US3032632A - Circuit interrupters - Google Patents

Description

May 1, 1962 E. F. BEACH ETAL CIRCUIT INTERRUPTERS 5 Sheets-Sheet l Filed July l, 1959 INVENTORS Eorl E Beach 8 George N. Coker ATTORNEY May 1, 1962 E. F. BEACH ETAL CIRCUIT INTERRUPTERS 5 Sheets-Sheet 2 Filed Jul;)r 1, 1959 May 1, 1962 E. F. BEACH ETAL 'cIRcUIT INTRRUPTERS 5 Sheets-Sheet 3 Filed July 1, 1959 F ig .4.

Fully Open Position May 1, 1962 F. BEACH ETAL cIRcUIT INTRRuPTE-Rs 5 Sheets-Sheet 4 Filed July l. 1959 Fig.6

United States Patent Office 3,0372,'632 j CIRCUIT NTERRUPTERS Earl F. Beach, Pittsburgh, and George N. (Joker, Irwin, Pa., ssignors to Westiughouse Electric Corporation, East Pittsburgh, Pa., a corporation of Peiinsylvania FiledJuiy 1', 195,,Se 1f;- No, 824,286 4 Clairns. (Cl. 200-148) This invention relates to 'circuit interruptersin general, 'an'd more particularly, to 'circuit interrupters which u'tilize a fluid ;for arcLextinguishin'g purposes. The invention has particular applicability when applied -as the interrup'ting unit for a load-breakjdisconnectihg switch.

A general object of the present invention is to provide van improve'd 'circuit interrupter, which will 'more effectively bring about arc extinction than has been obtained h'eretofore.

Another object of the nvention is to provide an improved, circuit-interrpting `unit involving4 light parts 4adaptable for high-speed motion, ah'd in which a valve ar'- rangement is associated with 'the arcing Chamber to pro'- vide a fiow of fluid quickly into the arcing chamber following Vcircuit interrupti'on, to be in readiness for any subsequent opening operation which 'might occur'.

Another object of the invention is to provide an improved circuit-interrupting unit of the type establishing two breaks in series,'on`e break being employ'e'd as a pressure-generating break, whereas the other break is utilized as an interrupting break to 'obtain a c'o'ol fiw of fiui'd toward the iuterruptihg break. w

Yet a further object of the invention is to v'provide an improved interrupting unit, in which the pressure, initialtly established, is confine'd within a substahtially closed ar'cing charnber, which is subsequently opened by the withdrawing m'otion of the mov'able contact, and in which the confinedjgase's are then ejected from the arcing cham- Ibei' yto quickly bring about Aextinction of the a-c. Preferably an orifice structure is associated with the arcing chamb'er to more eifectively direct the airc gases.

Another objectjof the present invention is to employ a hormally-open-valve mechanism associated with an arcing chamber, which will be closed during the high-pressure interupting period, but which will subsetjuently open following arc exti'nctioii, to permi-t a convection flow of fluid 'back into the arcing charnber, so that the interrupting unit will be in readih'ess for any subsequent opening operation. Still a further 'object of the invention is to provide an 'improved circuit-interrupting unit, which is particularly 'adapte'd for use in a lod-break disconnectihg switch, so that the ejectioh of the niov'abl'e coh'tact rod` frbm the arcihg c'hainber will 'assis't 'the overc'ent'er spring associated 'ith theV overcenter-sp'ririg mechanisrn employed with the dead-break disco'nnectihg switch to provide very highspeed operation.

i In US, Patent 2,7"69,0`63, issued October 30, 1956, tO Harry J. Lih'gal, ahd assigned to the assignee of the instant application, there is disclosed and clairned a novel circuit-interruptihg unit vassociated with a load-break disconnecting switch. The Lingal interrupting unit is highly effective for certain appiications, but for the higher current ratings it has beeh found that the weight of the movirigl parts issuch that in some cases itytakes about lsir cycles to 'obtaiii a lcontact ;travel of eight inches. f This cause's the c'oht'act tips to burn away and 4to erode the orifice structure to the point Where lthe orifice structure is somewhat impaired as. an eificient-interrupter. The amount of spring force available for accelerating the `moving contact rod cannot be increased in the Lingal load-break disconuect'ing switch, since the eifort required to 'operate 'the switch 'is already 'at a maximum.

It is 1a Yfurtl'ier object of the present 'invention to pro- 3,032,632 Patented May 1, 1962 vide an improved structure to vreplace the interrupting unit as described in the laforesail Lingal patent, by speeding up the contact-rod travel, by changing'the moving contact to a simple rod, and by making the interrupter an ekplosi'oh pot Less burning time on the contact tips 'will consequently provide a longer Operating life. Moreover, the construction set 4forth in the instant application provides for -a lower-cost interrupter, as well as a more efiicient 'interrupter than that described in the aforesaid ingal patent.

