US3505488A - Stationary contact structure forcing blow out shaped current path - Google Patents

Description

April 7, 1970 V. A14,13,MccgnqNELL 3,505,488v

STATIONARY QORTACTy STRUCTURE FoRcING v BLowvoUTlsHAPED CURRENT PATH Filed Jan. 2v, l19s? 4 sheets-sheetA 1 April 7, 1970 l.. n. MCCONNELL f 3,5055488 STATIONARY CONTACT STRUCTURE lFORCING v Filed Jan. 27, 196'? BLOW OUT SHAPED CURRENT PATH 4 Sheets-Sheet 2 Fr inrdr April 7, 1970 L MCCON- ,LL y, 3,505,488

savmomxmfy TAcT STR FoRoING BLow ouTv SHAPED CURRE PATH Filed Jan. 27, 196'? 4 Sheets-Sheet 3 April 7, 1970 L D, MCCONNELL 3,505,488

STATIONARY CONTACT STRUCTURE FORCING BLOW OUT SHAPED CURRENT PATH A Filed Jan. 27. 1967 4 Sheets-Sheet 4 Er-E5- United States Patent O STATIONARY CONTACT STRUCTURE FORCING BLOW OUT SHAPED CURRENT PATH Lorne D. McConnell, Sierra Madre, Calif., assignor, by mesne assignments, to I-T-E Imperial Corporation,

Philadelphia, Pa., a corporation of Delaware Filed Jan. 27, 1967, Ser. No. 612,216 Int. Cl. H01h 33/ 86 U.S. Cl. 200-148 2 Claims ABSTRACT OF THE DISCLOSURE A nozzle-shaped stationary contact having an insulation spacer ring extending to the interior opening thereof to force current flow through the stationary contact to have a generally sharp bend therein so that the current path from the stationary contact to the movable contact will cause' a blow out force on the arc. Radial slots are formed in the stationary contact to prevent circumferential current flow therein.

This invention relates to a novel contact structure for gas blast interrupters which provides a novel shaped current path which causes a magnetic blow out force on an ar-c extending between the stationary and movable contacts and is an improvement for the stationary contact structure shown in eopending application Ser. No. 601,985, led Dec. 15, 1966, entitled Annular Sliding Valve for Air Blast Circuit Breaker, in the name of John Golota, and assigned to the assignee of the present application.

In the foregoing application, a novel gas blast circuit interrupter is formed wherein the blast valve is directly adjacent the region of separation of the stationary and movablecontacts with the blast valve sealing on an annular gasket Icarried in the stationary contact. Thus, high pressure arc extinguishing gas is available the instant the valve is opened without any pressure loss or delay due to the usual arrangement where a blast valve is positioned remotely from the arcing area.

The arcing region between the movable and stationary contacts of the above noted application can exhaust in two directions: The major direction for arc product exhaust is through a central opening in the annular stationary Contact and outwardly through cooler plates through the external atmosphere, while a second exhaust path is provided downwardly through a lcentral opening in the movable contact. Moreover, when the movable Contact is opened, a third channel is exposed which leads to the high pressure annular chamber surrounding the subassembly of movable valve and movable contact with the high pressure blast gas coming from this annular chamber.

It has been found that when the current path extending from the stationary contact to the movable contact is generally perpendicular to entrance of this annular chamber, magnetic force acting on the arc drawn between the sepa- A' rating contacts can tend to drive the arc downwardly into .this annular pressure supply chamber rather than outwardly of the chamber where the arc can be better stretched and cooled for extinction.

The principle of the present invention is to provide a novel insulation spacer within the body of the stationary Accordingly, a primary object of this invention is to lee provide a stationary contact arrangement for gas blast interrupters which cause a blow out force on the arc tending to drive the arc outwardly of the main pressure source for forcing an air blast through the arc.

Yet another object of this invention is to provide a novel current path shape for gas blast circuit interrupters having a blast valve immediately surrounding the interrupting area between the cooperating contacts which causes a blow out force on the arc to move the arc into the most suitable arc interrupter region provided in an interrupter.

