US2068422A - Device for effectively quenching the arc - Google Patents

Description

Jan. 19, 1937. A. LOTZ DEVICE FOR EFFECTIVELY QUENCHING THE ARC Filed May 1935 Patented Jan. 19, 1937 UNITED- s'mi'rss- POATENT" OFFICE DEVICE FOR EFFECTIVELYQUENCHING THE ARC Application May 24, 1933, Serial No. 872,670

' In Germany May 24, 1932 13 Claims. (Cl. 200148) The invention relates to devices for effectively quenching the electric arcs which result from the separation of the contacts in switches or the melting of fusible cutouts and the like in alternating current circuits.

-There exist switches in which the arc is subjected to a powerful blast of compressed air or other gas during the time the current value is zero, and by this means a restoration of the arc with returning voltage is prevented. The blast of compressed air or other gas causes a lengthening of the arc and at the same time removes the ionized current carriers from the space between the electrodes.

In another type of switch two tubular e1ectrodes disposed within a pressure chamber are provided. When the electrodes separate the gas or liquid contained within the surrounding pressure chamber flows through the centrally disposed openings in the electrodes and thereby causes the arc to be-lengthened and the ends of the are to be moved within the hollow electrodes.

The present invention distinguishes from these previously known arrangements wherein a stream of air or other gas under very high pressure is used to lengthen the are both in structure and method of operation, The are is estab-, lished within a tubular passage formed in a suitable member of insulating material. The dimensions of the arc passage are such that the arc is closelvconflned by the adjacent walls, and the stream of arc extinguishing gas is admitted under moderate pressure, at right angles to the axis of the are passage. This stream of gas tends to press the are against the opposite wall of the arc passage. Movement of the arc in this direction is, however, definitelylimited, due to the presence of the confining walls of the arc passage, and in addition, ,it is impossible, because of the proportioning of the arc passage, for the out-flowing stream of gas to bow out the are as is done in the prior art structures. By this arrangement, any substantial lengthening of the arc is prevented, and in addition, the arc is held in a position where the outfiowing stream of gas can most effectively produce the desired extinc tion. In the accompanying drawing I have illus trated several embodiments of my preferred invention. I n

. Figure 1 shows the invention as applied to a fusible cutout. The fuse wire ,1" is clamped be-- tween electrodes a and b and extends through a tubular opening 02 formed within-an insulating body 0. When the wire ,f fuses, due to overload,

an arc is established in the opening or are pas- Q sage d. Perpendicular topassage d, is a channel e which passes through the insulating body 0, and through this channel, the momentan arc is formed, a gas such as air, carbon dioxide, or

the like is blown. The dimensions of the arc passage d within the insulating body c are such that the arc is forced against the opposite wall in the passage d and, by virtue of the confining action of that wall, is prevented from lengthening.

The resulting intimate co-mingling of the arc and the fresh un-ionized gas which is forced into the arc passage through the channel e effects the extinguishment of the arc at the first zero point in the current wave. The fresh un-ionized gas blown into the arc passagevents through either Figs. 2 and 3 show a switch according to my invention in the closed and opened positions,

respectively. The moving contact a is adapted fixed contact d. The cross sectional dimensions of the are passage d and the moving contact a are such that the conduit passage e utilized for introducing the arc extinguishing gas into the arc passage is substantially closed when the circuitis in the closed circuit position.

During the circuit opening operation the moving contact a is moved from the position shown in Fig. 2 to the position shown in Fig. 3. This movement draws an arc longitudinally ,within the arc passage d and at the same time allows a quantityof an arc extinguishing gas to be forced into the arc passage through the conduit opening e. The confining action of the arc passage it prevents the resulting stream of gas flowing therein from bowing out and thereby lengthening the arc, and sincethe passage is open at either end when the switch is in the open circuit position, the fresh un-ionized gas flowing through the arc passage effectively removes all of the current carrying bodies so as to prevent the restriking of the arc.

Figs. 4,8 and 6 show a switch wherein the cross sectional area of the arc passage maybe varied according to the physical dimensions of the are shown in Figs. 1 and 2. The are passage d wherein the moving contact it moves is defined by a pair or substantially parallel wall members 0 and is adapted to be closed at the lower end by a rectangular member I having a conduit opening e therein. The upper surface oi! the arc passage d is defined by a movable slider member h of insulating material which is biased toward the member 1 by means of a pair of suitable springs 1'.