Fuither objects andadvantages will readily become appai'eht, upon feading the following specification, taken in conjunction with the drawiugs, in which:

FIG. 1 is a side elevation'al view of a load-break dis- 'cohnecting switch incorporating the improved circuit in- "terruptig Vdevice of the present invention, the contact structure being shown in the closed-circuit position;

PIG. 2 is an enlarged, fragmentary Vertical sectional view taken through the interrupting unit of the load-break disconnecting switch of FiG. 1, the contact and mechani'sin parts being illus'trated in the closed-circuit position;

FIG. 3 is a 'fragmentary view, similar to that of PIG. 2, but showing the disposition of the mechanism parts at the point where the moving contact rod Will be tripped to the open position; x

FIG. 4 is a fragmentary view, similar to that of PIG.) 3, but illusftrat'ing the position of the several parts in the fully opflehcir'cuit position; I

FIG. 5 is a fragmentary view, similar to those of FIGS. 3 and 4 but indicating the point during the closing stroke, at which the niovihg contact rod is just ready to be snapp'ed to its closed-circuit position;

FIG. 6 is a Vertical sctiona'l view taken through the interruptng device of the present invention, the contact 'parts being illust'r'ated in the closed-circuit position;

FG. 7 'illust'r'ates a modified type of interrupting unit, which may be employed in place of the interrupting unit 'of FIG. 6, again the contact parts being illustrated iu the closed-circuit position;

BIG. 8 is a view similar to FIG. 6, but showing the dis- 'p'osition of the parts when the moving contact rod .has just 'cleared the orifice and arc exti'nctioh is occurring; and, v

FIG. 9 is a view similar to that of FIG. 7, but illustrating the disposition of the several contact parts at the instant of a'rc extin'ction.

Referrihg to the d'rawings, and more particularly to FiG. 1 the'reof, the reference numeral 1 generally ;designates a load-break.dsconh'ecting switch. As well known by those 'skilled in the 'ar-t, in many instances it is desir- 'able t'o open a high-voltage disconnecting switch while normal load current is fiowing in the circuit in which it lis connected. 'For example, in many installations, high voltage transformers are constantly connected to the highvoltage line and infrequently require servicin'g. It is then necessary to disconnect such 'a high-voltage transformer from the high-voltage circuit, and during such disconnecting operation, it is necessary to interrupt the magnetizing curreht flowing from 4the high-voltage line into the highvoltage transfo'rmer'..

If this magfieti'zing cu'n'rent were drawn' between lthe blade-shap'ed contact `and the stationary jaw contact of a iconve'nti'onal disco'nnecting switch, the contact surfaces would become pitted, vor eroded, so that following only a few such Operations, the contact lsurfaces would not be suitable for carryih'g the full-load current. Thus, the 'switch members would become burned, orfused because of the hefat 'of :the `ajrc ,depending upon the Vamount of current in the circuit at the particular instant that the switch is opened.

Consequently, in a load-break disconnecting switch an 3 auxiliary interrupting device is associated with the break end of the switch to interrupt the current in an arcextinguishing device, so that the current will not be broken at the open switch contacts.

As noted in FIG. 1, there 'are provided three insulator stacks 2, 3 and 4. These insulator stacks are supported upwardly from a channel-shaped base 5. However, it is to be clearly understood that the load-break disconnecting switch 1 may be mounted vertically or even inverted, as well known by those skilled in the art. Merely for purposes of illustration is the device illustrated in an upstanding position, as shown in FIG. 1. Supported upon the insulator stack 2 is a cam housing 7, interiorly of which is disposed a cam mechanism 6 for etfecting the operation of a main switch blade 10. It will be noted that the insulator stack 2 -is rotatable, being mounted upon a bearing 9, and the rotation thereof eifected by a crank arm 8. Consequently, to open the disconnecting switch 1 from the closed-circuit position thereof, as shown in FIG. 1, suitable means, not shown, effects counterclockwise rotation of the orank arm 8 and hence insulator column 2. This rotating movement of insul'ator column 2 actuates a cam interiorly within cam housing 7, in a manncr more fully disclosed in U.S. Patent 2,436,296, issued February 17, 1948, to Howard W. Graybill and Paul Olsson, and assigned to the assignee of the instant application.

The actuation of 'the cam mechanism 6, disposed within cam housing 7, will cause clockwise rotation of a main switch blade, generally designated by the reference numeral 10, from the position shown in full lines in FIG. 1, to the dotted-line position, indicated by the reference numeral 42.

This will cause the contacting end 11 of the main switch blade to part company with stationary main switch jaws 12, which are supported 'at the upper end of the insulator stack 4. To prevent the load current being interrupted at the open contacts 11, 12, a circuit-interrupting device, generally designated by the reference numeral 13, is associated with the stationary jaw contacts 12. To effect the actuation of the circuit interrupting device 13, the -tip end, or tn'pping stud portion 14 of the main switch blade Strikes a laterally jutting 'actuating rod 15, which is supported from a Crank arm, or tripping lever, generally designated by the reference numeral 16. The erank arm 16 is fixedly secured to the outer end of the drive or Operating shaft 1'7, which effects the actuation of 'an overcenter spring mechanism, which is disposed within a mechanism housing 21. As shown in PIG. 1, the mechanism housing 21 is disposed at the upper end of the circuit-interrupting device 13. The stationary insulator stack 4 also supports a terminal pad 22 which constitutes a portion of a base casting 23.

