 10 is normally such that the blade 16 moves upwardly and rearwardly when the switch is opened. The switch is operated by an operating lever 18, which protrudes from the side of the base, and can be engaged by any desired operating tool or mechanism. A clockwise pull on the operating lever 18 will open the switch 10.

In FIGS. 1 through 6, the base of the switch 10 is shown at 20. The base 20 may be formed of any suitable material, such as channel iron. Three insulators, 22, 24, and 26, are mounted on the base 20. The insulators 24 and 26 are fixed, whereas the insulator 22 is rotatably mounted, so that it can be turned by the operating lever 18. A universal linkage, composed of three arms, 28, 30, and 32, connects the top end of insulator 22 to the switch blade 16 in such a manner that, when insulator 22 is turned, the blade 16 undergoes an axial rotary motion, followed by an opening motion around shaft 34. Shaft 34 is fixedly mounted with respect to insulator 24, and forms a part of terminal structure 36. A conventional bridging braid assembly 35, 37 may be used to provide a secure electrical contact between blade 16 and structure 36.

The motion of blade 16 is accomplished in the following manner: At the start of the rotation of insulator 22, and consequently of arm 28 attached thereto, the force exerted on the linkage 28, 30, 32, is in a direction transverse to the length of the base. This results in a force of similar direction at pivot point 38, which, in turn, results in an axial rotation of blade 16, due to the eccentricity of the latter force with respect to the axis of the blade 16. The resultant twist in the linkage is absorbed by arm 30, which has a tubular outer portion 40, and a concentric inner portion 42, rotatable with respect to each other. In the second phase of the motion of insulator 22, and consequently arm 28, the force exerted on pivot point 44 becomes increasingly longitudinal with respect to the base 20. This results in rearward movement of the arm 30, and. due to the eccentricity of pivot point 38 with respect to shaft 34, in an opening motion of blade 16 around shaft 34.

The live terminal 46 of the switch 10 is fixedly mounted on insulator 26, and is electrically connected to a jaw contact 48, which receives the end portion '50 of the blade 16 when the switch 10 is closed. Adjacent the contact 48, the terminal structure 46 also supports a pair of arcing horns 52 and 54. The horn 54 has formed on it a protuberance 56, which projects into the path of the arc rod 58. The other born, 52, is of resilient construction, and serves to urge the arc rod 58 against the horn 54, so as to assure good electrical contact therewith. The are rod 58 is attached, at its lower end, to a rotary bell 60, journaled on a shaft 62 (FIG. 7), and biased for rotation by a spring 64. The shaft 62 is attached to the blade 16 by bracket 66, and a strap 68 insures good electrical connection between the blade 16 and the arcing rod 58.

A stop member 70 is mounted near the upper end of blade 16, and, if desired (particularly in the larger size switches), a second stop member 72 may be provided beyond the upper end of blade 16. The stop members .70 and 72 are rigidly connected together by a brace 74. ,Each of the stop members 70 and'iZ .is provided with a rubber or other shock-absorbing pad 76, against which the arc rod 58 comes to rest.

In operation, the switch 10 is opened in the manner described hereinabove, by a clockwise pull on operating lever 18. As the blade 16 is drawn out of contact with the jaw contact 48 in the latter portion of the motion of operating lever 18, the arc rod 58 is engaged by protuberance 56, and is thereby held in electrical contact with the terminal structure 46, until the blade 16 has been moved through a predetermined are which in our preferred embodiment is at least 75 or During this motion of the blade 16, bell 60 rotates against the bias of spring 64, while, at the same time, are rod 58 moves in a substantially rearward direction until its end 76 comes free of protuberance 56. At that moment, the arc rod 58 becomes free to move upward and rearward, and the force of spring 64 propels it very rapidly in a counterclockwise direction around shaft 62, until arc rod 58 comes to rest against the shock-absorbing pads 76 of the stop members 70 and 72. Due to the sudden and rapid opening motion of arc rod 58, the resulting arc is quickly broken, and any burning which may nevertheless occur is confined to the horn 54 and the tip of the arc rod 58, where it can do no substantial damage.

When the switch is reclosed by moving operating lever 18 forward, the stop members 70 and 72 carry are red 58 right along with blade 16 during the closing motion. Due to the elasticity of horn 52, are rod 58 can be forced through the gap 78 between protuberance 56 and horn 52, so that are rod 58 is once again in operative position when switch blade 16 becomes fully closed.

It will be seen that I have invented a simple, inexpensive, sturdy, safe and effective are breaking device for use with a switch of the type described. It should, however, be kept in mind that my invention is in no way limited to use with a disconnect switch of the type shown. In fact, the arc break device of my invention could readily be used with other types of electrical equipment, in which its features can be put to good advantage. Also, my arc break device need not be mounted on the switch blade, but may for example be eccentrically mounted on shaft 34. Many other modifications are possible within the spirit of my invention, and therefore, I do not desire to be limited by the embodiment described herein, but only by the scope of the following claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. In an electric switch having a fixed contact facing in one direction, a movable contact arm, and a hinged mounting for said contact arm on said switch, spaced from said fixed contact, and located adjacent one end of said contact arm to provide for swinging movement of all portions of said contact arm spaced from said hinge through curved paths toward and away from said fixed contact and for movement of the other end of said contact arm into and out of engagement with said fixed contact, the combination of, an are breaking device comprising a rigid bar in part coextensive with said contact arm and having a tip to which the arc is confined, a hinge connection and an electric connection between one end of said bar and said contact arm and located at a portion of said contact arm adjacent said hinged mounting therefor, which portion swings toward and away from said fixed contact, said hinge connection mounting said bar for swinging movement in a plane parallel to the path of swinging movement of said contact arm, stop means fixed to said movable contact arm adjacent the other end of said contact arm and projecting laterally into overlying relation to the path of swinging movement of the other end of said bar relative to said contact arm, spring means connected between said contact arm and said bar biasing said bar with respect to said contact arm in a direction toward said overlying stop means, a hook means mounted on said switch facing in the opposite direction to said fixed contact, adjacent thereto and electrically connected therewith, and adapted to overlie the other end of said rigid bar adjacent said arcing tip when said switch is closed, yielding means adjacent said hook means and located to guide the other end of said rigid bar around and into said hook means when said rigid bar is propelled by said stop means in the direction of said hook means on movement of said contact arm toward said fixed contact, said yielding means being positioned beside said hook means to engage said n'gid bar simultaneously with said hook means to assure good electric contact with a portion of said bar adjacent said tip, and means to bias said yielding means in a direction with respect to said hook means to prevent disengagement of said rigid bar from within said hook means on opening of said switch until movement of the portion of said contact arm adjacent said hinge connection in a direction away from said fixed contact has produced the other end of said rigid bar from within said hook means.

2. The combination as defined in claim 1 in which a shock absorbing pad is mounted on said contact arm adjacent said stop means, in a position to absorb the recoil from impact of said bar, produced by the force of said spring means thereon, during the movement of said bar by said spring after the end of said bar slides from within said hook means.

References Cited in the file of this patent UNITED STATES PATENTS Re. 22,853 Crabbs Mar. 18, 1947 2,308,026 Rawlins Jan. 12, 1943 2,750,'460 Kast June 12, 1956

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