'Ihese and other objects of this invention will become apparent from the following description when taken in connection with the drawings, in which:

FIGURE 1 is a ycross-sectional view of the novel interrupter structure of the invention in the open position.

FIGURE 2 is similar to FIGURE 1 and shows the interrupter structure in its closed position.

FIGURE 3 is a bottom plan View of the stationary contact of FIGURE l.

FIGURE 4 is a cross-sectional view of the upper terminal structure for the interrupter for FIGURES 1 and 2.

FIGURE 5 is a cross-sectional view of FIGURE 1 taken across lines 5-5 in FIGURE 1.

FIGURE 6 illustrates a modication of the stationary contact structure shown in FIGURES 1 and 2 which Acreates a current path from the stationary contact to the main contact which tends to induce a blow out force on the arc to keep the arc from travelling downwardly into the main pressure storage chamber.

Referring now to the drawings, the interrupter chamber is comprised of an insulation tube 10 of suitable material which is tted and sealed in conductive mounting disks 11 and 12 at its upper and lower ends, respectively. Upper disk 11 is then secured to the disk-shaped stationary contact 12a, shown in bottom plan view in FIGURE 3. A gas conducting discharge outlet including tube 13 shown in FIGURE 4 is connected atop contact 12a and contains a standard stationary arcing contact finger 14 surrounded by a cooler honeycomb 15, schematically illustrated, which conducts blast gas through openings in terminal plate 16 to the exterior of the interrupter. The bottom disk 12 is then secured to bottom casting 20'.

Bottom casting 20 is secured and sealed on the end of 'a suitable hollow support insulator 21 with a source of high pressure gas,l such as air (not shown) connected to the bottom of insulator 21 and thus to central chamber 22 beneath casting 20. Casting 20 has' a channel 23 for conducting this high pressure gas through valve seat 24 formed in casting 20. A-valve member 2,5 carried on rod 26 is then movable between valve seat 24 and valve seat 27 which is suitably fastened to bottom casting 20, with valvemember 25 normally biased toward engagement with valve seat 27 by the compression spring 28. A suitvable operating mechanism (not shown) is connected to rod 26 from some remote position and is responsible for movement of valve 25, as will be later described. p

Channel 23 then communicates with channel 28a in bottom casting 20. The upper portion of channel 28a leads into an annular channel 28a surrounding lower conductive member 29 which .is secured 4to casting 20.

`Conductive member 29 has a flange 30 thereon and ber 29 as illustrated. The movable contact rod 32 has an opening 35 extending therethrough, and is provided with a series of resilient butter plates such as plates 36, 37 and 38, the bottom plate of which is received by the top of member 29 when the movable contact 32 is in the open position shown in FIGURE 1.

A biasing spring 39 contained between flange 30 0f xed member 29 and ange 40 of the movable contact rod 32 then biases the contact rod 32 upwardly toward the position of FIGURE 2.

Contact rod 32 is in sliding contact engagement with upper conductive cylinder portion 50 of bottom casting 20 by means of a plurality of sliding contacts 51 which surround the contact rod 32. By way of example, six such sliding contacts 51 can surround rod 32 as illustrated in FIGURE 5. Each of contacts 51 are then biased outwardly and into sliding engagement with member r50 as by suitable compression springs 52.

The exterior surface of contact rod 32 is then provided with a shoulder 60 which serves as a stop for annular blast valve member 61 which telescopes over the upper end of contact rod 32. A spring 61a is provided between shoulder 61b on movable contact rod 32 and the interior of valve 61 which biases valve 61 upwardly with respect to contact rod 32. lBlast valve member 61 has a lower cylindrical skirt 62 which ts over member 50 with a gastight seal formed between members 61 and 50 by the O-ring 67. A second seal is formed between member 61 and contact rod 32 by the O-ring 68.

Annular valve 61 is then movable from the lower open position of FIGURE l to the -valve closed position of FIGURE 2 where the outer surface annular valve `61 seats against O-ring 69 carried in the stationary contact 12a.

