US3235697A

US3235697A - Contact construction for fault closing switch

Info

Publication number: US3235697A
Application number: US287309A
Authority: US
Inventors: Sigurd O Rodeseike
Original assignee: ITE Circuit Breaker Co
Current assignee: ABB Inc USA; ITE Circuit Breaker Co
Priority date: 1963-06-12
Filing date: 1963-06-12
Publication date: 1966-02-15
Anticipated expiration: 1983-02-15
Also published as: GB1044617A

Description

Feb. 15, 1966 s. o. RODESEIKE 3,235,697

CONTACT CONSTRUCTION FOR FAULT CLOSING SWITCH Filed June 12, 1963 55; Six.

3,235,697 CONTACT CONSTRUCTION FOR FAULT CLDSING SWITCH Sigurd 0. Rodeseike, Greensburg, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed June 12, 1963, Ser. No. 287,309 6 Claims. (Cl. 200-166) The instant invention relates to load interrupter switches and more particularly to a novel stationary contact structure for use in load interrupter switches which are so designed as to permit switch closings for high currents of magnitudes which are beyond the capability of load interrupter stationary contact structures presently in use.

Power distribution systems presently in use have protective means in the form of circuit breakers for the purpose of automatically isolating a section, or sections of distribution system upon the occurrence of overload or severe fault current conditions occurring in that section, or those sections of the system. After the tripping operation is performed, means are provided to further isolate that portion or portions of the distribution system which means normally in the form of load interrupting switches, which may either be manually or automatically operated to the open circuit condition to isolate a section of the distribution network from the energy source during a period in which the fault condition may be corrected and cleared. While such load interrupter switches are normally designed so as to isolate a portion or portions of the network after tripping automatic tripping of the circuit breaker, it is nevertheless desirable to provide load interrupter switches with the capability of being rapidly operated to both the open and closed position, since the possibility may exist that the closing and/ or opening operation may be performed, accidentally or otherwise, during the time in which the circuit connected to the load interrupter switch is energized.

During the closing, as Well as the opening operation and when the cooperating contacts are only a slight distance apart from one another, the breakdown voltage of the atmosphere is exceeded by the energy in the line and an arcing condition occurs. During the opening operation, this arcing condition can cause a rapid deterioration of the contact structure and is therefore an undesirable characteristic. In addition thereto, so long as an arcing current is present, the circuit is not interrupted until such arcing current is extinguished.

During the closing operation and when the load interrupter switch closes upon an energized circuit a like arcing condition occurs, setting up an arc current having a curved path which due to its curvature sets up a magnetic field which tends to urge the contact source towards separation, which phenomenon is known as a blow-open effect. Thus, when large currents are present in the network, it becomes extremely difficult, if not impossible, to close a load interrupter switch into an energized line.

The contact structure of the instant invention is designed in such a way as to permit closing of the load interrupter switch into an energized line without the necessity of providing any mechanical, magnetic, or other type locks to achieve such a closing operation. In addition thereto, contact structure of the instant invention has been proven successful in permitting a closing operation into energized lines carrying currents exceeding 60,000 asymmetrical amps, while presently employed contact structures have been capable of closing into energized circuits only up to 18,000 to 20,000 asymmetrical amp magnitudes, thus the instant invention provides a contact structure configuration having at least three times greater current carrying capacity into which the load interrupter switch may be closed.

3,235,097 Patented Feb. 15, 1966 The instant invention is comprised of a stationary contact structure having main contacts which are positioned so as to be offset in the direction of the hinge side of the load interrupter switch in order to provide a current path which is bent in the direction of the load interrupter switch main blade. In place of employing the normal four line conventional contacts positioned two on each side of the stationary contact structure, the instant invention comprises only two line contacts, one being on each side of the stationary contact structure and having a mass concentration positioned behind the two line contacts, thus the arcing contact is completely eliminated in order to secure the widest possible angle formed between the load interrupter switch blade and the stationary contact structure at the instant of initial engagement therebetween. It has been found that using such a contact structure arrangement with a standard knife blade construction, capacity of the, switch is so designed and has been increased in the area of 60,000 asymmetrical amperes as opposed to 18,000 to 20,000 asymmetrical ampere capacity of load interrupter switches presently in use. The higher rating is furthermore achieved without additional magnetic locks, mechanical locks, or electrical locks of any sort in order to assist engagement at such high ratings.

It is therefore one object of the instant invention to provide a stationary contact structure for load interrupter swiches and the like, which structure has a novel configuration enabling load interrupter switch blades to be closed in to energized lines, having magnitudes of extremely high ratings.

