US3538283A - Method and device for the deionization of the electric arc zone between the contacts of an oilbreak-switch - Google Patents

Description

1970 N. GHEORGHIU 3,538,283

METHOD AND DEVICE FOR THE DEIONIZATION OF THE ELECTRIC ARC ZONE BETWEEN THE CONTACTS OF AN OILBREAK'SWITCH Filed May 5, 1968 4 Sheets-Sheet 1 Fig.

7 Nicolaie cmzoacuw lnven/ar:

Attorne 1970 N. GHEORGHIU 3,538,283

OR THE DEIONIZATION OF THE ELECTRIC REAK-SWITCH METHOD AND DEVICE F ARC ZONE BETWEEN THE CONTACTS OF AN OILB 4 Sheets-Sheet 2 Filed May 3, 1968 Fig. 2 I

Nicolaie GHEORGHIU lave/liar:

flll'iornev 3, 1970 N. GHEORGHIU 3,538,283

METHOD AND DEVICE FOR THE DEIONIZATION OF THE ELECTRIC ARC ZONE BETWEEN THE CONTACTS-OF'AN OILBREAK-SWITCH Filed May 5, 1968 4 Sheets-Sheet 5 Nicolaie GHEORGHIU /n van for Aifomey Nbv. 3, 1970 N. GHEORGHIU I 3,538,283"

METHOD AND DEVICE FOR THE DEIONIZATION OF THE ELECTRIC ARC ZONE BETWEEN THE CONTACTS OF AN OILBREAK-SWITCH Filed May 5, 1968 1 v 4 Sheets-Sheet 4 Nicqlaie GHEORGH IU lave/liar:

ma l g Attorney United States Patent 3,538,283 METHOD AND DEVICE FOR THE DEIONIZATION OF THE ELECTRIC ARC ZONE BETWEEN THE CONTACTS OF AN OILBREAK-SWITCH Nicolaie Gheorghiu, Bucharest, Rumauia, assignor t0 Intreprinderea Pentru Rationalizarea si Modernizarea Instalatiilor Energetice, Bucharest, Rumania Filed May 3, 1968, Ser. No. 726,361 Claims priority, application Rumania, July 14, 1967, 54,251, Dec. 20, 1967, 55,381 Int. Cl. H01h 33/68 U.S. Cl. 200-150 5 Claims ABSTRACT OF THE DISCLOSURE A system for quenching the circuit-breaking arc of an oil-filled switch in which a plurality of oil-entraining members are successively swept through the arc zone in step with the movement of the displaceable contact to subdivide the arc, entrain fresh quantities of oil into the zone and sweep ionized products and ionization or decomposition products from the gap.

My present invention relates to a method of and a system for the quenching of the circuit-breaking are developing upon the separation of the contacts of an oilbreak switch.

While various methods have been proposed for the extinction and quenching of the circuit-breaking arc of an oil-break switch, such systems have generally required one or more of the following expedients:

(a) Rapid replacement of the dielelectric fluid in the arc zone between the fixed or stationary contact and the movable contact to eliminate conductive particles (e.g. ionization and decomposition products and ionized particles) from the zone between the contracts at least in part as a result of the rapid replacement of the dielectric fluid and the mechanical entrainment of these products therewith. This system also etfectively increases the insulating capacity of the dielectric in the zone after incipient arc formation;

(b) Reducing the degree of ionization in the intercontact gap or zone by cooling this zone and rapidly conducting the ionized gases therefromv through blowout chamber or the like; and

(c) Subdividing the arc bridging the contacts with the aid of numerous auxiliary contacts and thereby dissipating the are energy in a rapid and effective manner.

Each of these techniques or their use in combination enables quenching the contact-opening are provided that the ionization in the region of the gap is substantially completely eliminated or the dielectric character of the gap is restored by the time the electric-current Wave (which is generally sinusoidal) passes through its zeroamplitude level. If the dissipation is insulficiently rapid, the succeeding increase in amplitude of the alternatingcurrent wave form will cause an are again to jump between the contacts. In commercial realizations of these systems, automatically operable blowout devices have been proposed for sweeping the arc zone clear of conductive substances with oil or gas or the use of a magnetic field, self-induced, to retard the formation of or in- 3,538,283 Patented Nov. 3, 1970 crease the speed of extinction of the electric are. In none of these prior-art systems, however, has it been possible to achieve an optimum blowout rate under all circumstances. In part, it is believed that these difficulties arise from the use of piston-type pumps and the like for quenching fluid through the zone.