It is to be noted that movable contact rod 32 is movable independently of valve 61 to the disengaged position (from the position of FIGURE 2 to the position of FIGURE 1), and that when the contact 32 engages stationary contact 12a, it engages on a radially inwardly directed portion 70 of the inverted S-shaped engaging surface of stationary contact 12a.

An annular cavity 80 is then provided within skirt 62 which is connected to channel 28a to permit compressed gas from cavity 22 to ll cavity 80'. Channel 22 is connected to main annular chamber 81 formed between the interior of tube and lthe exterior of extension 50 by virtue of the spider type construction of casting 20 as illustrated by dotted lines in FIGURES 1 and 2. Note that channel 28a and chamber 81 are in communication with one another only when valve 25 is in the position of FIGURE 1, through the common channels 23 and 28. When valve 25 moves down (and seats on valve seat 24) channel 28a and chamber 81 are isolated by valve 25.

The operation of the interrupter of FIGURES 1 and 2 is as follows:

With the circuit interrupter in the closed position of FIGURE 2, compressed air is admitted through chamber 22 through conduits 23 and 28, the valve 25 being in its upper position where it seats against valve seat 27. The pressure from chamber 28 is then applied under ange '40 of movable contact 52 to aid spring 39 in closing contact rod 32, and to the interior volume 80 under valve 61 to aid spring '61a to close the valve 61, thereby to bias both valve 61 and contact 32 to the engaged position in FIGURE 2. The valve 61 seats on ring 69, thereby to prevent compressed air in chamber 81 from escaping through the center of contact 12a or through channel 35 in contact rod 32.

In order to open the circuit interrupter, the valve 25 is remotely actuated through a suitable operating mechanism which is unimportant for purposes of the present invention, whereby the valve 25 is moved down to seat against valve seat 24. This then vents chamber 28a to the external atmosphere, thereby permitting the pressure beneath the annular valve 61 to fall off rapidly. The valve 61 is so proportioned that the area under the valve within chamber is less than the area at the top of the valve exposed to the pressure within the outer chamber 81, thereby tending to move the valve toward its lower or open position against the force of spring 61a. Moreover, when the pressure has fallen suiciently to allow the valve to move downwardly and break the seal at gasket 69, the area on top of the valve subject to the higher chamber pressure will now be equivalent to the full area of the valve including the area which was internal of seal 69 which was exposed only to external pressure. That is, as shown in FIGURE '6, the full valve area including areas 61e and 61d, which are internal and external of valve 69, will be exposed to high pressure after the valve opens. This sudden increase in area and resultant multiplication of opening force will then drive valve 61 rapidly down against shoulder 60 of movable contact 32 and independently of movement of movable contact 62.

When the valve 25 vents chamber 28a, pressure under flange 40 of movable contact rod 32 was also removed. However, the force of spring .39 is still sufficient to hold contact rod 32 in engagement with stationary contact 12a. As soon as valve 61 leaves seal 69, however, the entire upper surface of contact 32 is exposed to the high pressure of chamber 81 which is suflicient to move contact rod 32 rapidly downward against the force of spring 39.

Consequently, in operation, valve 61 is initially unsealed from seal 69 whereupon it immediately moves downward, independently of contact 32, with a popping type action once the remainder of its internal area within seal 69 is exposed. Similarly, the movable contact is exposed to high operating pressure immediately after valve 69 is opened, whereupon contact 32 also moves down with a popping action. Since valve 69 opens immediately prior to separation of contacts 32 and 12a, a strong air blast will be established between the separating contacts to extinguish any arc drawn therebetween. This air blast is then conducted through the cooler honeycomb 15 (FIGURE 4) to external atmosphere, and through central-opening 35 and through honeycomb 31 to external atmosphere. Note further that there is no delay in application of blast air to the contact after thel blast valve is opened since this air (and the blast valve) surrounds the contact area and need not be conducted through auxiliary channels. Thus, air blast need continue only long enough to extinguish the arc whereby compressed air of the supply is conserved. Moreover, the air pressure at the contacts has the same pressure as the supply source (as measured in cavity 22), and it is not necessary to increase the air supply pressure to account for pressure drops in conduits leading from the blast valve to the contact.

