US2575730A - Circuit breaker - Google Patents

Description

J. SANDIN F AL Nov. 20, 1951 CIRCUIT BREAKER 3 Sheets-Sheet 2 Filed March 13, 1947 N0V- 20, 1951 J. SANDIN ETAL 2,575,730

CIRCUIT BREAKER Filed March 13, 1947 s sheets-sheet 5 Patented Nov. 20, 1,951

CIRCUIT BREAKER Jerome Sandin, Forest Hills, and Herbert L.

Rawlins, Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 13, 1947, Serial N 0. 734,444

9 Claims.

This invention relates to circuit breakers in general, and more particularly to arc extinguishing structures therefor.

A general object of our invention is to provide an improved circuit breaker of simplified construction and relatively few parts which may be easily disassembled to inspect the several component parts thereof.

Another object is to provide an improved circuit interrupter of the foregoing type which will have an increased interrupting capacity as a result of improved cooling means for the arc gases which we provide with our invention.

Still a further object is to provide an improved circuit breaker in which improved interlocking means are provided between the several parts.

Another object is to provide an improved circuit breaker of the air-break type in Which an improved baie construction is employed in conjunction with the spaced plate extinguishing structure to more effectively deionize the arc gases and prevent restriking across the edges of the plates than has been obtained heretofore.

Another object is to provide an improved housing for an arc extinguishing structure of the spaced plate type in which, by the provision of cooperating grooves on the interior walls thereof. improved means are provided for holding and positioning the spaced plates in proper place. In the same connection it is desired to facilitate manufacturing of the devices by the use of such improved housing construction.

Another object is to provide an improved plate construction for arc extinguishing structures of the spaced plate type to more effectively absorb the thermal energy of the arc gases to intensify the cooling thereof to thereby facilitate dielectric establishment andconsequent arc extinction.

Further objects and advantages will readily become apparent upon reading the following specification taken in conjunction with the drawings in which:

Figure 1 is substantially a vertical sectional view through an improved arc extinguishing arc chute'structure showing our invention, taken on the line I-I of Fig. 2, the contacts being shown in the closed circuit position;

vFig. 2 is a vertical sectional view taken along the line lI-II of Fig. 1, the contact structure being omitted for the purpose of clarity;

Fig. 3 is a vertical sectional view through the arc chute housing to show the improved slot construction provided to hold the several plates in spaced relationship;

Fig. 4 is a fragmentary, perspective view of a portion of the arc chute to more clearly indicate that the two sets of slots are in two different substantially parallel planes;

Fig. 5 is an end view of the baie member which appears looking toward the left in Fig. 1;

Fig. 6 is a side elevational view of the other end of the baille member, that is, looking toward the right in Fig. 1; and

Figs. '7 to 14 inclusive are end and side elevational views of the several conducting platev members used in our improved arc extinguishing structure.

Our invention is particularly concerned, although not solely applicable to, arc extinguishing structures of the spaced conducting plate type, the theory and operation of which are set forth in U. S. Patent No. 1,932,690 which issued October 24, 1933, to Joseph Slepian, U. S. Patent No. 1,963,643 which issued June 19, 1934, to Maurice W. Brainard and Benjamin P. Baker and U. S. Patent No, 2,147,419 which issued February 14, 1939, to Benjamin P. Baker, all of the aforesaid patents being assigned to the assignee of the instant application. Since the theory and fundamental operation of the spaced plate type of arc extinguishing device are set forth in these three patents, it is consequently believed that a detailed picture of the theory of the operation is unnecessary for a full understanding of our invention.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference character I designates an insulating base plate upon which the several parts of the circuit breaker 2 may be mounted. Generally speaking, the circuit breaker 2 includes an arc extinguishing deviceV 3 and separable contact structure i operable to establish an arc. The contact structure 4 includes a stationary contact 5 having an arc resisting tip portion 6 and an arcing horn 'l composed of magnetic material. The stationary contact 5 is secured to the base plate I by a stud bolt S which passes through the plate I, and also secures xedly in place a terminal strap 9.