When the switch is in the closed circuit position the slider member It bears against the upper surface of the rectangular moving contact a. As soon as the moving contact a disengages the arc passage d during the circuit opening operation, the slider it moves downwardly under the influence of its biasing springs so as to restrict the cross sectional area of the arc passage. The

amount or this restricting depends upon the physical dimensions or the arc, which is to say that it depends upon the magnitude oi the arc current, since one is a function of the other. By this arrangement a close confinement or the are within the arc passage dis assured, and the arc is prevented from bowing out and moving away from the in-coming stream of arc extinguishing gas which flows through the conduit e at right angles to the longitudinal axis of the arc passage. As a result, the arc is prevented from being lengthened by the in-flowing stream of gas. and a rapid extinguishment thereof is effected.

The length of the arc passage d, which is determined by the dimensions of the insulating body 0, depends upon the voltage and the characteristics of the circuit with which the switch is to be used. I! this voltage is very high, it is possible to arrange a plurality of devices such as that shown in Figs. 4, 5, and 6 in such manner that the arc passages d in the several units shall aline one with the other. II this is done, the interruption of the arc is greatly facilitated, due to the fact that individual sections thereoi are each subjected to a separate stream of gas which enters the arc passage 01. each of the several devices substantially at right angles to the longitudinal axis thereof. In other words each device acts to eflect the extingulshment of a section of the arc. It is, or course, necessary that the insulaing body c be so dimensioned that flash-over will not occur due to the presence of ionized gas or abnormal circuit voltage.

The are passage d within the insulating body c may be of any cross section, and the body c'may be 'formed of any suitable material, it being important merely that the material is insulating. Porcelain, molded material, fibre impregnated with artificial resin (hard paper, linen), alumina or steatite have all been used'with satisfactory results. 1: metal is used in any portion of the wall defining body 0', it is necessary that the surface thereof which is exposed to the arc shall be provided with a layer oi insulating material capable of withstanding the normal circuit voltage. It is possible to use wood (particularlyoak or beech) or oil impregnated wood for defining thewallsotthearce.

In the two structures illustrated there is only one conduit or channel e through which the arc extinguishing gas is introduced into the 'arc passage. It may be desirable to provide an annular space disposed around the arc passage d which is provided with a number of radially directed borings connected with" the arc passage. If this is done, the arc extinguishing gas may be caused to flow into the arc passage at a plurality of similar to the contacts a and b of. the switch points and the operation will thereby be somewhat improved.

For cooling purposes, the arc passage wherein the arc is formed may be surrounded by a water jacket, the simplest means of accomplishing this being the provision or an annular passage within the walls oi! an insulating body, and ii desired, small channels may be provided leading from this space into the arc passage itself in such manner that the cooling water may percolate down through these channels so as to cover the internal, surface of the arc passage with a film of water.

Fig. Tillustrates schematically one method of connecting a circuit interrupter according to my invention into an electrical circuit. As shown, the moving contact a of the breaker which is electrically connected to one side or the power circuit, is adapted to move within a suitable guide means a, and is biased to the open circuit position by a spring h associated with the breaker operating solenoid k. A gas reservoir is provided for producing the blast of arc extinguishing gas through the arc passage :1 within the insulating body 0, and the liberation of this gas is controlled by an electromagnetic valve. An overload relay electrically connected in the power circuit is provided for controlling the operation of the switch and the electromagnetic valve. The breaker operating solenoid k is normally energized in order to hold the contacts in the closed circuit position.

Upon the occurrence of an overload, the over load relay moves to deenergize the electromagnetic valve and the breaker operating solenoid I: thereby making it possible for the biasing spring h to move the contacts to the open circuit position.

At the same time the electromagnetic valve operated tocause a definite quantity or the gas contained within the gasreservoir to flow through the arc passage, thereby eii'ecting the extinguishment of the are which is drawn therein.

It will thus be seen that I have provided an improved circuit interrupter wherein the are which is established incident to the opening of the connected circuit is extinguished through the agency 01' a flowing stream of un-ionized gas. The structure of my invention difiers from the devices already known to the art in that the arc is so confined that the stream of arc extinguishing gas does not effect a substantial lengthening of the arc, but intimately co-mingles with the arc and thereby operates much more eiiiciently in effecting the extinguishment thereof.