It is, therefore, the principal object of the present invention to provide an improved method of and a system for the high-speed de-ionization of the arc zone of an Oil-immersed circuit-breaker contact arrangement.

Another object of this invention is to provide a method of quenching the are generated upon separation of a movable contact of an alternating current switch which operates with assurance of etfective arc quenching, is of simple construction, and has the advantages of an oilinjection arc blower.

I have now found that it is possible to obtain the advantages of the piston-type oil-injection blowout arrangement, without the disadvantages thereof, by simultaneously entraining fresh quantities of oil into the arc zone between a pair of relatively movable contacts and sectioning or breaking up the arc bridging the contacts by displacing through the zone at high rates a succession of oil-entraining nonconductive members in step with the separation of the movable contact from the fixed or stationary contact of the switch. To this end, an array of equispaced members is provided, the members being angularly or linearly displaceable to constitute both an impeller (serving to displace the dielectric liquid or oil from surrounding regions of the Oil bath into the spark zone) and an arc interrupter which mechanically breaks up any are bridging the contacts. The arc-fragmenting members constitute a pump disposed directly in the zone and thus are substantially more efiective in entraining cool fresh oil into the zone and carrying ionized products and ionization products out of this zone than are priorart pumping systems. Furthermore, the members alternately interpose themselves between the contacts and thereby decrease the duration of any are actually bridging the contacts. By sectioning the current and thereby effectively creating an insulating shield between the contacts at the time the current wave form passes through a zero-amplitude level, it is possible to limit overvoltages to which are attributed many of the disadvantages of the earlier systems.

More specifically, the device of the present invention may comprise a support carrying or disposed adjacent the fixed contact and defining a guide path for an angular or linear array of members, constituted of blade-like configuration or with fins extending transversely to the plane or their displacement, this plane extending perpendicularly to the direction of displacement of the carriage upon which the movable contact is mounted. A motion-transferring means, e.g. in the form of a cam on the carriage,

'co-operates with the array of members to sweep the array may have an inwardly directed radial pin received in the helical groove.

When the array is linearly displaceable and of a conelike configuration, I prefer to bias the array via a spring or the like against a wedge-shaped cam extending from the movable contact carriage into sliding contact with the array.

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a perspective view, partly in diagrammatic form and partly broken away, of the co-operating parts of an arc-quenching system for the oil-immersed contacts of a three-phase alternating-current switch, the oil filling the region illustrated in the drawing;

FIG. 2 is a plan view of the switch;

FIG. 3 is a plan view of the array of arc-sectioning and oil-transporting blades of the present invention;

FIG. 4 is an elevational view of the motion-translating means therefore; and

FIG. 5 is a perspective view similar to that of FIG. 1 but illustrating another embodiment of this invention.

In FIGS. 1-4 of the drawing, I show a three-phase switch, one of the contacts of which has been illustrated in FIG. 1. In the housing 1 (FIG. 2), insulating sleeves 3 support contact pairs 2, each of which is connected to one phase of the line current and to a respective load terminal via suitable terminals not shown. The contacts 2 are bridge by a conductive carriage 5 supporting respective movable contacts 6 afiixed to the carriage. The housing 1 also carries a support 4 consisting of a block 4a which carries the pair of guide plates 12 and 13 between which an array of blade-like arms 8 are guided. These angularly equispaced arms are carried by a hub 7 and together form a sector of the hub, each of the arms being sector-shaped in turn.

The carriage 5 is vertically displaceable (FIG. 1) to bring-the contacts 6 into and out of engagement with the contacts 2 aligned therewith, this movement being represented by the arrow A. Each of the arms 8 is generally channel-shaped, i.e. provided with radial channels a, defined between a pair of upstanding ribs 8. These arms 8 are swingable in a plane just below the contacts 2 and perpendicular to the direction of displacement A (i.e. parallel to the plane of the paper in FIG. 2). The actuating means for the carriage 5 is not shown.

To effect swinging movement of the members 8 through the oil-filled zone between the contact pairs 2, 6, the hub 7 is formed with a bushing 9 having a radial cam-follower pin 10 extending into a helical groove b of the cylindrical cam 11, here constituting the drive shaft of the system. The cylindrical cam 11 has a prismatic shank 11a which is nonrotatable when received in the carriage 5 so that, upon displacement of the carriage 5 upwardly (FIG. 1), the arms 8-are swung about the axis of the cam 11 as represented by the arrows B.

