US1932090A - Circuit breaker - Google Patents

Description

Oct. 24, 1933.

.1. SLEPIAN CIRCUIT BREAKER Filed April 29, 1927 2 Sheets-Sheet 1 Fly. 1.

INVENTOR Joseph Slepian I WITNESSES: RQZMM ATT'ORNEY 2 Sheets-Sheet 2 INVENTOR" Joseph Slepmn ATTbR EY J. SLEPIAN cmcuxw BREAKER Oct; 24, 1933.

Filed April 29, 1927 I I 1 l/ 1 r WITNESSES:

Patented Oct. 24, 1933 "'PArEur OFFICE.

CIRCUIT Joseph Slep Westinghouse El mum ectrlc &

Pa, to mnhcturlnlconpany, a corporation of I Application April :9, 1m. Serial No. 187,451 11 Claims. (cl. zoo-144) My invention relates to circuit breakers, and

particularly to are extinguishing devices therefor. One object or my invention is to provide means for interrupting the flow of electricity through gaseous media. Another objector my invention is to provide a circuit breaker provided with an arc-interrupting device capable of opening highvoltage large current arcs in air or .in gases, without recourse to oil or other arc-quenching media. Some or the aspects of my invention are, however, applicable in connection with devices for opening circuits of lower power and to a variety of other uses.

The principal field for immediate application of my invention is in connection with alternatingcurrent circuit breakers and I shall, therefore, describe an embodiment of my invention as applied to such circuit breakers, without in any way intending to restrict the scope or my invention, except as indicated in the appended claims. According to my invention,.the arc incident to the opening or a circuit is driven into a deionizing structure comprising a series of spaced metallic plates having tapering notches aligned to form a v-shaped groove. when forced into the apex of this groove, there is a large deionizing action, and the arc is extinguished as the current passes through zero.

Ey thus rapidly eliminating the ionisation that would otherwise maintain the electrical conductivity or the path until the line voltage had risen sumciently to reignite the arc, current now through the circuit breaker is eflectivelyptopped.

Other objects of my invention will become apparent upon reading the rollowing specification.

, In general, my invention comprises the features or construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the claims.

For a more complete understanding of the nature and objects of my invention, reference should be had to the following detailed description taken in connection with theaccompam drawings, in which,

Fig. 1 .is a general race view or a contaotor adapted for controlling circuits comprising three line conductors and which embodies my invention. Fig. 2 is a sectional view of the main arcing contacts and the deionizing chamber associated with one supply line or contactor,-

Fig. 3 is a rear view of the deionizing chamber, Fig. 4 is a top view of the deionizing chamber,

and,

Pig. Sisasectionalvlewonflaelinesindicated by V-V in Fig. 2.

Referring to the drawing my contactor comprises a base 1 of insulating-material ries stationary members 2 or each pair or principal contact members, the members 2 being bolted directly tothebaee 1. Eachstationarymembcr 2 is provided with a suitable terminal stud 3 to which supply line connections may be made in the ordinary manner or the art. 05

lhe contacts 2 have a peculiar structure which will be more fully described in connection with the blowout magnets associated therewith. The movable member 4' or eachpair of contacts is a supported on the free end or a contact support 5, the other end of which is fixed to a cross bar on trunnions 'I slotted recess 9 near the end or the member 5 and, when the contactor is open, is loosely held in place by a stud l0. Stud 10 passes through a hole in the contact support 5 and also passes, with a loose ht, through another hole near one end or the 2, when the breaker by flexible leads 13, the stationary are attached to suitable studs 14, 15 and 16 tired in the base member 1. connection of the loadline conductorsmaybe madedirectlytothestuds 14, 15 and 16, if desired. Alternatively, overload relays or known type may be madeconnectedtoanydtheeestuds; antitdesired,someoithesereiaysmaybemoimtedonthe ticnedtobeattractedbyamagneticcorelewhu the latter is excited by current supplied to the solenoid l9'asaconsequence otcloeumotanauxillery control circuit 20 appertaining thereto. 'lhiseontrolcircuitmayderlveenergylromany convenient eourcaror exampIeJr-om twoorthe llneterminaletudsaandmaymcludemeerlee no of an inch thick and they ,Iachstatio'nary contactor 2 thebase but their .of a reentrant notch toward the upper end of the shape.

housing 21, these V-shaped notches aline to'formof relay contacts by which it may be desired to control the opening and closing of this contact. Such relays are well-known in the art and constitute no part of this invention.

When the solenoid 19 is energized by completion of the control circuit, the lever arm 17 is attracted towardthe core 18; the cross bar 8 is turned on its trunnion 7 and thereby moves contact members 4 into a ement with contact members 2, thus closing the line circuits. The lever arm 17 is so disposed relative to the trunv nions supporting the cross bar 6 that the weight of the lever arm 1'! tends to soturn the cross bar 6 as to move contacts 4 backward and away from contacts 2. Upon interruption of the control-circuit 20 the weight of lever arm 1! thus separates contacts 2 and 4 thereby opening the contactor.

The foregoing describes the general structure of my contactor and its operating mechanism. In what immediately follows the deionizing structure which constitutes a principal feature of my invention will be described.

