US2130999A - Electric circuit interrupter - Google Patents

Description

RMICHL 2,130,999

Sept. 20, 1938.

Sept. 20, 1938. F. PET-ERMICHL ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 15, 1937 3 Sheets-Sheet2 Inventor FT'amz peter'rnichl,

His Attorney.

Sept. 20, 1938; F. PETERMICHL 2,130,999

Filed Feb. 15, 1937 I s Sheets-Sheet s nsulation Ifivenbov. Franz Pebew mic'hl, w x/ 54W 745 Abtovneg.

Patented Sept. 20, 1938 UNITED STATES PATENT OFFICE.

ELECTRIC CIRCUIT INTERBUPTER a ucauon February 15, 1937, Serial No. 125,919

- In Germany February 28, 1936 6 Claims. (Cl. 200-149) My invention relates to electric circuit interrupters of the expulsion type wherein an arc-extinguishing gas is generated upon opening of the circuit by the action of thearc on a material closely confining or in direct contact with the arc. The gas so generated is suitably directed so as. to cause interruption of the arc.

More particularly, the invention is concerned with an electrical switch wherein the arc is D quenched by means of pressure gas. The gas is liberated by the arc to be interrupted in a switch tube, which consists of rigid materials adapted to emit gas under the influence of heat, or is lined with such materials. More specifically, in a preferred form of my invention the contact point of the movable switch member, from which the arc extends to the fixed or counter-contact after contact separation, is moved directly through an arc quenching passage or channel wherein the arc quenching gas is produced by the contact of the arc with the inner gas-yielding walls of the passage.

In each case the quantity of liberated arc quenching gas depends on the intensity oi the ourrent to be interrupted, on the size of the surface of the switch tube in contact with the are and on the duration of the arc. Consequently, in order to produce the quantity of gas required for the quenching of small currents, it is necessary to J use a longer switch tube than for the quenching process of large currents. However, a long switch tube, dimensioned for the quenching of small currents, works out unfavorably when switching of]! large currents. That is, since the quenching of 5 thearc is generally efiected directly when the contact point of the movable switch member uncovers the blow-out end of the quenching tube and thereby releases a quenching blast, the burning duration of the arc is unnecessarily prolonged when switching ofilarge currents. During this entire additional period, however, the insulating material linings and the switch contacts are subjected to great stress by the powerful arcs, without aiding the actual quenching process. 5 The result is a greater wear and deterioration of the gas-yielding material and of the contact material, and also excessive and unnecessary stress uponthe arc chambers by the pressure of the heated gases produced by the arc.

) A'principal object of the present invention is the provision of an improved circuit interrupter of the aforesaid type which is eflicient, reliable and positive in operation throughout the entire range of, its interrupting capacity.

; According to my invention, the aforesaid drawback is obviated in a simple manner by dividing up the quenching channel which isformed by gasyielding materials and through which the contact point of the movable contact is drawn when opening the circuit, in such a way that adjoining the 5 fixed switch contact there is an arc quenching channel structure whose length is dimensioned for the interruption of large currents. The channel then comprises an intermediate expansion or blow-out chamber wherein the large currents are 10 interrupted. A further quenching channel is in communication with the expansion chamber and its length is so dimensioned that it produces together with the first quenching channel structure the requisite length of switch tube for certain quenching of the arcs of small currents. The intermediate expansion or-blow-out chamber can be closed except for the passage openings for the movable switch member. It can, however, also be vented to the surrounding air by means of an exhaust passage extending to the blow-out end of the switch tube, or by means of openings provided in the switch casing. Under certain circumstances as hereinafter described it may be expedient to arrange valves in those openings.

My invention will be more fully set forth in the following description referring to the accompanying drawings, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawings, Fig. 1 is an elevational, sectional view of an electric circuit breaker embodying the present invention, and Figs. 2 and 3 are similar views of other forms my invention may 36 assume.

The switch as shown in Fig. 1 is constructed in accordance with the invention and consists essentially of two tubular pieces I and 2 of gasyielding insulating material, whichare spaced 40 within a supporting sleeve or casing 3. The chamber so formed between the same comprises an expansion or blow-out chamber 4. Inthe constructional example, an exhaust channel 5 vents the intermediate channel or expansion chamber 4 to the blow-out end of the switch tube, at the opposite closed end of which the fixed contact 6 is arranged. 'This contact coacts with the tubeshaped movable switch member 1, into which a bolt 8 of insulating material projects from the base of sleeve 3. The members I, 2 and 8 are composed of a suitable gas-yielding material such as fibre and closely confine the arc during the interrupting process.