Cooperating with the arc resisting tip portion 6 is a movable arc resisting tip portion Iii secured to the movable contact II, the latter having a diagonally extending movable arc horn I2. The

movable contact I I is secured by a pair of screwsv i3 to a movable contact arm I4, the latter being pivotally mounted by a pin I5 to a metallic frame I6. The frame I6 is pivotally mounted at engagement in the closed circuit position of the circuit breaker, as shown in Fig. 1, by a compression spring I9, one end of which is seated in a recess formed in the base plate I. The left hand end of the compression spring I9, as viewed in Fig. 1, engages the lower end 2I of the movable contact arm I4 as shown. A conducting strap 22 is secured at one end to the contact arm I4 and the other or lower end 23 thereof preferably extends through an electro-responsive trip device not shown. Y

Thus in the closed circuit position of the breaker, as shown in Fig. 11, the circuit there--4 through includes terminal strap 9, stationary contact 5, movable contact Il, conducting movable contact arm I4, and through conducting strap 22 to the electroresponsive device, not shown.

' To cause actuation of the movable contact arm I4 to the open circuit position, we provide an insulating operating rod 24 which is pivotally mounted. byv the pin I5 to the movable contact arm i4. An aperture 25 is provided through the left hand end of the operating. rod 24 to permit the linkage thereto of an` operating mechanism, which. may be of any suitable type.v

It will be apparentthat upon opening .motion of thev operating rodV 24,- an arc will. be initially established between the arores'sting tip portions 6, I0. Because off the loop circuit provided, the established. arc will tend to bow upwardly as indicated. by the dotted line 28', the dotted line 29 indicating the almost full open position of the movable arc yhorn l2. This elongated are 28 will be attracted and moved upwardly into the arc extinguishing device 3 to effect the extinction thereof.

VThe are extinguishing device 3 will now be described` The arc extinguishing structure 3l includes a plurality of spaced slotted magnetic plates 30., the configuration of which is Vmore clearly shown in Figs. 9 and 1-0. Each steel plate 36' a slot or notch 3-Iv formed therein, extending upwardly from` 'the lower edge A32 of the plate, thus forming two downwardly extending legs 33.

The notchor Vslot 3I comes to an apex 34 adja- 4 cent `the upper 'end ef the plate 3i). Near the upper end of the plate are two recesses Y35, the 4functionof which will be more apparent hereinafter. Since the plates 38 are of ferrous material, in this instance steel, the magnetic reac tion between the arc 228 and themagneti'c plates 36'r is such as to attract or draw the a-rc 28 up- Wardly within the notch 3LI towards the `apex 34 thereof.

This movement of the arc 28 will restrict it at its outer periphery' due to the convergence `of the Walls defining the slots 3|. Thus this upward movement of the arc 28 toward the closed end of the slot or notch '3| restricts the arc core and increases the arc voltage. The increase in the arc voltage rises to the point where the arc 28 is subdivided into a plurality of relatively short arcsV extending originally between fthe 'spaced magnetic plates 30. Y

yThe spaced magnetic plates 30 constitute one type of conducting platel which. we employ ink our arc extinguishing device '3. The other type is herein designated by the reference character 316 and is shown more clearly in Figs. V'7 vand 8. The several conducting plates 36 are formed of a conducting material which .has a higher thermal conductivity than the .ferrous .plates 36. Pre-ferably we employ copper .for the short plates 36, copper having a highertherm'al conductance and Capacity. `Other metals of.y'approximatehf the same cost or less could be used, but they would not be as effective in cooling the arc gases.

Referring to Figs. 7 and 8 it will be observed that each of the short copper plates has two 5 apertures 38 formed therein within two leg portions 39, the latter being bridged by a 'bight portion 48'. By the addition of copper plates 36 between the steel plates 33, the cooling and neutralizing of the ionized gas is considerably increased. It has been noted during tests that the several short arcs between the plates 3D impinge and travel a short distance on the copper plates 36, thereby being further subdivided. This means increased arc voltage due to the additional short arcs established between the copper plates 36. As a result of these advantages, there is less outward .disturbance in the form of flame and report than when only the steel plates 30 are used.

Referring to Figs. 2 to 4 inclusive, and particularly to Fig. 4., it will be noted that we have provided two sets of interiorly disposed slots in different substantially parallel planes on the opposed side walls ft2 of the aro chute housing or casing 43. Preferably the casing 43 is formed by a hot molding yprocess from a suitable molding material. Fig. 4 more clearly shows that .the upper set of slots 44 extend Vto a depth which is deeper into the interior of the side walls 42 than the depth of the lower set of slots 45. Thus the plates 3U., having a more narrow width than the plates 35, freely slide between the ridges 46 of the slots 44'. However, the plates Sil rare yet of such-width that the ridges lil of the lower set of slots 45 hold them in the proper spaced position. Thus the,` vassembly of the plates 38 within `the. arc .chute housing d3 is facilitated by the slot construction which we employ. The plates 36; not touching anyl ofy the ridges 46 of the upper slots 44 easily move downwardly between the ridges 47 of the lower Vslots 45 until the lower edges 32 of the plates 30 strike the lower ends 48 of the lower set of slots 45 as more clearly shown in Fig. 3.