Upward movement of the carriage 5 during the contactclosing operation swings the right-hand array of arms 8 in the counterclockwise sense while a downward displacement of the carriage 5 swings the right-hand set of arms 8 in the clockwise sense. The rotary array 7 of arms 8 is provided with a zone 8a free of the nonconductive arms 8, which permits the contact 2 to clear the members 7, 8 in the upper position of the movable contact.

When it is desired to open circuit the switch, the carriages 5 associated with the pairs of fixed contacts 6 are lowered (FIG. 1) so that, as the circuit is opened and an arc is formed between each fixed contact 2 and the countercontact 6, the blades 8 are swept rapidly and successively through the zone of the arc to subdivide the arc during the passage of each arm. Assuming the current waveform does not pass through the zero-amplitude level,

4 the arc is re-established in the gaps between the blades. When, however, the zero level coincides with passage of an arm or is close to the passage of the arm through the zone, re-establishment of the arc is prevented.

Rotation of the blades 8 evacuates ionized products from the arc zone and at the same time pumps centrifugally fresh oil into this zone at high rates from the oil reservoir in which the contacts are located. Preferably, the arms 8 first enter the zone between the contacts 2 and 6 when the distance between them is just approximately equal to the thickness of the blades 8. In the final position of the carriage '5, with the contact 6- at the greatest distance from the contacts 2, the blades 8 are located outside the zone of the arc in their opposite extreme position. Upon movement of the carriage 5 upwardly, the blades 8 are rotated in the opposite sense.

In FIG. 5, I have illustrated another embodiment of the present invention wherein the insulators 23 support channel-shaped stationary contacts 22 which are adapted to receive the knife-blade mobile contact 5. The latter are displaceable upon a support 18 which is shiftable in the direction of arrow C and carries a wedge 17 acting as a cam for displacement of a rod 15 carrying channelshaped arms 14 in a comb-like array. A spring 19 urges the arm 15, which is held between the rails 16, against the "wedge-shaped cam 17. The two arrays of members 14 are driven in opposite directions as represented by the arrow I during contact closing and by the arrow II during opening of the contacts. The speed with which the arc is sectioned and the rate at which the oil is circulated through the gap between the contacts is determined by the rate of opening of the contact at a ratio determined by the angle of inclination of the wedge 17. The springs 19 are attached at one end d to the rod 14 and at the other end e to the guide 16 so that the rod 14 is held against the camming face 0 of the wedge 17.

The improvement described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the appended claims.

I claim:

1. In an oil-break switch having at least one pair of oil-submerged contacts separable in a predetermined direction to generate a circuit-breaking electric are between said contacts through an oil-filled zone, the improvement which comprises arc-quenching means including an array of arc-sectioning oil-entraining members, and means for sweeping said members successively through said zone and between said contacts upon the separation thereof to sweep ionized and ionization products from said zone and fragment arcs bridging the contacts upon separation thereof, said contacts including a fixed contact and a movable contact, said arc-quenching means including support means carrying said members for successive displacement thereof through said zone in at least one plane perpendicular to the direction of displacement of said movable contact, and coupling means operatively connecting said movable contact with said members for sweeping said members through said zone in step with the displacement of said movable contact.

2. The improvement defined in claim 1 wherein said switch comprises a carriage supporting said movable contact and displaceable relatively to said support in said direction, said coupling means including motion-translating means on said carriage co-operating with said members for sweeping same successively through said zone.

3. The improvement defined in claim 2 wherein said members are mounted upon said support means for swinging movement about an axis extending generally in said direction, said motion-translating means including an axially shiftable cam formed with a helical groove carried by said carriage and extending toward said support means,

said members having a cam-follower pin received in said groove for rotation by said cam upon linear displacement thereof in said direction.

4. The improvement defined in claim 2 wherein said members are mounted upon said support means for linear movement in a plane perpendicular to said direction, said motion-translating means including a cam mounted on said carriage and engageable with said members for driving same through said zone.

5. The improvement defined in claim 2 wherein said motion-translating means includes a cam carried by said carriage and cam-follower means on said support c0- operating with said cam.

6 References Cited UNITED STATES PATENTS 932,481 8/1909 Lord et a1. 200151 991,480 5/1911 Christensen 200-151 3,281,561 10/1966 Marx et a1. 200-150 FOREIGN PATENTS 385,478 12/1932 Great Britain.

1 ROBERT S. MACON, Primary Examiner US. Cl. X.R. 200151

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