When switching of! large currents, considerau .2 arouses ble quantities or" gas are liberated from the insulating tubular structure I! by the are. Directly the contact point or tip of the movable contact 7 leaves the structure l a quenching stream of gas is released and directed as indicated in the direction of the expansion chamber l, owing to the pressure difference between the compartment encornpassing the fixed contact and the expansion. chamber l. As a result of this gas blast the arc is quenched, without i e-ignit o the arc during the further course of the switching-off stroke of the movable switch member, by reason. of the fact that the gases still remaining under pressure in the tube i and in the intermediate chamber l insulate the contact the recovery voltage. Heavy current arcs are therefore interrupted before the contact '1 enters the tube On the other hand, when interrupting small currents, the quantity of quenching gas liberated the are from the first ins ng tube is so slight that it does not suirlce the quenching of the arc and insulation respect to the recovery voltage. Instead the are is drawn through the intermediate chamber d and continues within the tube 2. Accordin ly the development of gas increases to such an extent that the main quenching blast set up upon emergence of the movable contact 'i from the exhaust opening of the switch tube causes the arc to be quenched.

in the arrangement according to my invention arcs of great current inten therefore quenched more quickly than 'herto. Consequently the wear'and deterior .uori of the switch parts under the influence or" the arc and the stress upon the parts exposed the pressure of the switch gases are less than they were hitherto. fhis limiting or the arc duration in the case of large currents is of especial importance in con nection with the contact wear tor the reason. that the metal parts which are greatly heatedup in the first'half-cycle of the are thereafter subject to greater deterioration. wear in= creases in a far greater progression than corresponds with the are duration.

A further advantage of the arrangement according to my invention is that the hot gases produced when switching off large currents are not conducted directly through the tube 2 which is utilized for the quenching or the small currents. The gases are instead cooled in the inter mediate compartment l through expansion, so that only the tube l is essentially subjected to wear due to heavy current arcs. Consequently when switching off large currents, the chamber will remain better suited to the interruption of small currents than would a chamber without an arrangement according to the invention, which is subjected to wear along its entire length when switching off large currents.

In certain circumstances it may be expedient to make the tube structure i of more than one piece of gas-yielding material such as of individual plates provided with bores and stacked in,

spaced layers. The expansion chamber is formed by the spaces between the plates. Fig. 2 illustrates such an arrangement. I

'As in the previous case the object consists in guaranteeing safe extinguishing of the are not only at highand low current values but also at critical medium current intensities. This object is attained in'the present case by so constructing the switch tube adjacent the fixed switch contact of gas-yielding material that the arc is subjected to a transversal blowing and lengthening thereof tact at the base of the arc.

within the spaces forming the expansion chamber. During this operation the movable switch member keeps the exhaust end of the extinguishing tube closed.

It is especially advantageous to make the end of the extinguishing tube at the fixed switch con-- tact, of single plates, which are arranged in layers with the interpos tion of spacers Apertures are provided in these plates, '1 open into a suitably positioned discharge duct.

mode of execution according to this aspect of the invention, in the application to gas expulsion switches wherein the switch tubes consist of a cylindrical part with concentrically inserted bolts of insulating material, and the movable switch member consists of a'tube contact, as n. the case of Fig. has the following material advantage. It has been observed that in tube contacts, the base of the are at the lower contact edge heats up the metal. of the contact to its fusion point, and that the extinguishing gas di rested in the direction of the circuit opening movement blows the fused particles of the contact into the narrow gap between the tube con tact and the walls of the switch chamber. Thereby the surface of the tube contact is given a rough coating which upon hardening has a destructive effect on the walls of the extinguish ing tube particularly when switching on again. At the same time, however, a breach or depression originates naturally in the edge of the tube com "Upon the next switching operation the base of the arc is driven upwards to the edge of the tube contact under the influence of the extinguishing gas current, until it comes to rest at the breach, and the process described above is repeated with the .result that the becomes deeper and deeper, and a very uneven biu'nir g of the tube contact takes place, whi h therefore be repaired prematurely.

ihis d sadva tage overcome by the present form of the invention, since the direction of the gas blast, as long as the tube contact l ns the exhaust end of the tube closed, will be essentially opposed to the direction of movement of the tube contact.

Finally, according to this aspect of the lnvention, the apertures in the plates forming one end of the extinguishing passage can be displaced opposite each other, as for example along a spiral path. By this means the points of the are which are subjected to the strongest transversal blast, i. e. in the air pockets or expansion spaces between the single plates of the insulating gasyielding material, are displaced spirally in the same manner. "in this way rotation of the arc, promoting the extinguishing of the arc, is attained.