Another object of the instant invention is to provide a stationary contact structure for use in load interrupter switches and the like, which is so designed as to widen the angle between the stationary contacts and the blade at the instant of initial engagement therebetween in order to minimize any blow open forces set up between the stationary contact and the moving blade.

Still another object of the instant invention is to provide a stationary contact structure for use in load interrupter switches and the like which is so designed as to offset the two line contacts employed in the stationary contact structure in the direction of the blade hinge in order to substantially increase the fault-current capacity of load interrupter switches employing such stationary contact structures.

Another object of the instant invention is to provide a stationary contact structure for use in load interrupter switches and the like which is so designed as to provide a contact structure which is offset in the direction of the load interrupter switch blade and which further has a heavy mass concentration behind the stationary contacts to provide for maximum current carrying capacity of the contacts and the main blade at the instant of engagement therebetween.

These and other objects of the instant invention will become apparent when reading the accompanying description and drawings in which: FIGURES 1a, lb and 1c are top-side and end views respectively, of a stationary contact structure designed in accordance with the principles of the instant invention.

FIGURES 2a and 2b are top and side views respectively, of a load. interrupter switch employing the stationary contact structure of FIGURES 1a1c.

FIGURE 3 is a side view of a contact structure of the prior art.

Referring now to the drawings, FIGURES la-lc show a jaw casting for use in load interrupter switches and the like, having a terminal portion 101 which is substantially flat and which is provided with a plurality of apertures 102 adapted to receive suitable fastening means (not shown) for rigidly securing the terminal portion 101 into a series relationship with the circuit being protected (not shown). The terminal portion 101 is offset at 103 and forms the base portion 104 of the contact structure. Contact portion 105 projects upwardly from the base portion 104 and substantially forms a right angle with the base portion. Contact portion 105 is provided with first and

second contact surfaces

106 and 107 which engage the main blade in a manner to be more fully described.

The base portion 104 is provided with

suitable apertures

108 and 109 for receiving suitable fastening means (not shown) to secure the jaw structure 100 to the insulating post upon which it is positioned, as well as the arc extinguishing chute for the auxiliary blade of the load interrupter switch which will be more fully described. With reference to FIGURES la and 112, base portion 104 is further provided with an aperture 110 in its under-side, the center of aperture 110 being located at 111. The phantom line 112 which is located at the center of the

contact surfaces

106 and 107 is offset from the center 111 of aperture 110 which center 111 also represents the longitudinal axis of the insulating post upon which the jaw structure 100 is positioned. This offset arrangement acts to increase the angle formed between the

main contacts

106 and 107 so as to minimize the blow open effect which will be more fully described. The contact portion 105 is provided with a rib 113 which communicates with the base portion 104 and

contacts

106 and 107 in order to provide a direct current path between the upper ends of

contacts

106 and 107 and the terminal portion 101. The purpose for this heavy mass concentration in the form of rib 113 will be more fully described.

Referring now to FIGURES 2a and 2b, a load interrupter switch 200 is shown therein which is comprised of a pair of

insulating posts

201 and 202 which may be mounted by suitable fastening means (not shown) upon a supporting base plate 203, which may be a cubicle side wall or a horizontally aligned plate since the load interrupter switch assembly 200 may be aligned either vertically or horizontally, depending only upon the needs of the user. A first terminal member 204 is secured upon post 202 by suitable fastening means (not shown) and is provided with a plurality of apertures 205 for receiving fastening means to connect terminal 204 into the electrical circuit in which it is to be used. Terminal member 204 is provided with a projecting portion 206 having a suitable aperture (not shown) for receiving a pin 207 which pivotally links a main blade assembly 208 to projecting portion 206.

The main blade assembly 208 is comprised of first and second blade members 208a and 208b pivotally linked to projecting portion 206 by pin means 207. The blade assembly 208 is further provided with a projecting pin 209, secured thereto and provided to pivotally couple an auxiliary blade 210 thereto. A spacer means 211 is provided on pin 209 to properly position and locate the auxiliary blade 210 relative to the main blades 203a and 20811. The left-hand end of blades 208a and 2081) are further fastened together by a suitable fastening means 212 located near the left-hand ends of blades 208a and 208b. The main blades 208a and 208b when in the closed position, as shown in FIGURES 2a and 2b have their inner surfaces engaged in the

contacts surfaces

106 and 107 of the jaw structure 100. The jaw structure 100 is mounted and secured upon the insulator post 201 by suitable fastening means and is provided with the apertures 102 (see FIGURE 1a) for securement to the circuit in which the load interrupter switch assembly 200 is to be used. Also, mounted upon the insulator post 201 is a bracket 213 which supports an arc extinguishing chute 214 which receives the auxiliary blade 210. A detailed description of the arrangement and operation of load interrupter switch 200 will be omitted here for purposes of clarity. The detailed description is fully set forth in copending U.S. application, Serial No. 216,161

d entitled Low Brake Interrupter Switch filed August 10, 1962, now Patent No. 3,178,543 by Roy H. Albright et al. and assigned to the assignee of the instant invention.