As shown more clearly in FIG. 2 of the drawings, a stationary contact rod support 24 extends upwardly from the base casting 23. At the upper end of the stationary contact rod support 24 is a stationary contact 25, as shown in FIG. 8. Cooperable with ythe stationary contact 25, interiorly of the circuit-interrupting device 13, is a movable contact 26, which is carried by a movable contact rod 27. The upper end of the movable contact rod 27 terminates in an upper rod-end 29, to which is fixedly secured a flexible connector 30, which, as shown in FIG. 2, has itsother end fixedly secured to the mechanism housing 21. The upper interrupter terminal for the circuitand 3 is a support casting 36, which has a line-terminal connection plate 37 integrally formed therewith.

From the foregoing description, it Will -be noted that in the closed-circuit position of the device, as illustrated in FIG. 1, the electrical circuit therethrough includes terminal pad 22, base casting 23, stationary main switch jaws 12, contact 11 of main switch blade 10, through cam housing 7 and support casting 36 to the right-hand terminal pad 37.

During .the opening operation, following separation between the contact 11 of switch blade 10 from stationary jaw contacts 12, the circuit is compelled to fiow upwardly through the circuit-interrupting device 13. This path includes terminal pad 22, base casting 23, base plate 89 ('FIG. 2), stationary contact rod 24, stationary contact 25, moving contact 26, movable contact rod 27, upper rod-end 29, flexible connector 30, through mechanism housing 21 to interrupter terminal 31, through the auxiliary conducting spring rod 33 to mechanism housing 7, and thence through support casting 36 to the right-hand terminal vconnection plate 37.

To eifect the interruption of the load current passing through the circuit-interrupting device 13, there is provided an explosion pot or a substantially closed pressure chamber interrupting element, generally designated by the reference numeral '40, and more clearly shown in FIG. 8 of the drawings.

The load current is extinguished within the interrupting element 40, as hereinafter described, and continued clock- Wise rotation of the main switch blade 10 brings the latter to the fully open dotted position 42 of FIG. 1. The fully open position of the Crank arm 16 is indicated by the dotted lines 43 of FIG. 1. The main switch blade 10 rotates about 'a pivot axis 44, which is disposed adjacent the hinged end of the switch blade 10.

During the closng operation, the rotation of the crank arm 3 in the opposite direction, brings about an actuation of the cam mechanism 6 within cam housing 7 to effect thereby counterclockwise rotative motion of the main switch blade 10. During this closing motion the spring rod 33 makes engagement with the upper interrupter terminal 31, and the tripping stud 14 of main switch blade 10 Strikes a second laterally jutting, actuating rod 46 which is secured to the crank arm 16. The main switch blade `10 forceably drives the crank arm 16 in a clockwise direction to effect snap-closing operation of the contact structure disposed within the pressure chamber 40. This will complete the electrical circuit through the disconnecting switch 1, and further closing movement of the main switch blade 10 will effect reengagement between the contact 11 of switch blade 10 and stationary main switch jaws 12 to bypass the current flow through the interrupting device 13.

The Operating mechanism 20 disposed within the mechanism housing 21 will now ibe explained. AS shown more clearly in FIG. 2 of the drawings, there is provided a crank-arm assembly, generally designated by the reference numeral 49. This Crank-arm assembly 49 is rigidly secured to the drive shaft 17. As mentioned, the drive shaft 17 extends interiorly within the mechanism housing 21, and preferably has a Seal associated therewith to prevent the leakage of arc-extinguishing gas, which is present interiorly of the circuit-interrupting device 13, out axially along the shaft. Such a sealing device may be such as described and claimed in U.S. Patent 2.853,584 issued September 3, 1958, to Chester W. Upton, Jr. and assigned to the assignee of the instant invention.