Referring more particularly to Fig. 2, 2i indie cates the switch chamber, which surrounds the fixed tulip-shaped contact 22 and cooperates with the movable tube shaped switch contact 23. The switch chamber is formed by a generally tubular structure made of insulating material capable under influence of the arc of giving oil? gas. The tubular structure comprises an integral tube 24 at the exhaust end, and single discs 25 in the region of the fixed contact 22. The discs 25, which have centrally alined apertures for the contact 23, are spaced by members 26, and together with the fixed tube 24, form a continuous passage for the passage of the movable switch tube 23. Within the passage 2. bolt 21 of insulating material, appropriately of material adapted to give ofl gas, is arranged concentrically. The bolt 21, positioned centrally of the contact tube 23, is fixed to the cover 23, which in the form shown by way of example, surrounds the fixed contact 22 and also the end of the extinguishing tube formed by the discs 25.

Apcrtures 25 are provided in the discs 25 and are arranged in superimposed position, as shown, or displaced with respect to each other. The

) extinguishing gases exhausting through the intermediate spaces forming the expansion chamber between the plates and through the apertures 25, can escape freely through passages 24' in the tube 24.

5 Under certain circumstances for attaining as powerful a transverse blast between the discs as possible, a packing 23' can to advantage be located in the fixed tube 24 for preventing initial exhaust of the extinguishing gases along the tube 6 contact 23, as long as the contact is within the extinguishing tubes. A simple assembly of the switch chamber is also possible by providing in the interior or the-recessed cover 28, projections 28' for retaining the plates 25 and their spacing ;5 rings 26. The plates and rings are held'in this position by screwing the fixed insulating tube 24 into the cover 23 as shown.

The manner of operation of the gas expulsion switch according to the present form of my invention, is as follows:

The arc l3, which is drawn between the contacts 22 and 23 upon switching off immediately develops extinguishing gas from the gas-yielding walls at 25. This gas is under pressure as compared with the surrounding air. The result is that the arc is driven into the intermediate expansion space between the plates 25 and undergoes considerable lengthening, so that its resistance is weakened. Since at this time the path 40 through the exhaust end of the extinguishing tube is entirely or for the most part blocked against the extinguishing gases, they necessarily flow through the intermediate spaces between the plates, through the apertures provided therein,

45 to the discharge passage in the fixed extinguishing tube 24. A, powerful transverse blast is therefore directed through the are at several places at the same time.

The combined action of both these phenomena, 50 practically insures together with the later main extinguishing blast at the exhaust of the extinguishing tube, a safe extinguishing of the arc for both small and medium currents as well as with large current. As in the case of Fig. 1 small tube 24.

The dimensions of 'the apertures 25' and of the passages 23' must of course be chosen in such a manner, that upon the extinguishing of large currents, notwithstanding the direct connection with atmosphere, an adequate extinguishing pressure can build up in the switch tube.

Fig. 3 illustrates an arrangement fundamentally similar to Fig. l and comprises an improvement in a gas expulsion switch of this kind. It has become evident, that the cubic contents of the intermediate or expansion chamber must be sufficiently great for the generation of an adequate blast forthe quick quenching of large 0 current arcs and that, on the other hand, when the intermediate chamber is restricted in volume, smaller currents, even at higher voltages, can be better interrupted. These requirements, opposed to each other, can be met by providing valves 5 which regulate the inlet of the quenching gases currents are readily interrupted within the into the intermediate expansion chamber, in accordance with the strength of the current to be switched ofl.

These difllculties are obviated, in accordance with the present form of my .invention by separating the intermediate chamber, preferably in direct communication with the outer air, from the gas-forming chamber proper, by an automatically operating valve, such as an annular slide valve, for bridging the space between the two gas-yielding tube-pieces.

In accordance with the interrupting conditions, the annular slide-valve opens more or'less in response to one component of the compressed gas in opposition to the force of a spring.

With a development of this kind, the small currents .also, are reliably quenched by the gas flow, as the movable switch rod passes out of the first part of the quenching tube. Surprisingly, a phenomenon, favorable to the voltage arcquenching, is that the arc voltage is slight, both when switching-out small as well as great currents. Besides this a further advantage is that the annular slide also can if desired be made of gas-yielding material, although advantageously of a somewhat less readily vaporizing material, and can thus be utilized for developing quenching gas.

Referring more particularly to Fig. 3, the unching chamber of the gas-switch is formed by the two pieces of tube 3| and 32 which are composed of a material adapted to give of! gas under the influence of the arc, and which are spaced in a supporting body 33. At one end of the tube 3| is provided the fixed contact 34, which cooperates, in the embodiment shown by way of an example, with the movable 'tubular switchcontact 35. A bolt 36 of insulating material, preferably of gas-yielding material, extends into the contact 35 from the closed end of the supporting body 33. The chamber 31, disposed between the tubes 3| and 32, is in communication with the outside air, directly or indirectly,

through apertures 38.

