US3784775A

US3784775A - Arc runner between stationary contacts

Info

Publication number: US3784775A
Application number: US00275523A
Authority: US
Inventors: C Gryctko
Original assignee: ITE Imperial Corp
Current assignee: Siemens Energy and Automation Inc; ITE Imperial Corp
Priority date: 1972-07-27
Filing date: 1972-07-27
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08

Abstract

A high current capacity molded case circuit breaker having arcing and main contacts and an arc chute to receive and extinguish arcs drawn between the arcing contacts is provided with a magnetic arc runner disposed between the stationary sections of the main and arcing contacts to direct arcs that initiate at the stationary main contact onto the stationary arcing contact.

Description

[ Jan. 8, 1974 1 ARC RUNNER BETWEEN STATIONARY CONTACTS [75] Inventor: Carl E. Gryctko, Haddon Heights,

[73] Assignee: I-T-E Imperial Corporation,

Philadelphia, Pa.

[22] Filed: July 27, 1972 [21] Appl. No.: 275,523

3,582,966 6/1971 Strobe] ZOO/144 R Primary ExaminerRobert S. Macon Att0meySidney G. Faber et al.

[57] ABSTRACT A high current capacity molded case circuit breaker having arcing and main contacts and an arc chute to [52] US. Cl. 200/146 R, ZOO/147 R receive and extinguish arcs drawn between the arcing [51] Int. Cl. HOlh 33/12 contacts is provided with a magnetic arc runner disl Field ar h /14 147 posed between the stationary sections of the main and ZOO/147 B arcing contacts to direct arcs that initiate at the stationary main Contact onto the stationary arcing [56] References Cited contact.

UNITED STATES PATENTS 3,171,936 3/1965 Jencks et a1. 200/147 R 9 Claims, 3 Drawing Figures 1 1 1" F] o 0 1 I o] 27/ 0 24/ m3: 7

i r" //'u I 'I i i 23 L. 1 l 11 .1 r a 1 .J 1 T 7 1 m w W 0 .1 G 0 L 7 w r 1 K? L 1 1 4 1 e1 1 1 1 I 13/ SHEEI 1 OF 2 g WWW ARC RUNNER BETWEEN STATIONARY CONTACTS This invention relates to molded case circuit breakers in general and more particularly relates to means for transferring arcs from the stationary main contacts to the stationary arcing contact.

Circuit breakers of high current ratings are provided with separate arcing and main contacts. In moderately high current rated breakers, arcing is confined to the arcing contact and aspaced plate type of chute is provided to receive and extinguish arcs formed on the arcing contact. However, for circuit breakers of very high current ratings, say 2,000 amperes and more, some initial arcing often takes place at one or more of the main stationary contacts. This condition has proven to be very serious in that there is normally no arc extinguishing means in the vicinity of the main contacts, so that arcs formed thereon hang on for an excessive period of time causing severe pitting of the main contacts.

In accordance with the prior art, are runners have usually been associated with the arcing contacts, usually positioned more deeply in the arc chute than the arcing contacts. For those structures in which arcing occurred at the main contacts, methods other than are runners were employed to prevent arcs at the main contacts from being made interrupting points of the circuit. To accomplish this, the prior art has utilized insulating shields positioned between the main contacts and the plates of the arc chute. With such a construction, if arcing occurred at the main contacts, this arcing was blocked from proceeding into the arc chute, but was expected to extinguish if and when arcingwas transferred to the arcing contact and its associated runner.

For very high current rated breakers, it has been found that arcing on the main contact does not always transfer to the stationary arcing contact, and if the main contacts are insulated from the arc chute, excessive damage will occur as a result of the are hanging on to the main contacts. The instant invention solves this problem by providing a magnetic arc runner between the main contacts and the arcing contact, so that arcs established at the main contacts are attracted to the magnetic arc runner which directs these arcs to the arcing contact where the. arcs enter the arc chute associated with the arcing contact and are extinguished.