The crank-arm assembly 49 includes a first crank-plate portion 50 and a second crank-plate portion 51, which are fixedly secured together. A pivot pin 52 pivotally interconnects the first crank plate portion 50 with a link 53. The lower end of the link 53 is pivotally connected, by a pivot pin 54, to a U-shaped lever, generally designated by the reference numeral 55. The legs 56 of the U-shaped lever 55, are slotted, as at 57, vand bear against bearing pins 58, which project inwardly from the inner side walls of the mechan'ism housing 21. 'A Estop bracket plate 59, having an angle port'ion 61, -is fix'edly 'secur'ed by the shaft 17 and one of `the bearin'g pins 58. The angle porti'on 61 of stop bracket plate 59 limits the opening and closing travel of the pivot vpin '52. As shown in FIG. 2, there is provided a ,second U- shap'ed lever, generally designated by'the reference nuin'eral 62. The legs 63 of the second U-shaped lever 62 also 'have slots 64 associated therewith, which bear upon 'the bearing piiis 58. A pivot pin 65, extending through the legs '63 'of the U-shaped lever 62, pivotally 'connect the lever 62 with a channel-shaped lever 66, which is pivotally connected, as at '67, to a channel-shaped lever '68. The chanel-shape'd lever 68 has its upper end pivotally connected, as at 69, to a stationary channelshaped bracket 70, which is sec'ured by bolts, 71 tozboss 'supports 72. The, channel-shaped lever 66, 1n addition, has a pivot pin 7'3, which extends through the rod-end 29 'of movable contact ro'd 27. lutti'ng downwardly from the upper ehd of the mechanism housing 21 is a stop post 74-, -which limits the fully-open travel of the rod-end 29-, s'sl'rown by the dotted line '76 of PIG. 2. I

An overcenter tension spring 75 is in tension, being entended over thepivot pins 54, '65, as shown inVEIG. 2. A push link 77 is pivotally connected, as at 78, to the second cfank-plate portion 51. The pushlink 77 has a slot 79 *disposed therein, through which extends a pin 80, which also extends through one of the legs 63 of the second U-shaped l'ever 62. p

'From the foregoing description of the mechanism 20 and of the 'operation of blade 10, 'it will be apparent that during the 'opening operation, the crank arrn 16 vis rotated in the 'di/rection indicated by the arrow 81 in FIGS. Z 'and 3 vof the drawin'gs. The countercloc-kwise rotation of ``the `craiik-farm 1`6 will correspondiingly effect counter- 'clo'ckwise 'rotati'on 'of the main drive shaft 17, which, through the Crank-plate portion 50, wi'll cause upward movement o`f link '53, and, 'cons'equently, upward move- 'ment 'of the right-hand 'end 'of tension spring 75. When the several parts assurne the position, as indicated in FIG. 3, the overcenter spring mechanism 20 rs overtoggle, and at this point the overcenter spring 75 effects snap-opening travel of the several parts to the fully ,f

'open-circ'uit position, as indicated in F'LG. '4 of the drawihg. Thus, PIG. 4 indicatesthe same position of the mechanism parts "20 'as that findicat'ed by the dotted position-43^of F'IG. 1'.

During the closing operation, as previously descrihed, counterlockwise ro'tative m'o'tion of the tnain switch blade 10 7causes engagemeht between tripping Vstud 14 'and 'actu'ating 'rod V46 'of crank-'arrn 16 to effect clock- Wise rotation of crank-arm 16 in the direction indicated by the arrow 82 'in FG; 5'. During the closin'g operation, z

'the push link 77 moves 'pin down and so forces leve'r 62 towarcl the on-to'ggle position. When the lnrechanisrn parts are in 'the position as indicated in FIG. 5, again the spring 75 is slight'ly past tog'gleand is able to overcorne lthe 'friction 'o'f the parts to effect snap-cl'osing of the movable contact 'rod 27. Thus, FlG. 5 indicates the position of the parts at the instant in which snap-'closing movernentfof the coritactparts occ'urs.

The circuit-i'riterrnpting device '13 will now be descri'led., As more clearly shown in PIG. 2 of the'drawz i'ngs', a weatherproof casing 84 -is provided. Prefefably the casing 84 is of porcelain, but other materials m'ay', 'of

course, b'e used; Encircling the lower end of the por'- celain casing 184 is a Vrh'ounting flange ring 85, which lis cemented, as at 86, to the lower end of the casin-g 84. f

second mounting fiange ring 07 is cemerited, by cement 86, to theV upper end of the -porcelain 'c'asng 84. The casing A84 is secured by mounting bolts '88 to the base plate 89. VAdditional mounting bolts secure 'the upper end of the casig 84 to 'a'ri upper casting 'plate 9.1.

6 The 'casting plate 91 is, in turn, secured by moun'ting bolts 92 to the upper mechanism housing 21.

As previously mentioned, it is desirable to retain an arc-extinguishing gas, such as sulfur hexafluoride gas (SP6) within the interrupting device 13. To prevent leakage, preferably ring gaskets 93-95 are associated with the casing 84 and with the mechanism housing 21, in a'dditicn to the shaft-sealing device for the shaft 17, as previously mentioned.

To as'certain the pressure present within the casing 84, a pressure gauge 96, illustrated in'FIG. 2, is provided. This pressure gauge 96 is visible from ground level by a station attendant. Also a feed valve 97 is provided, which may be connected by a hose connection to an external supply of arc-extinguishi'ng gas, 'such as SP6, not shown.