In order to shut olf the blast of air and reset the contacts, the operating mechanism moving valve 25 is suitably arranged so that the valve 25 is automatically returned to the position shown in the drawings where the valve 25 seats against valve seat 27. This action will permit compressed air to enter channel 28a and chamber 80, thereby moving the valve 61 upwardly to seal against O-ring 69 with a snap action. The closing of valve 61 removes the pressure from the top of contact 32 whereby the pressure beneath flange 40 and spring 39 will move contact 32 toward its engaged position with a subsequent snap action.

Note that a supplemental isolating Contact means (not shown) will be connected in series with the interrupter contacts in the usual manner. This interrupter is synchronized with the operation of valve 25 to establish an open circuit to prevent the reclosng of contact 32 from re-establishing the circuit which has been opened.

It is to be particularly noted that the air pressure within the movable contact chamber acts independently on both contact 32 and annular valve 61. In this manner, the contact force is made independent of the sealing force and 2"adds-@tothe force -obtainedafrom :the-.main closing spring 39. This results in high contact pressurebetween contacts 32 and 12a up' tothe instant of contact separation. At the s arne time, the force underannular valve 61 is proportionally lower so as to not develop excessive sealingpressure, thereby allowing the `valve-to be yof-light construction so that it'willberapidly movable-under the differential pressures applied thereto "during opening.

Referring now to FIGURE6,"t-her`e` isillustrated therein a modification of the stationary contact structure shown in FIGURES l and 2 which incorporates the present invention and illustrates other'con'struction variations.

FIGURE 6 illustrates thegupper conductive mounting disk 11 which receives the main insulation tube 10 and is secured to its top. A modified stationary contact 100 is provided with au outer shoulder 101 which can, for example, receive a suitable discharge outlet including the tube13 of FIGURES 1 and 2. y

FIGURE 6 additionally shows the upper portion of sleeve 50 which contains movable contact 32. Note that in FIGURE 6 the movable contact 32 is composed of three sections: A lower body section 32a which threadably receives the upper contact section 32b which is terminated with an arcing tip 32C which could be composed of some suitable arc resistant material. In addition, the movable valve 61 is shown with a foreshortened nose section 61b which terminates on gasket 67 in the manner disclosed in copending application Ser. No. 611,600, filed Jan. 25, 1967, entitled Shaped Nose Section on Movable Ring Valve, inthe name of Daniel H. McKeough. Note further that a conductive liner 112, which may be of aluminum, is suitably bolted around the upper interior of tube to prevent burning of the interior ofglass tube 10 if ionized air 'should be blown back into chamber 81.

The stationary contact 100 is then composed of a plurality of sections including lower ring 110 which' is sealed to xternal tube' 10 by a suitable gasket 111. The annular 'gasket 69 which cooperates with valve 61 is then clamped into position within shoulder 113 of ring 110 by an insulation clamp 114. The insulation material such as Teflon and its outer surface is presented to and is continuous with the outer surface of arcing contact section 32e of the movable contact 32. An arcing contact ring 120 is then placed on top of insulation ring 114 and is composed of a conductive body 121 having an internal lining of suitable arc resistance material which forms the contact portionl of the stationary contact which cooperates with arcing tip- 32a` f movable contact 32.

'The entire stationary contact assembly is then held in position by means of the upper conductive clamping plate 123 which is held in position by suitable bolts such as bolt 124` which extends through clamping plate 123 and plate 120 and is threaded into tapped openings in ring 110. The above arrangement is the subject of copending application Seri No. 605,795, filed Dec. 29, 1966, in the name of I ames R. McCloud, entitled Stationary Contact Having Sealing Gasket Support Structure, and assigned to the assignee of the present invention.