Accordingly, a primary object of the instant invention is to provide novel means for minimizing arcing time at the main contacts of a circuit breaker.

Another object is to provide means of this type for directing arcs from the main to the arcing contacts.

Still another object is to provide a magnetic are runner positioned between the stationary main and arcing contacts to facilitate transfer of arcs, established on the ,main contacts, to the arcing contact.

These objects as well as other objects of this invention will become readily apparent after reading the following description of the accompanying drawings in which:

FIG. 1 is a longitudinal cross-section of a multipole circuit breaker, showing the elements of one pole thereof, including the arc runner of the instant invention.

FIG. 2 is an enlarged side elevation of the line terminal strap of FIG. 1, together with the stationary contacts and arc runner mounted thereon.

FIG. 3 is a plan view of the terminal strap of FIG. 2, looking in the direction of arrows 3-3 of FIG. 2.

Now referring to the figures. Multipole circuit breaker 25 includes a molded housing constructed of base 26 and removable cover 27 abutting at interface 28. The main current path through each pole of circuit breaker 25 is identical and consists of load terminal strap 61 connected by a plurality of

flexible conductors

120, 121*to the groups of movable main contacts 103, 107 engaged with stationary

main contacts

231, 232, respectively, extending across line terminal strap 136 and brazed or otherwise secured to the upper surface thereof.

Movable arcing contact 101, mounted at the forward end of arm 112, is engageable with stationary arcing contact 233, mounted on the upper surface of terminal strap 136 and positioned forward of stationary

main contact strips

231, 232. All of the

movable contacts

101, 103, 107 are mounted to contact carrier 45 that is pivotally mounted to mechanism frame 36, secured to base 26 by bolts 48. Contact carrier 45 is connected at pivot 46 at one end of lower toggle link 43 whose other end is connected to toggle knee 41. Upper toggle link 42 extends between knee 41 and pivot 44 on cradle 40, with the latter being pivotally mounted at 47 to frame 36.

Transverse cradle portion 40a mounts latch plate 51, engageable by secondary latch 53, which is connected to primary latch 65, pivoted on trip unit frame at stub shaft 69. Primary latch is in turn engageable by the latchplate portion of carrier 66, to maintain cradle 40 in the latched position shown in FIG. 1, wherein circuit breaker 25 may be operated from its open position of FIG. 1 to its closed position. When carrier 66 releases latch train 53, 65,the movement of cradle 40 is transmitted back through latch train 53, 65, whereby transverse pin 71 is moved by primary latch 65 to pivot carrier 66 about shaft 68, thereby moving transverse common trip bar to release the latch systems of all other poles.

lnstantaneous trip means in the form of stationary magnetic frame members 96, 98 and movable armature 78 is provided. Also provided is a delay trip means in the form of bimetal strip 77 mounted to insulating member on trip unit frame60.

Transverse insulation bar 147 extends through tubular members 146 at the rear of each contact carrier 45 to mechanically connect the contact carrier 45 of all poles. Aligned apertures 148 in the sides of frame 36 provide clearance for movement of bar 147. Toggle 42, 43 is operated by spring means (not shown) connected between plate 39, on toggle knee 41, and the upper end of operating member 35 pivoted at its lower end to frame 36. Member 36 is connected by studs 34 to circuit breaker operating handle 30, which is provided with stubby bifurcated extension 33 extending through aperture 29 in housing cover 27. Handle extension 33 mounts roller 222 that isengaged by the operating elements 235 of auxiliary handle operating mechanism 250, having main operating handle 253 for moving elements 235.

During normal operation, as

movable contacts

101, 103, 107 separate from

stationary contacts

233, 231, 232 respectively, arcing will be confined to arcing

contacts

101, 233. The are formed between

arcing contacts

101, 233 is drawn deeply into spaced plate type arc chute 240, having upper and lower

magnetic arc runners

241, 242, with the latter being secured to the upper surface of terminal strap 136 by screws 243.