I claim as my invention:

1. In a circuit interrupter, means at least partially of insulating material for defining the walls or an arc passage having a length which is at least several times its greatest cross sectional dimension, means for establishing an are within said are passage, and means including a conduit which opens into said arc passage intermediate itsends for causing a quantity of arc extinguishing fluid to flow through said arc passage during each circuit interrupting operation in order to eflfect the extinguishment of said arc, said are passage being open at least at one end when said interrupter is in the open circuit position, and at least a portion oi said wall defining means comprising a member of insulating material which is movable to vary the cross sectional area of said are passage during the circuit opening operation so as to prevent said quantity of fluid from bowing said arc.

2. In a circuit interrupter, means at least partially of insulating material for defining the walls of an arc passage having a length which is at least several times its greatest cross sectional dimension, means for establishing an arc within said are passage, and means including a conduit which opens into said arc passage intermediate its ends for causing a quantity of arc extinguishing fluid to flow through said are passage during each circuit interrupting operation in order to effect the extinguishment of said are, said are passage being open at both ends when said interrupter is in the open circuit position and, except for said conduit, being otherwise closed, said fluid being introduced into said passage under pressure and ata substantial angle to the longitudinal axis thereof, and at least a portion of said wall defining means comprising a member of insulating material which is movable to vary the cross sectional area of said are passage in response to the physical dimensions of the are which is established therein during the circuit opening operation, thereby preventing said quantity of fluid from bowing or otherwise lengthening said are. 3. In a circuit interrupter, means at least partially of insulating material for defining the walls of an arc passage having a length which is at least several times its greatest cross sectional dimension, means for establishing an are within said arc passage, means including a conduit which opens into said are passage intermediate its ends for causing a quantity of arc extinguishing fluid to flow through said are passage during each circuit interrupting operation in order to eflect the extinguishment of said are, said are passage being open at least at one end when said interrupter is in the open circuit position, and means for varying the cross sectional area of saidare passage in response to the physical dimensions of the are which is established therein during thev circuit opening operation, thereby preventing said quantity of fluid from bowing or otherwise lengthening said arc, said area varying means compris-v ing a member movable into said are passage during the operation of said interrupter and means for moving said member in such manner that the cross sectional area of said are passage shall be proportional to the physical dimension of the arc which is established therein.

4. In a circuit interrupter, a pair oi oppositely disposed, spaced plates formed at least partially of insulating material and each of which has a considerable surface area, for defining two of the walls of an arc passage, means for establishing the arc incident to each opening operation of said interrupter within said are passage, and means for defining the other walls of said are passage, including a member slidable edgewise in the plane of said arc between said pair of opposed plate members to cause the dimensions of said are passage to be varied in response to the current magnitude of the are which is established therein during the operation of the said interrupter. I v

5. In a circuit interrupter, a pair of substantially flat plates of insulating material, positioned in parallel planes and spaced some distance from each other, for defining two of the opposed walls of a rectangular arc passage, means of insulating material for defining the other two walls oi. said arc passage in order that said passage shall be sage including a flat member of insulating material slidable edgewise in the plane of said are between said opposed plate members to vary the dimensions of said are passage in accordance with the current magnitude of the are which is established therein, and means for resiliently biasing said slidable member to a position where the cross sectional area of said are passageis reduced to a predetermined minimum.

6. In a circuit interrupter, a pair of substantially flat plates of insulating material, disposed,

in parallel planes and spaced some distance from each other, for defining two of the opposed walls lishing the arc incident to each opening operation of said interrupter within said are passage, said means for'defining the other two walls of said are passage including a member of insulating material slidable. between said opposed plates to vary the dimensions of said arc passage in accordance with the current magnitude of .the are which is established therein, and means, including a con-' duit which opens into said arc passage intermediate the ends thereof, for causing a. quantity of arc extinguishing fluid to flow through said arc passage during each circuit interrupting operation, said slidable member causing the physical dimensions of said are passage to closely approximate the physical dimensions of said are at all times, thereby effecting intimate contact between said are extinguishing fluid and the arc.

7. In a circuit interrupter, means, at least partially of insulating material, for defining the walls of an arc passage having a length which is at least several times its greatest cross section dimension, means for establishing the arc incident to each opening operation of said interrupter within said are passage, means including a conduit which opens into said are passage intermediate its ends, for causing a quantity of arc extinguishing fluid to flow through said are passage during each circuit opening operation in order to effect the extinguishment of said arc, and means for varying the cross sectional area of said are passage in response to the physical dimensions of the arc which is established therein during the operation of said interrupter, in order to assure intimate contact between said are extinguishing fluid and said arc.