For the purpose of understanding the load interrupter switch in FIGURES 2a and 2b, however, it is sutficient to understand that during the opening operation the main blade assembly, which is comprised of blade members 208a and 208b, pivots clockwise about pin 207 so as to disengage from the

contacts

106 and 107 of the stationary jaw structure 100. The auxiliary blade member 210 is retained in engagement with its cooperating contacts (not shown) until the main blade and its cooperating contacts have separated in a predetermined distance. At this time the auxiliary blade 210 then rapidly snaps out of engagement with its cooperating contacts, rapid action, together with the arc extinguishing characteristics of the chute 214 acting to minimize any arcing which may occur therein. The closing operation is performed in such a manner that the main blade makes engagement with its stationary jaw or with the contacts of the stationary jaw structure before the auxiliary blade 210, makes contact with its cooperating contact structure (not shown).

FIGURE 3 shows a prior art arrangement wherein the jaw structure 300 is comprised of a terminal portion 301 and a contact structure portion 302, similar in function to the terminal and contact structures of the jaw structure 100, shown in FIGURES la-lc. Contact structure 302 is provided with stationary arcing and stationary

main contacts

303 and 304 respectively, each of which comprise first and second contact surfaces positioned on opposite sides of the contact structure 302 in much the same manner as the

contact surfaces

106 and 107 of the jaw structure shown in FIGURE 111. FIGURE 3 shows the main blade 308 during a closing operation wherein the blade 308 is moving in the direction shown by arrow 309. At this instant of time there is only a minimum amount of separation between the right-hand end of the main blade 308 and the arcing stationary contact 303. At this time a voltage breakdown occurs setting up an arc current 310 between the main blade 308 and the arcing contact structure 303, thus establishing a current path 311. As can clearly be seen, the current path 311 has a severely looped portion 312. This looped portion sets up a magnetic field which tends to urge the main blade 308 away from the arcing contact 303 so as to severely impede the closing operation. This is highly undesirable since the persistence of the arcing condition, due to the main blade 308 being prevented from closing in on the arcing contact structure 303 :and subsequently the main contact structure 304, acts to cause a severe amount of deterioration of the arcing contact surfaces, as well as the main blade structure 308.

Turning now to FIGURE 1b, the main blade structure 208, shown therein during a closing operation, is moving in the direction shown by arrow 250. At this instant of time only a minimum amount of separation exists between the contact structure 105 and the main blade 208, setting up an electric current are 251 therebetween. As soon as the are 251 is formed, this establishes a current path 252. The loop portion 253 of the current path 252 can be seen to have an extremely greater radius of curvature than the looped portion 312 of the current path 311, shown in FIGURE 3 and for this reason any magnetic field which the current path 252 sets up will be significantly smaller than the magnetic forces generated by the current 311 of FIGURE 3. Thus the blow open effect created during the closing operation is substantially minimized so as to offer almost no restraint whatsoever upon the closing operation. In addition thereto, the placement of a high degree of mass concentration in the form of rib 113 immediately behind the

contact structure

106 and 107 permits the current path to extend directly to the terminal portion 101 so as to further aid in forming a less severe current loop between the jaw structure and the main blade 208. This arrangement thus permits the load interrupter switch 200 of FIGURES 2a and 2b to be utilized in power distribution systems having fault-current capacities far exceeding those in which present day interrupter switches may be employed. It has been found that a load interrupter switch using the contact structure of the instant invention may be closed in upon lines having current capacities of greater than 60,000 asymmetrical amperes, Whereas present day structures are capable of closing in on lines having current capacities less than one third as great. In addition thereto, by elimination of the stationary arcing contacts, the jaw structure has been greatly simplified, thereby substantially reducing the expense of both labor and materials in the production of such contact structures.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.

What is claimed is:

1. A stationary contact structure for use in load interrupter switch employing a rotatable blade movable into and out of engagement with said stationary contact; said stationary contact being a unitary member having a terminal portion, a base portion, a contact portion and a rib; said terminal portion and said base portion each having a first and second end; said first end of said terminal portion adapted to electrically connect an interrupter switch into an electrical circuit; said second end of said terminal portion being connected to said first end of said base portion; said contact portion having a bottom connected to said second end of said base portion and extending transverse from said base portion; said contact portion having a top which is initially engaged by a rotatable blade when the rotatable blade is being moved toward a closed position; said rib being a mass concentration of conductive material connecting the top of said contact portion to said second end of said terminal portion to provide a current path directly between the top of said contact portion and the second end of said terminal portion to bypass a major part of said base portion; the current path created by said rib substantially diminishing the blow-open effect occurring during 'a switch closing operation.