'In accordance with the present invention, an insulation spacer 125 is disposed between interior portions of clamp 123 and contact section 120 in order to define the current path 126 shown in dotted lines from stationary contact 10'0 to the movable contact 32 to create a blow out force tending to drive the arc drawn between arcing contact sections 32e and |122 outwardly rather than toward the interior of chamber 81.

That is to say, where a relatively direct current path can fbe established, as illustrated by the contacting arrangement in FIGURES 1 and 2, from contact 70 to contact 32, it is possible to set up magnetic forces on the arc tending to drive the arc and its arc products downwardly and over gasket 69 in FIGURES 1 and 2 and into chamber 81. In this event, severe damage could occur to the critical surfaces 69 and blast valve 61 and ionized gas can enter and coat the interior surface of insulation tube 10.

l122 into at least two, and preferably four quadrants by four-radial4 spaces between the quadrants. These spaces or slots will prevent a closed-loop or lateral currentl flow around the contact: which, if permitted, would tend to cancel out the intended blow-out loop action. One such slot is shown in FIGURE 6 as slot t130.

Although this'inventionhas beendescribed with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, but only by the appended claims.

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

1. A vgas blast circuit breaker comprising, in combination: a stationary contact; an elongated movable contact movablev between an engaged and disengaged position with respect to said stationary contact; an annular blast valve of insulation material surrounding said elongated movable contact; said annular blast valve having an interior surface portion extending along a major portion of the axis thereof; said interior surface portion engaging and being axially slidably movable on the exterior surface of said movable Contact; said annular blast valve having first and second opposite annular surfaces facing respectively toward and away from said stationary contact; a first chamber in communication with said second annular surface of said blast valve; a high pressure gas source; valve means for selectively connecting said first chamber to said high pressure source or to a low pressure exhaust region respectively; a second chamber connected to said high pressure gas source; said movable contact and said annular blast valve contained within said second chamber; an opening in said second chamber adjacent the end of said elongated movable contact and in the region where said movable contact engages said stationary contact; seal ring means disposed in said opening and engageable by an exterior annular region on said first annular surface of said annular blast valve; said first annular region dividing said first annular surface into an interior annular portion and an exterior annular portion; said opening in said second chamber communicating with a low pressure region; said end of said movable contact exposed to said low pressure region when said first annular surface of said annular blast valve engages said seal ring means and said movable contact engages said stationary contact; connection of said first chamber to said low pressure region by said valve means permitting the release of said first annular surface of said annular blast valve from said seal ring means whereby high pressure from said second chamber is connected over the full surface area of said first annular surface of said blast valve to move said blast valve down along said movable contact and said high pressure source is connected over the end surface of said movable contact, thereby to move said movable contact down and away from said stationary contact with the opening of said blast valve permitting a blast of high pressure gas through the region between the separating movable and stationary contacts; said stationary contact comprising a ring shaped conductive body having a central opening therein defining said opening in said second chamber; said movable contact engaging the interior walls of said central opening at a generally axially central plane around said interior surface; the improvement which comprises an insulation ring in said stationary contact body to force a current path 7 through said stationary contactto saidmovable contact which has a relatively sharp downward bend where current enters said movable contact; said insulation ring embedded in said stationary contact and disposed in a plane parallel to said central plane and'having an outer diameter greater than the inner diameter of said central 4 opening at said central plane; said ring shaped contact having at least one angularly disposed radially extending gap therein to prevent a circular current flow circurnferentially around said ring shaped stationary contact.

2. The deviceas set forth in claim 1 wherein said stationary contact is comprised of an upper and lower section; said insulation ring interposed between said upper and lower sections; and common clamping means for t 8 clamping-'together said'luppertand low sections and said insulation ring.j f i ,i L. c v

A' References Cited t l UNITED STATES `PATENTS 3,226,513` 12./-1965 l Frowein et al. 200-148 .3,082,307 '3/l963' Greenwood et al. t

3,274,365 9/1966 Beatty, l

'35336,454 `8/1967 Beatty et al. 200-148 u FOREIGN PATENTSy v 31,069 9/ 1964 Germany. l l

ROBERT S. MACON, Primary Examiner

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