The short copper plates 36 are so wide as to be held .in position by the ridges et of the upper set of slots 44 so that the lower edges 49 of the plates 36 `come to rest at the lower ends 56 of the upper set of slots 44. It will be noted that 50 the Width of the short copper plates 35 is such that they V.never come into engagement with the lower set of slots 45. This results since the width between the opposed planes 5i of the side walls 42 of the arc chute housing 43 is less than the width of the short copper plates 35.

"From the foregoing description of our improved slot construction, it will be apparent that we have provided two sets of interiorly disposed slots o1' grooves disposed in different vertical substantially G0 parallel pianesk in the rectangularly-shaped housing means 43. This improved slot construction results in speedy assembly of the plate structure by workmen in the assembly processes without chance of placing the vwrong plate in an improper slot. Thus plates 3d, being Vof a width less than the distance between the opposed ridges i6 of the upper slots 44 are iirst placed into the lower set of slots 45. Following this 'operation the short copper plates 36 are positioned between 7o the plates 3b' in the upper set of slots 44 being held therein by the ridges 45 of the upper set of slots or grooves d. Fig. 2 rshows the assembled plate structure following insertion of the several plates into the two sets of slotsli-, 45.

7,5 It wii'lbe noted that to accommodate the full asunto provided a modied steel plate 53, the conguration of which is more clearly shown in Figs. 13 and 14. The plate 53 has a recess 54 formed therein to accommodate the moving arc horn i2 in providing proper clearance therefor in the full open position of the breaker. This is only partly shown by the dotted lines of Fig. l. The plate 53 also has the notches or recesses 35 provided in the side walls 55 thereof. The upper edge 56 of the plate 53 has small notches or recesses 5l provided therein to permit the passage of arc gases across the top of the plate 53 to take advantage of the venting means provided at the left hand end 58 of the baille member 53, more fully described hereinafter.

Also the plate 53 has latch or hook portions 5G integrally formed therewith to hook or latch onto the left hand end of the baille member 59.

The extreme right end plate 6I of the arc extinguishing device 3, as viewed in Fig. 1, has a configuration more clearly shown in Figs. 11 and 12. This plate i5 i, as was the case with the plates 30, 53, is formed of steel. It has an enlarged cutout portion S2 to accommodate the magnetic stationary arc horn l. It also has the recesses 35 and hook or latch portions 59. Further, it has the recesses or notches 5l' as was the case with the plate 53. The hook portions 5i! hook onto the right hand end 63 of the baille member 59 as viewed in Fig. 1. Thus, two end plates 53, 6I of the spaced plate arc extinguishing device 3 hook or latch onto the opposed ends 58, 63 of the baille member 59.

Our improved baille member 59 has a construction more clearly apparent from an examination of Figs. 1, 2, 5 and 6. Referring to Fig. 5, which shows the right hand end 53 of the baille member 59, it' will be noted that we have provided recessed portions 54 grooved into the end of the baille 53. Noting Fig. 5 in conjunction with Fig. 11, it will be apparent that the hook portions 60 of the plate 6i may extend into the recessed or latched portions 54 formed in the end 53 of the baille member 59. Thus, when the hook portions 60 of plate 6i are disposed in the recessed portions 64, as more clearly-shown in Fig. l, the baffle member 59 has its right hand end 63 rigidly held in place by the end iron plate 5l of the arc extinguishing device 3.

Similarly, referring to Fig. 6, the left hand end 58 of the baille member 59 has recessed portions 65 formed in the end 53 thereof to permit engagement therewith of the hook portions 5B of the left hand steel plate 53 of the arc extinguishing structure 3. Consequently the plate 53 firmly latches and holds the end 5S of the baille member 59 in position as shown in Fig. l. The baille member 59 is hence solely held in position by the hook portions 60 of the two plates 53, 5l. No other means is necessary for maintaining the baille member 59 in position. n

AAs shown in Fig. l, vent passages 55 are provided inthe end 58 of the baille member 59 oommunicating with the recessed portions E5. These vent passages 55 permit exit of the are gases out of the casing 43 through the left hand end 59 of the baille member 59. Likewise small vent passages 61, more clearly shown in Figs. 1 and 5, are provided in the end 63 of the baille member 59 to facilitate venting of the arc gases adjacent the right hand end 63 of the baille member 59.