Each pair of contacts 2 and 4 is supported in a chamber 21 shown in detail in Figs. 2 to 5, inclusive. These chambers have side walls 22 and end walls 23 of a refractory insulating material; but are open at the top and botom. This chamber 21 is hereafter referred to as the deionizing chamber, and when the contacts 2 and 4 open, the re-. sulting arc is drawn within the lower. half of chamber 21. Fig; 2 shows chamber 21 in the upright position it will have when the contactor ,ls installed on an ordinary switchboard, and the words upper" and lower" herein refer to such tion.

In the upper half of the chamber 21 are positioned a series of vertical metal plates 24, the

configuration of each of which is indicated by Fig. These plates may be of copp r about may be spaced about 5 of an inch apart between their adjacent faces. They are fixed inthe walls of the chamber 21 by the small projections 25 fitting in corresponding socketsinthose walls. This series of plates extends across the entire opening in the upper end more fully appear hereinafter.

is formed in what roughly described as a U-shape and as is in- Fig. 2. The arm of the U farthesti'rom the base'plate 1 extends into the chamber 21 in close 'proxlmity'to the innermost member of the .series of metal plates 24.

The end wall of the chamber 21 farther from Fig. 2 The contour oi' the upper end of plates 24 is with sides curving together to a rounded apex about-two-thirds of the way plate.

Figs. 3 and 5' show the generaloutlines of this notchwhich may be roughly described as of V- Whenthe plates 24 are mounted in the a V-shapedgroove into which the driven to aid in m e quenching it. x

. the arc concentrates in a lower edge is in the form The chamber 21 is held snugly embraced between the arms of aniron plate 27 of U-shape, the chamber 21 being, in reality, made up of two symmetrical halves of insulating material held together bythe pressure of the arms of the members 2'1 between whichthey are pushed with a friction fit. This is shown more plainly in Figs. 4 and 5, while P18. 2 shows the shape of the side plates constituting the arms of the u which have their upper edges near the level of the apex of the V-shaped groove above mentioned, and their lower edges slightly above the bottom of the arcing chamber. This iron plate member 2'! acts as a blowout magnet for the are drawn between contacts 2 and 4, since a magnetic field is set up transverse to the deionizing chamber in consequence of the magneto-motive force due to current flowing in the arcing contacts 2 and 4, as will be explained more fully below.

The deionizingchamber 21 is held in position relative to the contacts 2 and 4 by a clip 28 which is adapted to slip with a spring fit over the contact member 2, as will be apparent from an inspection of Fig. 2.

As has been mentioned, formed. in substantially a U-shape. One arm 29 of the U is afiixed tothe base plate 1 by stud 4 while the other arm 30 of the U stands inclined *ata slight angle to the face of the base plate 1,

but spaced away from it. The U-shaped iron. plate 27 thus loops around the arm 30 of contact member 2; arm 30 may be termed an arcing horn. Similarly the end 31 of contact member 4 is bent to substantially a right angle andmembers. 2 and contact member 2 is 4 are so positioned on their supports. that when the contactor is closed, contact is made between them at the lower end of their are horns 30 and 31. Fig. 2 illustrates this construction.

In consequence of the above-described arrangement, when the contactor opens under load the movement of the contact member 3 away from the contact member 2 draws an are between the lower ends of their respective arc horns 30 and 31. The fiow of this current in the arm 30 of member 2 exerts a magneto-motive force to set 0 up in the iron plate-27 a flux which crosses the deionizing chamber 21 in a direction perpendicular to the path of the are being drawn between the contact members 2 and 4. This magnetic field reacts. in accordance with well-known electromagnetic lawsv to drive the arc upward 'in the chamber 21 toward the plates 24 and into the V-shaped groove formed by the contours of their lower ends. The proximity of these relatively cold metal plates tends to diminish the cross-sectional area of the are, probably by rapid I extraction of energy in the form of heat and the discharging of ions present in the peripheral layers of the arc. At any rate, it is a fact that smaller volume and its voltage-gradient rises. This causes the current to fall to zero more rapidly than it otherwise would. For currents at nearly 100% power factor, the current will reach 'zero when the generated voltage is less than the voltage required to maintain the arc in the groove. Then the current will stay zero until the generated voltage following its normal sine wave rises to a value again suincient to maintain an arc in'the groove. This, -however, takes so long a time that during its course the conductivity of the air in the groove is completely lost, and the arc does not reignite. If, however, the power factor of the current is nearly zero when the current reaches zero the voltage across the switch rises almost immediately 150 tions, if the plates by .a winding in series would still be-within are between the plates after the current layer on the surface plays to the peak value of the generated voltage, which tends to reignite the arc in the opposite sense. The time for this voltage rise depends on the inductance and capacity of the leads and apparatus to which the switch is connected and is usually of the order of m second. Because this time is so short, it is necessarythat the ions be removed from the arc. with great rapidity if.

reignition is to beprev'nted. The very close proximity of all parts of the arc in the slot to the metal plates causes a very rapid deionization, because all the ions which reach the plates are thereby discharged. The narrower the. slot in which the arc finds itself at the time of current zero, the more rapid will be the deionization, and

the higher the voltage which may be interrupted at zero power factor without arc reignition.