8. In a circuit interrupter, means, at least partially of insulating material, for defining the walls of an arc passage having a length which is at least several times its greatest cross sectional dimension, means for establishing the arc incident to the opening of said interrupter longitudinally within said are passage, and'iiieans, including a conduit which opens into said are passage intermediate its ends-for causing a quantity of arc extinguishing fluid to flow through said are passage during each circuit interrupting operation in order to efi'ect the extinguishment of said arc, said are passage being open at least at one end when said interrupter is in the open circuit position and except for said conduit being otherwise substantially completely enclosed, said well defining means including a member of insulating material which is movable'to vary the cross sectional area of said are passage in response to the physical dimensions of the are which is established therein during the operation of said interrupter, thereby assuring intimate contact between said are extinguishing fluid and said are.

9. In a circuit interrupter, means at least partially of insulating material for defining the walls of an arc passage having a length which is at least several times its greatest cross sectional dimension, means for establishing the arc incident to the opening of said interrupter longitudinally within said are passage, means, including a con duit which opens into said are passage. intermediate its ends, for causing a quantity of arc extinguishing fluid to flow through said are passage during each circuit interrupting operation, in' order to effect the extinguishment of said are, said are passage being open at both ends when said interrupter is in the open circuit position and except for said conduit means being otherwise substantially completely enclosed, said fluid being introduced into said passage under pressure, and at least a portion of said wall defining means comprising a resiliently biased member of insulating material which is movable to vary the cross sectional area of said are passage in response to the physical dimensions of the are which is established therein during the operation of said interrupter.

10. In a circuit interrupter, means at least partially of insulating material for defining the walls of an arc passage, means for establishing the .arc incident to each opening operation of said intcrrupter within said are passage, a source of arc extinguishing fluid external to the arc passage, means for causing a blast of said are extinguishing fluid to be moved into and to flow through said are passage longitudinally thereof to effect the cxtinguishment of said arc,'said arc passage being open at least at one end thereof during each arc extinguishing operation and being otherwise substantially completely enclosed, and movable means of insulating material for varying the cross sectional area of said are passage intermediate said are establishing means in response to the physical dimensions of the arc which is established therein during the operation of said interrupter in order to assure intimate contact between said are extinguishing fluid and said arc.

11. In a circuit interrupter, means at least partially of insulating material for defining the walls of an arc passage having a length which is at least several times its greatest cross sectional dimension, means for establishing the arc incident to each opening operation of said interrupter within said are passage, a body of arc extinguishing fluid, means including a conduit which opens into said are passage intermediate its ends for causing a quantity of said are extinguishing fluid to be moved into and to flow through said are passage during each circuit opening operation to elect the extinguishrnent of said are, said'arc passage being open at least at one of its ends during each arc extinguishing operation and except for said conduit being otherwise substantially com- 2,oes,422

pletely enclosed, said are extinguishing fluid being introduced into said are passage under pressure and at a substantial angle to the longitudinal axis thereof, and meansfor varying the cross sectional area of said are passage in response to the physical dimensions of the are which is established therein during the operation of said interrupter in order to assure intimatecontact between said are extinguishing fluid and said are.

12. In a circuit interrupter, means at least partially of insulating material for defining the walls of an arc passage having a length which is at least several times its greatest cross sectional dimensions, means for establishing the arc incident to each opening operation of said interrupter longitudinally within said are passage, a body of arc extinguishing fluid, and means including a conduit which opens into said are passage intermediate its ends for causing a quantity of said are extinguishing fluid to flow through said arc passage duringeach circuit interrupting operation in order to effect the extinguishment of said arc,

said are passage being open at least at one end during each arc extinguishing operation and ex cept for said conduit means being otherwise sub stantially completely enclosed, said fluid being introduced into said are passage under pressure and at a substantial angle to the longitudinal axis thereof, and at least a portion of said wall delining means comprising a resilient biased member of insulating material which is movable to vary the cross sectional area of said are passage in response to the physical dimensions of the are which is established therein during the operation of said interrupter.

13. In a circuit interrupter, a pair of substantially flat plates of insulating material disposed in parallel planes and spaced some distance from each other for defining two of the opposed walls of an arc passage having the general form of a rectangular prism, means for establishing the arc incident to each opening operation of said interrupter within said are passage, means for defining the other two walls of said arc passage including a member of insulating material slidable between said opposed plates to vary the dimensions of said arc passage in accordance with the physical dimensions of the are which is established therein, and means for causing a blast of arc extinguishing fluid to flow through said are passage during each circuit interrupting operation

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