Disposed along the length of the baille member 59 are formed a plurality of rectangularly-shaped vent slots 98, the configuration of which is more readily apparent from a study of Figs. l and 2.`

baille in place.

Between adjacent rectangularly-shaped vent slots 68 are transverse baille barriers 69, which preferably are in substantially the same vertical plane as the plates 39, 53 and 6l. Thus the short copper plates 36 are disposed in vertical planes which are intermediate the planes of the baille barriers 69. This construction lends itself readily tov facilitating the venting of the arc gases between the short copper plates 39 and the adjacently op- -posed steel plates 33 as indicated by the arrows 19 of Fig. l.

Following entrance of the steel plates and copper plates into the proper position within the two sets of slots 44, 45, the recesses 35 of the plates 3U, 53 and 6i align with the apertures 38 of the short copper plates 36 so that two insulating tubes (Fig. 2) may be forced laterally into the arc extinguishing device 3 from the right hand end thereof as viewed in Fig. l. This operation is easily done and. it locks all of the plates and furthermore the baille 59 itself into a secure position within the casing or housing means 43. In other words, the tubes il lock the plates in place, and the end plates 53, 5i latch or lock the Following insertion of the insulating tubes il within the device 3, two stud bolts l2 are inserted through the tubes 'il from the left hand end of the arc extinguishing device 3 as viewed in Fig. l. The right hand ends 73 of the stud bolts l2 are threaded and are threadedly secured into the threaded sleeves 'i4 molded within the base plate l. Thus the stud bolt 'l2 threadedly attaches the arc extinguishing device 3 rigidly in place on the oase plate i of the circuit breaker.

To disassemble the device it is merely necessary to unscrew the stud bolts l2 from their engagement with the threaded sleeves lil, whereupon, the entire arc extinguishing device 5 may be removed toward the left away from the base plate I. Following removal of the arc extinguishing device 3 from the base plate i, the stud bolts l2 may easily be removed from the insulating tubes li. tinue to hold the device in its assembled state. Now the tubes il may be removed from the right of the extinguisher 3, whereupon all of the plates 35, 35, 53 and 5l, together with the baille member 5.9 will loosely fall out of the housing 43 upon turning the same upside down.

The foregoing illustrates how the device may be readily removed from the base plate l and the component parts thereof removed for inspection or replacement. The assembling oi the device has already been described above.

The above description of our invention shows that it incorporates an arc chute of the V-shaped steel plate type together with copper plates for additional cooling and deionizing of the arc gases, a new type of bale member 59 and a simple interlocking means to hold the various component parts together. We have provided a simple and cheap means to interlock the steel and copper grid plates 39, 35 and mufiler 59 to the insulating casing 53. The slotted insulating baille member 59 is located. so that its transverse barriers 39 come against the top ends of the steel and copper plates 39, 35 and thus interpose relatively long insulating slots 58 between the top of the plates and the atmosphere above the arc chute. The barriers 59 are parallel with the grid plates 35, each of which has a barrier against it.

The arc drawn between the two contacts 5, H is forced lagainst the V-shaped steel plates 3U toward the apex 34 thereof by the magnetic field set up around the arc and the steel plates. v This At this point the tubes il concauses. the are to break into a` seriesV of' short arcs:

which areiforcedtowards the. magnetic center of the plates. The increased arc voltage` due to the drop across the various cathode and anode ter-f minals and the cooling and neutralizing of the hot ionized arc gas by the steel plate extinguishes the arc.

By having the barriers tv of the mufler 59 against the top ends of the grid plates 3d, the part of the arc gas which has not been deionized by the plates is prevented from arcing across the top of the grid plates. Consequently the reestablishment of a single long arc across the tops of the grid plates in place of the plurality oi short serially related arcs is prevented by the posi tioning of the baflie member or muffler 59 so closely adjacent the top ends of the grid plates'.

The arc gas when passing through the vent slots 58 of the baille member 59, which is madel of melamine, burns some of the melamine and the resultant gas is of such nature that it neutralizes some of the ionized gas. rIhis helps to prevent flash-over to ground from the topV of the arc chute.