. Under normal operating conditions the strength'of the magnetic field of magnet 2"l is of such magnitude in relation to the current and assemblage of plates as to force the arc stream up to the apex of the groove but not onto the plates 24., and consequentlyits extinction occurs within the confines of the groove.

If, however, the magnetic field is made too strong, the arc will bedrivendnto. the spaces between the metal plates 24, and .caused to form a series of short arcs, each short arc having terminals on pairs of plates 24. Under these condiarc...terminals, the arcs must be moved very rapidly along the plates 24, and a m etic field sufliciently strong to accomplish this should be provided, and also the plates 24 shouldbe sufiiciently long so that, in spite of the high velocity, the arcs do not reach the end of the structure before the current zero.

In general, however, it may be preferable to work with the magnetic field and structure so proportioned that the arc does not pass beyond the slot up tothe time it is extinguished.

It will be evident that although in structure described the current in the arc-horns and arc in constitutes the principal ma net -m force exciting the blowout magnet, this arrangement is adJunctive rather than essential to my invention and that excitation of the blowoutmagnet with the arc or otherwise the scope of my invention. It will be evident that, if the groove, been characterised as V-shaped in my deionizlng structure isto have the effects described. it is advantageous, if not positively A shallruntoratheranarrowgroovelnorderthat thearcshall be in intimate-contact around a large part of its peripherywith the deionizing plates. 1

- In reference tox-the design of'my deionizing structure, it may held that reformation of the 9 3 effectively prevented in" which the are us through zero-will be most if the part of the groove located at currentzero is sometime to bring the arc'into this narrow slot i'rom point where it is drawn, it is necessary that the sides of the Vshall taper in gradually inthe manner showninl igasandd.

A study bf heat flow insuch plates as membars as has shown that only a relatively thin much part in carrying away heat where arcs are extinguishedin half a cycle of cycle current. Hence, the use ofheavy deionizing plates is uneconomical. 'The Y deionizing effect is greater the gr eaterthe num- 24 are not to be burned bythe which'has man, that it very narrow. At the ber of plates; wide spacing is, of course, poor economy; and much closer spacing than of an inch would be liable to cause trouble from dust accumulations or accidental introduction of other foreign matter between the plates. Thus the factors determining the design of rm; deionizing structure are evident.

By means of my invention, therefore, the arc incident to opening of into a deioni'zing structure where it is quenched before its has time to perceptibly burn or pit the plates thereof, this movement along the arc horns from its place of initial formation taking place so rapidly that no appreciable burnin of the contact-members occurs. In consequence, where the prior art has found oil switches necessary, air-break circuit breakers may be designedaccording to the principles of my invention for many conditions of service, with a re sulting decrease of cost and a greater ease, of installation and the elimination of fire hazard. Even on services where air-breaks have previ ously been used the circuit breakers may be made with lighter' parts and are of increased dur ability.

It will be understood that many features which I have described are adJunctiveto each other.

the contactor is driven.

purposes than those of circuit interruption. I,

therefore, desire that the language of the appended claims shall be accorded the broadest reasonable construction and that my invention be limited solely by what is explicitly stated in the claims and by the prior art.

I claim as my invention:

i. In combination, means to establish. an arc and a structure comprising a plurality of conducting plates having open spaces therebetween and alined notches oi V-shape, said notches halving in width in every longitudinal'distance o from. one tenth inch to two inches and positioned in a portion of the arc path.

2. In combination, means to establish an are means for moving saidarc into a deionizing structure,-means for extracting energy from said are as it is being moved into said'structure, said energy-extracting means comprising a groove, formed by aligned notches in aplurality of conducting plates having open spaces therebetweenfsaid notches' being'so ammonia increases as 5 increases, lbeing distance measured along the axis of the notch from its apex and w being width of the notch measured perpendicular to the axis. 1

3. In combination, means to establish an arc, means for moving said are into a deionlzing structure; means in intimate contact with said are for extracting energy therefrom a's it is being moved into said structure, said energy-exsaid notches curves convex.

w B r Ef crcee-eectionp! the arc and increase it: current density and potential.

an: which approaches lero width near its inner en l0. Incombinatiommeanetoeetabliehan arc. meanaiormovinzsaidarcintoadeicniaing means for extracting enemy from aaidarcasitiabeingmovedintosaidetructme, said enemy-extracting means comprising a movetormedbyalignednotcheeinaplurality of conducting plates having open spaces there.-

between, me notches being an mm um 1' increaaee'ulincreaeee,'lbein 'diatancem uredalongtheaxieotthenotchiromiteapex andicbeingwidth oi the notch measured perpendiculartotheaxia,and-said openepacea be-' tween the plates extending to two diiierent aides oithedeionizingetmctureeoaetoprovide through ventilating pae'eagee between theplates.

11. In an arc-extinguishing device, a plurality of metal plates having open spaces therebetween, each of said plates having a notch therein which tapers inwardly, which is large at its entrance and which approaches mm width near-it: inner end. and said "open spaces between the plates

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