In accordance with the insant invention, magnetic steel arc runner 255, secured to the upper surface of terminal strap 136 by screws 271, is disposed immediately in front of the forward stationary main contact 231 and extends into the mouth region 256 at the rear of arc chute 240, where stationary arcing contact 233 is disposed. The front edge of arc runner 255 tapers downward from rear to front and terminates along the sides of stationary arcing contact 233.

The presence of magnetic arc runner 255 causes arcs established at stationary

main contacts

231, 232 to move forward and transfer to stationary arcing contact 233 with sufficient rapidity to prevent excessive pitting of

main contacts

231, 232. Once the arc transfers to stationary arcing contact 233, arc chute 240 causes the arc to be elongated and extenguished rapidly.

For those features of construction in circuit breaker 25 that have not been described in detail herein, reference is made to one or more of the copending applications Ser. Nos. 275,568, 275,577, 275,446, 275,578, 275,507, 275,454, 275,508, 275,621, 275,623, 275,624, 275,569, 275,522, 275,521, and 275,622, all filed of even date herewith, and all assigned to the assignee of the instant invention.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now become 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.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows.

l. A circuit breaker comprising stationary contact means including stationary arcing and main contact sections; movable contact means including movable arcing and main contact sections operable into and out of engagement with said stationary arcing and main contact sections, respectively; arc chute means to receive and extinguish electric current arcs drawn between said movable and stationary contact means upon separation thereof; said stationary main contact means being disposed outsideof said arc chute; said are chute having an entrance region; said stationary arcing contact means being positioned at said entrance region; and magnetic arc runner means positioned at said entrance region and interposed between said stationary arcing and main contact sections to transfer arcs from said stationary main contact section to said stationary arcing contact section and into said are chute means where these arcs are extinguished.

2. A circuit breaker as set forth in claim 1 also comprising an elongated terminal strap supporting on its upper surface said stationary arcing and stationary main contact sections, with the latter being behind the arc chute means and the stationary arcing contact section; said are chute means extending above said terminal strap.

3. A circuit breaker as set forth in claim 2 in which the arc runner means is tapered downward from rear to front.

4. A circuit breaker as set forth in claim 3 in which the arc runner means at the rear end thereof extends across substantially the entire width of the terminal strap.

5. A circuit breaker as set forth in claim 4 in which the stationary main contact section extends across substantially the entire width of the terminal strap.

6. A circuit breaker as set forth in claim 5 in which the stationary main contact section includes first and second elongated portions extending substantially across the terminal strap.

7. A circuit breaker as set forth in claim 5 in which the stationary arcing contact section is substantially narrower than said stationary main contact section, and the arcing runner is constructed of steel.

8. A circuit breaker as set forth in claim 2 also including additional magnetic arc runner means extending forward of said arcing contact means and operatively positioned to draw arcs formed beteween separable sections of said arcing contact means deeply into said arc chute.

9. A circuit breaker as set forth in claim 2 in which said magnetic arc runner means covers a substantial portion of sait terminal strap upper surface in the region thereof between said stationary arcing and stationary main contact sections.

Claims

1. A circuit breaker comprising stationary contact means including stationary arcing and main contact sections; movable contact means including movable arcing and main contact sections operable into and out of engagement with said stationary arcing and main contact sections, respectively; arc chute means to receive and extinguish electric current arcs drawn between said movable and stationary contact means upon separation thereof; said stationary main contact means being disposed outside of said arc chute; said arc chute having an entrance region; said stationary arcing contact means being positioned at said entrance region; and magnetic arc runner means positioned at said entrance region and interposed between said stationary arcing and main contact sections to transfer arcs from said stationary main contact section to said stationary arcing contact section and into said arc chute means where these arcs are extinguished.

2. A circuit breaker as set forth in claim 1 also comprising an elongated terminal strap supporting on its upper surface said stationary arcing and stationary main contact sections, with the latter being behind the arc chute means and the stationary arcing contact section; said arc chute means extending above said terminal strap.