Disposed longitudinally within the casing 84 is the explosion pot, oTr substantially enclosed pressure chamber 40. As shown, this pressure charnber 40 includes an insulating tube 99, which carries an elongated interrupting4 orifice, lgenerally designate'd by the reference numeral 100, at its upper end. The interrupting orifice 100 has a restricted orifice opening 101 ther'ethrough, through which extends the moving contact rod 27 with very slight clearan'ce. As shown in PIG. 6, the interrupting 'orifice 100 has 'a fiang'e portion 103, which is threa'ded, as at 104, to the upper end of the insulating tube 99. A staking rivet 105 may be provided to bring about va secure attachment. The upper end of the inter'- rutping orifice 100 is fiared, as at 106. The lower end of vthe insulating pressure tube or casing 99 is threaded, as at 107, to secure an apertured metallic base plug 108 fixedly in place. As more fully brought out hereinafter, the metallic apertured base plug functions as 'a valve seat vfor a valve disc 114. The base plug '108 'has apertures 109 theretihrough to permit a fiushing convection flow of gas into the pressure chanrber 40 following arc interruption. I

Plastic rivets 110 fiXedly secure the base plug 108 into position. The base plug 108 is th'read'ed, as at 111, and is also provided with a recess 112, which accommodates spring means 113, which 'serves to bias the valve disc 114 to its upper open position. The valve disc 114 slides over a bushing 115 also threadedly secured to the stationary contact rod support 24.

As shown in FIG. 6, a cup-shaped 'baffie plate 118 is provided 'to protect the normally open valve means 116. The cup-shaped baflie plate l118 has 'a threade'd bore 119, which Vis threaded `onto the stationary Vcontact rod support 24, as shown in PIG. '6.

Apertured ;guide discs 123, Vcomposed of a suitable material, such as polytetrafluoroethyl'ene are provided. This material has the characteristic of resisting 'action from the sulfurghexailuoride gas. The apentur'ed guide discs 123 are disposed within `a recess 124 provided at the lower end of a metallic tube 1625, forrned 'of aluminum, or the like. The apertured guide `discs 123 may be staged into position as shown. 'llhey assist in guiding themovable contact 26 through the orifie opening 101 during the closing operation.

The upper end of the aluminum tube 125 may be threadedly secured, as at 126, to the upper 'casting plate 91', which is preferably provided with aper'tures ,127 to permit intercommunication between the region 128 interiorly of casing 84 and the region 152 'interiorly of mechanism housing 21.

I' The interrupting operation will now be desciihed. As previously mentioned, the overc'enter spring mechanism 20, disposed within mechanism -housing 21, is effe`c= tpive to bring about -snap-opening motion of theflrnovable coi'ltact26 away from vthe stationary contact 25. The

poiitions 'of moving contact 26 'and stationary cont'act 25 are, prefe'rably -faced with` apsilver-tungsten alloy, as provided by the contact tips 278, 38, as shown in PIG. '6. When the moving contact 'rod 26, moves upwardly away from the stationary eonta'ct 25, ah ar'c 133 is drawn within the region 129 interiorly of pressure chamber 40. This will ;build up the pressure therein and imrnediately effect closure of the valve disc 114 over the apertures 109 associated with the normally-open Valve means 116. The pressure will be substantially retained within the region 129 because of the existence of slight clearance between the contact rod 27 and the orifice restriction 101. In effect, the gases will be bottled up within the explosion pot 40. A distinct advantage of the present invention as applied to a load-break disconnecting switch is that the pressure acts upon the end of the moving contact rod 26 and tends to eifect its ejecton from the pressure chamber 40. This will assist the overcenter tension spring 75 in pulling the moving contact rod 27 to its upper fully-open position. As shown in FIG. 8, when the movable contact 26 has just cleared 'the flared portion 106 of interrupting orifice 100, the arc 133, drawn between contacts 25 and 26, will be extinguished by the outflowing gases, as indicated by the arrows 130.

Following extinction of the arm 133, the spring 113 effects reopening of the valve disc 114 to permit a convection flow of fluid back into the arcing chamber 40 in readiness -for a subsequent opening operation. We have found that this is necessary if we wish to make several interruptions within a limited time. It has been discovered from tests that an enclosed chamber without vents will give abut two interruptions one after the other, but will usually fail upon the third trial. By providing the normally-open valve means 116, fresh gas is admitted by convection flow into the arcng chamber 40 following the subsidence of the pressure within the region 129.