In accordance with my invention, an annular slide valve 39 is mounted on the tube-member 32 and is under the influence of a spring 3|]. The valve is provided with a pressure-surface 39' which is acted upon by the switch-gases, and is of suitable form, as a conical turned-down part, for instance. In its closed or normal position, it seats on the casing 33 carrying the tube-member 3|. The annular slide 33 may also consist of gas-yielding material and may, of course, if desired be guided on the other tube-member 3| or in the walls of the casing 33.

The operation of this form of the gas-switch, in accordance with my invention is as follows:

On switching off a current of any magnitude, a quantity of quenching-gas is first freed from the tube-member der pressure move the slide 39 more or less away from the casing 33 and a blast takes place through the annular gap so formed, into the intermediate or expansion chamber formed by the casing 33. This blast quenches the arcs of great and also of comparatively small or medium currents.

With quite small currents, on theother hand, the slide 33 remains closed so that the arc passage is restricted and the gas formation, requisite for the switching-off of these currents, proceeds unhindered until the contact point of the movable switch member leaves the quenching The gases so developed untube. At this point, the exhaust lolast effectively interrupts a lingering are.

lit should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art Without departing from the spirit of my invention.

i /hat I claim as new and desire to secure by Letters Patent of .c States 1. An electric circuit interrupter the gas expulsion type comprising relatively movable con-- formed at said contacts being initially drawn through said expansion chamber and subsequently iii the case of a persisting are through said restricted passage, said insulating structure adjacent to the point of initial formation of said are in said expansion chamber and in said restricted passage being composed of a material adapted to emit an arc-extinguislung gas When subjected to said arc.

2. An electric interrupter of the gas expulsion type comprising a fixed contact, a coacting movable contact, and a casing including insulating structure for mounting at one end thereof said fixed contact, said being closed at said end, said structure arranged to form a confining substantially enclosed passage tor the are between said contacts upon opening of the circuit, said passage being enlarged adjacent said fixed contact to form an expansion chamber arranged to have a direct exhaust to atmosphere, being restricted with respect to sa d movable co: ct at a point remote from said 1 seal contact, said insulating structure immediately adjacent to said fixed contact being composed of material adapted to emit an arc-extinguishing gas when subjected to said arc.

3. An electric circuit interrupter of the gas expulsion type comprising relatively movable contacts, and casin including insulating structure arranged to form a confining passage for the are drawn between said contacts upon opening of the circuit, said casing adjacent one of said contacts enclosing a plurality of spaced plates having substantially alined apertures through which said are is drawn, a cylindrical member having a s1eeve-1ilre bore restricted with respect to the other of said contacts through which said arc arouses can subsequently be drawn, said plates and cylinder being composed oi a material adapted to emit an arc-extinguishing gas when subjected to said arc,.spaces between said plates being vented to atmosphere independently of restricted bore so that the gas pressure generated upon initial. formation of said arctends to force said are laterally between said. plates.

An electric circuit interrupter, of the gas expulsion type comprising relatively movable contacts, and insulating stru Sure arranged to form confining passage for 1e arc drawn between said contacts upon opening of the circuit, said insulating structure adjacent one of said contacts closely confining in. sleeve-like relation the arc the initial formation thereof and at a point remote from said contact consisting of a cylindrical member likewise closely confining said arc, said confining passage including an expansion chamber vented to atmosphere interposed between said cylindrical passages, said insulating structure at said passages being composed of a material adapted to emit an arc-extirwuishing gas When subjected to said are. 5. An electric circuit interrupter of the expulsion type comprising relatively movable contacts, insulating structure arranged to form a confining passage for the are drawn between said contacts upon opening of the circuit, said insulating structure adjacent one of said contacts consisting of spaced plates having substantially aliuecl apertures through which said are is dravm, said plates also having apertures interconnecting the spaces between said plates, said insulating structure also comprising at a poin remote from said contact a cylindrical member having bore restricted with respect to the other? contacts through which said are car; subsequently be drawn, said plates and cylinder being c nosed of material adapted to an arc-extinguishing when subjected to said 5. An electric circuit interrupter of the expulsion type comprising relatively movable contacts, and insulating structure for confining the are formed at said contacts upon opening of the circuit, said insulating structure defining an expansion chamber adjacent the point of initial separation of said contacts and also including a cylindrical member for defining restricted passage in communication with said expansion chamber through which the are can subsequently be drawn, one of said contacts being movable through said-restricted passage, said expansion chamber being vented to exhaust at a point ad jacent the exhaust of said restricted passage independently of said restricted passage, said insulating structure including in part a material adapted to emit an arc-eirtiziguishiug gas when subjected to said are.

FRANZ PETERBMCHL.

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