2. The stationary contact structure of claim 1 in which the top of said contact portion is tapered to form only one vertex for engagement with said rotatable blade; said tapered contact structure avoiding the need for providing both a stationary main and a stationary arcing contact thus substantially diminishing the blow-open elfect which occurs during a closing operation.

3. The stationary contact structure of claim 1 in which the top of said contact portion has a first and second contact surface on opposite sides thereof for engagement with said rotatable blade; said rib establishing a current path between said contact surfaces and said terminal portion to bypass said base portion and provide a loop current path which substantially diminishes the blow-open effect occurring during a switch closing operation.

4. A stationary contact structure for use in load interrupter switch employing a rotatable blade movable into and out of engagement with said stationary contact; said stationary contact being a unitary member having a terminal portion, a base portion, a contact portion and a rib; said terminal portion, said base portion, said contact portion and said rib all being integral; said terminal and base portion being substantially flat conductive members; said terminal portion and said base portion each having a first and second end; said first end of said terminal portion adapted to electrically connect an interrupter switch into an electrical circuit; said second end of said terminal portion being connected to said first end of said base portion; said contact portion having a bottom connected to said second end of said base portion and extending transverse from said base portion; said contact portion having a top which is initially engaged by a rotatable blade when the rotatable blade is being moved toward a closed position; said rib being a mass concentration of conductive material connecting the top of said contact portion to said second end of said terminal portion to provide a current path directly between the top of said contact portion and the second end of said terminal portion to bypass a major part of said base portion; the current path created by said rib substantially diminishing the blow-open effect occurring during a switch closing operation.

5. The stationary contact structure of claim 4 in which the top of said contact portion is tapered to form only one vertex for engagement with said rotatable blade; said tapered contact structure avoiding the need for providing both a stationary main and a stationary arcing contact thus substantially diminishing the blow-open effect which occurs during a closing operation.

6. The stationary contact structure of claim 4 in which the top of said contact portion has a first and second contact surface on opposite sides thereof for engagement with said rotatable blade; said rib establishing a current path between said contact surfaces and said terminal portion to bypass said base portion and provide a loop current path which substantially diminishes the blow-open effect occurring during a switch closing operation.

References Cited by the Examiner UNITED STATES PATENTS 9/1958 Foti 200-166 12/1959 Chabot 200-166

Claims

1. A STATIONARY CONTACT STRUCTURE FOR USE IN LOAD INTERRUPTER SWITCH EMPLOYING A ROTATABLE BLADE MOVABLE INTO AND OUT OF ENGAGEMENT WITH SAID STATIONARY CONTACT; SAID STATIONARY CONTACT BEING A UNITARY MEMBER HAVING A TERMINAL PORTION, A BASE PORTION, A CONTACT PORTION AND A RIB; SAID TERMINAL PORTION AND SAID BASE PORTION EACH HAVING A FIRST AND SECOND END; SAID FIRST END OF SAID TERMINAL PORTION ADAPTED TO ELECTRICALLY CONNECT AN INTERRUPTER SWITCH INTO AN ELECTRICAL CIRCUIT; SAID SECOND END OF SAID TERMINAL PORTION BEING CONNECTED TO SAID FIRST END OF SAID BASE PORTION; SAID CONTACT PORTION HAVING A BOTTOM CONNECTED TO SAID SECOND END OF SAID BASE PORTION AND EXTENDING TRANSVERSE FROM SAID BASE PORTION; SAID CONTACT PORTION HAVING A TOP WHICH IS INITIALLY ENGAGED BY A ROTATABLE BLADE WHEN THE ROTATABLE BLADE IS BEING MOVED TOWARD A CLOSED POSITION; SAID RIB BEING A MASS CONCENTRATION OF CONDUCTIVE MATERIAL CONNECTING THE TOP OF SAID CONTACT PORTION OF SAID SECOND END OF SAID TERMINAL PORTION TO PROVIDE A CURRENT PATH DIRECTLY BETWEEN THE TOP OF SAID CONTACT PORTION AND THE SECOND END OF SAID TERMINAL PORTION TO BYPASS A MAJOR PART OF SAID BASE PORTION; THE CURRENT PATH CREATED BY SAID RIB SUBSTANTIALLY DIMINISHING THE BLOW-OPEN EFFECT OCCURRING DURING A SWITCH CLOSING OPERATION.