'rFIGS. 7 and 9 illustrate a modified interrupting unit or element, generally designated by the reference numeral 135. The interrupting unit 135 includes a pressure chamber, generally designated by the reference numeral 136, within which two series breaks are established. The pressure chamber 136 includes an insulating tube 137, which is threaded at its lower end, as at 138, to secure the normally open valve means 116 into position. The cup-shaped baflle plate 118 is the same as employed heretofore in connection with FIGS. 6 and 8. A considerable portion of the upper end of the insulating tube 137 is threaded, as at 139, to secure into place an intermediate contact guide 141, preferably composed of polytetrafluoroethylene. 'I'he intermediate contact guide 141 has a threaded annular por-ton 142, which is threadedly supported from the casing 137. Apertures 143 are provided through the contact guide 141, as shown. A recess 144 is provided to accommodate a biasing spring 145, w'hich sea-ts at its lower end against the bottom 146 of recess 144. The upper end of compression spring 145 seats against an annular flange portion 147, constituting a part of a movable intermediate contact, generally designated tby the reference numeral 148. An annular recess 150 is provided in the contact guide 141 to accommodate a snap ring 151 composed of polytetrafluoroethylene. The lower end of the intermediate contact 148 is provided with a contact tip 152 of an arcresisting material, such as a silver-tungsten alloy. Likewise, the stationary contact 154 is provided with a contact tip 153 of an arc-resistant material. Supporting the relatively stationary contact 154 from the base plate 89 is a stationary contact support rod 155.

Similarly, the upper end of the intermediate contact 148 is faced with an arc-resistingl alloy, constituting a contact tip 157. The movable contact 159 is also provided with an arc-resisting contact tip 158.

During the opening operation, a pressure-generating arc 161 is established between the stationary contact 154 and the movable intermediate contact 148. Also, an interrupting arc 162 is later established between the intermediate contact 143 and the movable contact 159, following stopping of the intermediate contact 148 at the snap ring 151. It will be noted that the compression spring 145 permits a limited following travel of the intermediate contact 148 with the movable contact rod 159 so that the pressure-generating arc 161 is established first. Subsequently, following halting of the intermediate contact 148 by the snap ring 151, the interrupting arc 162 will be formed.

As illustrated in PIG. 9, the interrupting arc 162 is established longitudinally within an elongated interrupting orifice, generally desgnated by the reference numeral 163, and having an annular supporting flange 164, which is threaded, as at 165, to the upper end of the insulating tube 137. Staking rivets extend through the upper end 166 of the tube 137 as shown in FIG. 9. The interrupting orifice 163 has a restricted orifice opening 167, through which the moving contact rod 159 moves with slight clearance. The upper end of the interrupting orifice 163 is preferably flared, as at 168.

During the opening operation the pressure-generating arc 161 builds up pressure Within the interior region 170 within insulating tube 137 and forces cool gas toward the interrupting arc 162. Following withdrawal of the moving contact rod 159 out of the orifice restriction 167 the pent-up relatively cool gases will be vented out of the region 170 and through the flared opening 168 to effect extinction of the interrupting arc 162. It will be noted that the interrupting arc 162 is drawn through the lengthened orifice 163 so as to be subjected to the very effective flow of relatively cool gases, as they are forced from the pressure chamber 136. As was the case with the pressure chamber 40 of the interrupting device 13 in FIG. 6, the normally-open valve means 116 of the modified interrupting unit will also be closed during the existence of high-pressure conditions within the region 170 internally of the insulating tube 137. Following extinction of the interrupting arc 162, the pressure Will subside within the insulating casing 137, and the compression spring 113 will effect reopening of the valve disc 114.

The arrangement of FIGS. 7 and 9 has the advantage that the arcs 161, 162 are spaced somewhat apart so that relatively cool gas is forced toward the interrupting arc 162.

From the foregoing description, it will be apparent that there is provided a very simple and light weight interrupting unit in which the mass of the movable parts is kept to a minimum. Only a light contact rod 27 of PIG. 6 or 159 of FIG. 7 is employed to be withdrawn from the pressure chamber as a result of actuaton of mechanism 20. As a consequence, the overcenter spring 75 is able to effect very quickly retracton of the light movable contact rod 27 or 159, which may be made of aluminum, out of the pressure chamber 40, or out of the pressure chamber 136.

As mentioned, the pressure within the pressure chamber acts upon the lower end Vof the moving contact rod 27, 159 and tends to efiect the ejection thereof from the pressure chamber 40, 136. This action assists the overcenter tension spring 75 in eifecting quick retracton of the moving contact rod 27, 159. The diameter of the contact rod and the length of the interrupting orifice structures 100, 163 depend upon the current rating of the device and the voltage which is to be interrupted. The interrupting device illustrated in FIG. 6 is particularly adapted for a GOO-ampere 138 kv. rating. For a IZOO-ampere switch, the diameter of the moving contact rod would, of course, be increased. Also, for a lower voltage rating, such as 23 kv., instead of the 138 kv. rating, the dlength of the interrupting orifice 163 would be shortene The explosion pot type of device of the present inventon has a number of advantages over the puffer type of device, as illustrated in the aforesaid Lingal patent, since the weight and mass of the moving parts has been considerably decreased to obtain very high-speed operation.

ananasa 9 I'he `rapidaopenin'g stroke insures that the length of time in which. ,the contacts are subjected to arcing is a minimum. Thus, the contact tips 2,8, 38 do not tendto burn away, nor does hthe po'lytetrafluoroethylene orifice 100 .tcnd tolerode. Moreover, as a result of the speeding up of the contact-rod travel, by utilizing a simple movable contact Vrod v27 and making the interrupter an explosion type, less burning time on the contact tips will provide a longer operatinglife for the interrupting unit. In addition tothis, the design provides for a lower cost interrupter. The dilferences between the 600 and 1200- ampere unitsrconsists only in'changes in the size of the contact tips and size of the orifices. Although the deyice is particularly advantageous, when utilized With sulfur ;hexafluoride gas, other gases, or even air may be mployed.