The placing of a muler with narrow insulated slots between the top of the grid plates and the atmosphere above the chute, permits the gro-unded steel enclosure of the circuit breaker to be placed closer to the arc chutes of several poles. Less distance between the arc chutes and the steel enclosure means that a smaller enclosure can be used. lIhe cooling and neutralizing of the arc gas as described in the preceding paragraphs also permits further decrease in thisdistance. It is well known that arcs cannot be maintained in insulating slots of the proper width and length.

Although we have shown and described a specie structure, it is to be clearly understood that the same was merely for the purpose of illustra tion, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

We claim asrour invention:

4 l. In a circuit interrupter, a housing having a vent opening therefrom, means for establishing an arc, means for extinguishing the are within the housing including a plurality of spaced plates,I means for marring the. arc against the plates, baule means disposed in the vent opening for cooling and deionizing the arc gases passing out of the housing through the vent opening, and at least one of the plates having a latch portion at the end thereof remote. from the arc establishing means cooperating with a cooperating latch portion on the baffle means to hold the latter in position.

2. In an air-break type of circuit interrupter, a plurality of spaced plates, means for establishing an arc and moving the established arc into engagement with the spaced plates, a housing having a removable baille member associated therewith, and two of the spaced plates having hook portions formed thereon to hook and hold the bauleV member in position.

3. In a circuit interruptor, a housing having a vent opening therefrom, a removable baule member positioned within the vent opening during operation of the interrupter, removable eX- tinguishing means disposed within the housing, and latching means associated with the removable extinguishing means for latching and holding the baille member in position within the vent opening.

4. In a circuit interrupter, a housing having a vent opening therefrom, a removable baille.

memberV positioned within the vent openingl during operationI of the interrupter, removable exoper-ation of the interruptor, a vent opening leading out of the casing, a baie member of substantial thickness disposed within the vent opening and making abutting engagement with the edges of the plates nearest the vent opening to prevent establishment of an arc across the plates, and latching means associated with one or more of the plates to latch the balilev member in position.

6. In a circuit interruptor, means for establishing an are, a casing, removable arc extinguishing means disposed within the casing including a plurality of spacedv removable plates, the are moving into engagement with the plates during the opening operation of the interruptor, a vent opening leading out of the casing, a baille mem 'oer oi substantial thickness disposed within thevent opening and making abutting engagement with the edges of the plates nearest the vent opening to prevent establishment of an arcv across the plates, latching means associated with one or more of the plates to latch the baille mem--l ber in position, and holding means independently of the latching means for maintaining the plates in position.

7. A circuit interruptor including means for establishing an arc, extinguishing means for the are including a plurality of spaced plates of at 5 least two diierent types of different widths,

spaced relationship including a pair of opposed wall members, the inner walls of both wall members having two sets of slots provided on the substantially rectangularly-shaped housing composed of insulating material, means for establishing an arc, arc extinguishing means including a plurality of spaced plates of at least two olifferent types of different widths positioned within the housing for extinguishing the arc, two sets of grooves provided on the inner surface on each of the two side walls in different planes for maintaining the two diuerent types of plates in spaced relationship, the two sets of grooves being cut diierent depths into the interior of the inner surfaces of the two side walls, the narrower width of plate clearing the ridges of the deeper set of grooves, and the ridges of the shallower set of grooves being formed on the plane of the ridges of the deeper set of grooves.

9. An arc extinguishing means including 'lrlspaced plategextingushng Structure, the spaced.

housing means for positioning the plates in f plate extinguishing structure including at least two diierent types of plates of different widths, casing means for maintaining some of the plates in xed spaced relationship, the two opposed walls of the casing means each having two sets of interiorly disposed grooves in different planes, one type of plate of one width disposed in one set of grooves and the other type of plate of the other width being disposed in the other set of grooves, the two sets of grooves extending different depths into the interior of the inner walls of the two opposed walls, the narrower width of plate clearing the ridges of the deeper set of grooves, and the ridges of the shallower set of grooves being formed on the plane of the ridges of the deeper set of grooves.

J EROME'` SANDIN.

HERBERT L. RAWLINS.

10 REFERENCES CITED The following references are of record in the fie of this patent:

UNITED STATES PATENTS Number Name Date 1,963,643 Brainard June 19, 1934 2,133,158 Ver Planck et a1. Oct. 11, 1938 2,293,513 Linde Aug. 18, 1942 2,337,949 Walle Dec. 28, 1943 2,353,729 Jensen July 18, 1944 2,416,164 Ellis et a1. Feb. 18, 1947 2,445,199 Spiro July 13, 1948 FOREIGN PATENTS Number Country Date 344,988 Great Britain Jan. 7, 1930

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