`When sulfur'hexafluoride gas is employed, it is desir- 'able to utilize hydrogen-free materials for the insulating ,casing,99, 137, for the valve disc 114, for the cup-shaped :baffle 118, for the orifice interrupting structures 100, 163, for thespacing sleeve 160 and for the intermediate contact guide 141'. T his has the advantage that no highly reactive hydrogen-fluoride acids are formed. However, where some other arc-extinguishing gas is employed, other thanV sulfur hexafluoride, ordinary insulating materials, which may contain hydrogen, may be used,

A'lthough there have been shown and described specific interruptingstructures with a showing of their particular ise as applied to a load-break disconnecting switch, it i s to be clearly understood that the same Were merely for theflpurpose ofy illustration, and that changes and modifications may be readily made therein by thosepskilled in the art, without departing from the spirit and scope of, the invention. I

Wevclaim 'as ourhinvention:

1. The combination in a load-break disconnecting switch of a pair of spaced line terminals, movable blade means bridging said pair of spaced line terminals in the closed-circuit position of the switch, an interrupting device associatd with one of the line terminals and having `anV over-center spring mechanism for the operation thereof, a crank-arm extending Aexternally of,the interrupting device and operated by said movable blade means, the interrupting Vdevice including an insulating tubular outer casing ;containing ,an arc-,extinguishing fluid, an inner interrppting 'element including means at least partially of insulatiug `n'raterial defining a pressure chambjer, a relatively stationary contact support rod extending within said tubular outer casing and constituting the sole support for said inner interrupting element, said inner interrupting element being spaced inwardly from the inner walls of said outer tubular casing to provide free space for the circulation of said arc-extinguishing fluid about said inner interrupting element, the interrupting element including a tubular insulating substantially closed pressure casing having an insulating orifice disposed adjacent one end thereof, an apertured metallic base plug secured adjacent the inner end of said support rod and also to the other end of said pressure casing for Vthe support thereof, the inner extremity of said support rod constituting a relatively stationary contact, a movable rodshaped contact actuated by said over-center spring mechanism and rnovable into and out of said insulating orifice into contacting engagement with said relatively stationary contact, the movable contact being cooperable with the relatively stationary contact to establish an arc within the tubular insulating pressure casing, normally-open valve means including said apertured metallic base plug for closing said other end of the pressure casing and adaptable for closing upon a rise of pressure within said casing, the normally open valve means allowing a flow of said arc-extinguishing fluid into the pressure casing in the fully 'closed and fully open-circuit position of the contacts associated With the pressure casing, means electrically connecting said support rod with said one line terminal, means forcing the load current to `flow through .the interrupting device upon disengagement of the movable blade means from said Vone line terminal, and the establishment of pressure within said substantially closed pressure casing during the 'opening operation accelerating the movable rod-shaped contact through the orifice to assist the over-center spring mechanism for faster contact separation speed.

2. A load-break disconnectin'g switch including a pair of spaced line terminals, movable switch blade means bridging said pair of spaced line terminals in the closedcircuit position of the switch, an interrupting device associated with one of the line terminals and having an Operating mechanism associated therewith, the movable switch blade means eifecting actuation of said Operating mechanism during the opening operation, the interrupt- -ing device including an insulating tubular outer casing containing an arc-extinguishing fluid, an inner interrupting element including means at least partially of insulatfing material defining a pressure chamber, a relatively stationary contact support rod extending Within said tubular outer casing and constituting the sole support for said inner intcrrupting element, said inner interrupting element being spaced inwardly from the inner Walls of said outer tubular casing to provide free space for the 'circulation of said arc, exti'nguishing llui'd about said inner interrupting element, the intei'rupting element including' a tubular insulating substantially closed pressure casing having an insulating orifice disposed adjacent one end thereof, an apertured metallic base plug secured advjacent the inner ,end of said support rod and 'also to the other end of said pressure casing for the support thereof, the inner extremity of said support rod constituting a relatively stationary contact, `a movable rod-shaped contact actuated by said Operating mechanism and movable into and out of said insulating orifice into contacting engageme'nt With said relatively stationary contact, the movable contact being coo'perable With the relatively stationary contact to establish an arc within the tubular insulatiug pressure casing, normally-open valve means including said apertured metallic base plug for closing said other end of the pressure casing and adaptable for closing upon a rise of pressure within said casing, the normally open valve means allowing a fiow of said arcextinguishin'g fluid into the pressure casing in the fully closed andfully open-circuit position of the contacts associated with Vthe pressure ,casing, 'means electrically 'connecting said support rod With said one line terminal, means forcing the load current to fiow through the interrupting device upon disengagement of the movable blade means from said one line terminal, and the establishment of pressure within said substantially closed pressure casing during the opening operation accelerating the movable rod-shaped contact through the orifice to assist the Operating mechanism for faster contact separation speed.v

3. The combination in a load-break disconnecting switch of a pair of spaced line terminals, movable blade means bridging said pair of spaced line terminals in the closed-Circuit position of the switch, an interrupting device associated with one of the line terminals and having an over-center spring mechanism for the operation thereof, a crank-arm extending externally of the interrupting device and operated by said movable blade means, the interrupting device including an insulating tubular outer casing containing an arc-extinguishing fluid, an inner interrupting element including means at least partially of insulating material defining a pressure Chamber, a relatively stationary contact support rod extending within said tubular outer casing and constituting the sole support for said inner interrupting element, said inner interreupting element being spaced inwardly from the inner walls of said outer tubular casing to provide free space for the circulation of said arc-extinguishing fluid about said inner interrupting element, the interrupting element including a tubular insulating substantially closed pressure casing having an insulating orifice disposed adjacent one end thereof, an apertured metallic base plug secured adjacent the inner end of said support rod and also to the other end of said pressure casing for the support thereof, the inner extrernity of said support rod constituting a relatively stationary contact, an intermediate contact biased away from said relatively stationary contact and separable therefrom to establish a pressure-generating arc within said substantially closed pressure casing, a movable rod-shaped contact actuated by the over-center spring mechanism and movable into and out of said insulating orifice into contacting engagement with the intermediate contact, the separation between the intermediate and movable rod-shaped contact establishing an interrupting arc adjacent said orifice and in series relation with said pressure-generating arc, normally-open valve means including said apertured metallic base plug for closing said other end of the pressure casing and adaptable for closing upon a rise of pressure within said casing, the normally open valve means allowing a flow of said arc-extinguishing fluid into the pressure casing in the fully closed and fully open-Circuit position of the contacts associated With the pressure casing, means electrically connecting said support rod with said one line terminal, means forcing the load current to flow through the interrupting device upon disengagement of the movable blade means from said one line terminal, and the establishment of pressure within said substantially closed pressure casing during the opening operation accelerating the movable rod-shaped contact through the orifice to assist the over-center spring mechanism for faster contact separation speed.

4. A load-breaking disconnecting switch including a pair of spaced line terminals, movable switch blade means bridging said pair of spaced line terminals in the closedcircuit position of the switch, an interrupting device associated with one of the line terminals and having an Operating mechanism associated therewith, the movable switch blade means etfecting actuation of said Operating mechanism during the opening operation, the interrupting device including an insulating tubular outer casing containing an arc-extinguishing fluid, an inner interrupting element including means at least partially of insulating material defining a pressure chamber, a relatively stationary contact support rod extending Within said tubular outer casing and constituting the sole support for said inner interrupting element, said inner interrupting element being spaced inwardly from the inner Walls of said outer tubular casing to provide free space for the circulation of said arc-extinguishing fluid about said inner interrupting element, the interrupting element including a tubular insulating substantially closed pressure casing having an insulating orifice disposed adjacent one end thereof, an apertured metallic base plug secured adjacent the inner end of said support rod and also to the other end of said pressure casing for the support thereof, the inner extremity of said support rod constituting a relatively stationary contact, an intermediate contact biased away from said relatively stationary contact and separable therefrom to establish a pressure-generating arc Within said substantially closed pressure casing, a movable rod-shaped contact actuated by the Operating mechanism and movable into and out of said insulating orifice into contacting engagement With the intermediate contact, the separation between the intermediate and movable rod-shaped contact establishing an interrupting arc adjacent said orifice and in series relation with said pressure-generating are, normally open Valve means including said apertured metallic base plug for closing said other end of the pressure casing and adaptable for closing upon a rise of pressure within said casing, the normally open valve means allowing a flow of said arc-extinguishing fluid into the pressure casing in the fully closed and fully open circuit position of the contacts associated with the pressure casing, means electrically connecting said support rod With said one line terminal, means forcing the load current to flow through the interrupting device upon disengagement of the movable blade means from said one line terminal, and the establishment of pressure within said substantiallyV closed pressure casing during the opening operation accelerating the movable rod-shaped contact through the orifice to assist the operating m-echanisrn for high speed contact separation.

References Cited in the file of this patent UNITED STATES PATENTS 1,784,303 Millikan et al. Dec. 9, 1930 2,13%,323 Hilliard Nov. 29, 1938 2,4l2,897 MacNeill Dec. 17, 1946 2,420,889 Leeds et` al. May 20, 1947 2,606,262 Bartlett Aug. 5, 1952 2,757,261 Lingal et al. July 31, 1956 2,91 1,506 Owens Nov. 3, 1959

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