US2100743A - Circuit breaker - Google Patents

Description

Nov. 30, 1937. F. B. .JOHNSON 2,190,743

CIRCUIT BREAKER Original Filed Jan. 24, 193]. 2 Sheets-Sheet l ffy. z

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CIRCUIT BREAKER Original Filed Jan. 24, 193) 2 Sheets-Sheet 2 12T f7.2 zz Ego? wlTNEssEs; INVENTOR Hede//buE/z/yfon.

www BY WNW t Patented Nov. 30, 1937 PATENT OFFICE CIRCUIT BREAKER Frederick B. Johnson,

Murrysville, Pa., assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Original application January 24, 1931, Serial No.

510,981. Patent No.

2,037,418, April 14, 1936.

Divided and this application March 17, 1936,

Serial No. 69,325

6 Claims.

My invention relates to circuit breakers and more particularly to an arc-extinguishing structure therefor having the capability of opening high-voltage, large-current arcs in air or gas.

The circuit breaker of my invention is of the type in which an arc is drawn and moved into a converging slot in a plurality of spaced conducting plates and split up into a plurality of short arcs. The short arcs are rotated at a high velocity between the conducting plates by reason of the force exerted upon them by a radial eld set up by coils between spaced groups of the plates.

My invention is a further development of circuit breakers of the type shown in the copending application of R. C. Dickinson, Serial No. 511,010, filed Jan, 24, 1931, now Patent No. 1,927,888, issued September 26, 1930, and assigned to the assignee of this application.

rIr'his application is a division of my copending application Serial No. 510,981, led January 24, 1931, and issued April 14, 1936 as Patent No. 2,037,418.

An object of my invention is to provide an arc extinguisher in which the conducting plates between which the arc is rotated by the radial magnetic field have an opening therethrough within the radial eld and in winch the arc may play as a long arc before it is split up between the plates, with means for preventing the short arcs from restriking as a long arc through the openings as it is rotated past the opening by the radial field.

This and other objects and advantages of my invention will be made apparent and more fully understood from the following description of the specific embodiment of my invention illustrated in the drawings, in which Figure 1 is a diagrammatic view, partially in section, of my circuit interrupter.

Fig. 2 is a sectional View, through the circuit interrupter, taken through the deionizing plates on the line II-II of Fig. 3.

Fig. 3 is a sectional View through the deionizing plates, taken on the line III-III of Fig. 2.

Figs. 4, 5, 6, and 7 are side elevational views of the metal plates which are assembled to form the deionizing structure, and

Figs. 8 and 9 are elevational views of the sheets of insulating material which are employed to space apart the metal plates.

Referring to Fig. 1, my circuit interrupter II comprises main contacts I3 and I5, which complete a circuit between conductors I1 and I9, and a pair of arcing contacts 2l and 23 which are connected in parallel with the main contacts I3 and I5. Main contacts I3 and I5 and arcing contacts 2l and 23 are actuated by any suitable operating mechanism so that the main contacts I3 and I5 are opened rst, with practically no arc, and the arcing contacts 2l and 23 are opened later, drawing an arc which is transferred to a pair of stationary arc horns 25 and 21 by means of the moving arc horn 29 which is attached to the moving arcing contact 23. Stationary arc horns 25 and 21 and the moving arc horn 29 are each made of magnetic material, such as iron, to cause a more rapid transfer of the arc due to the attraction thereof to the iron members caused by the local fields set up in the iron by the arc current.

The arcing horns 25 and 21 have arc-terminal portions 3I and 33 and current-conducting portions 35 and 31. The arc horns are each connected in parallel with the main contacts I3 and I through conductors 39 and 4I which are connected to the outer ends of the current-carrying portions 35 and 31. This causes the current to iiow in such direction in each of the arc horns that the magnetic reaction between the fields, due to the current in the arc horns and due to the current in the arc, is such as to cause the arc to be moved upwardly on the horns into the deionizing structure.

The deionizing structure comprises a plurality of groups 43 of main deionizing plates having coil sections 45 therebetween. The deionizing plates and coils are assembled between end plates 41 and 49 which are electrically connected to the upper ends of the arc horns 25 and 21. The plates are secured together by means of a through bolt 5I in an insulating tube 53 of a brous material impregnated with a condensation resin extending through the deionizing structure. The lower portion of the structure is secured together by a pair of tie rods 55 which may be of wood impregnated with a condensation resin having end pieces 51 and which support the lower outer edges of the deionizing plates, as shown in Fig. 2.

As shown in Figs. 2 and 3, each of the groups 43 of deionizing plates comprises a plurality of copper plates 59, each of which is surrounded by an iron plate 6I, which is placed in the same plane in edge-to-edge relation with the plate 59, as shown in Figs. 2 and 7. By having the copper plates 59 in edge-to-edge relation with the iron plates 6I, heat may be conducted from each of the copper plates to one of the iron plates, thus adding the heat capacityof one of the iron plates to the heat capacity of each of the copper plates and making it possible to use smaller copper plates than would otherwise be possible for a structure of the same interrupting ability. Each of the conducting plates 59 has a narrow eXtension 63 extending from the lower end thereof and provided with a narrow converging slot 65. The slot 95 is symmetrical with the main portion of the plate 59 and has a converging tip 61 which curves away from the axis of the plate. Each of the magnetic plates 6| has a wide portion 89 surrounding the body portion of the plates 59 and a narrow portion 1| beside the extensions 63 of the copper plates 59.

In order to prevent warping or buckling of the narrow extension 63, such as would close the slot 65 when subjected to the heat of the arc, each of the copper plates has a projection 'I3 which extends into a cutout portion 16 in each of the iron plates 6|. This interlocks the lower ends of the two plates and prevents movement of the narrow extensions 63 out of proper alignment. Each of the 4copper plates y59 is provided with a slot l5 extending from the center thereof to the outer edge to prevent the flow of eddy currents, thereby reducing the magnetic losses.

The'composite plates formed by the iron plates 5| and copper plates 59 are assembled in groups, the individual plates of which are spaced apart by the insulating members Tl and I9 shown in Figs.,2yandr9 and insulating washers 8| around the opening '94 in the center of each of the copper plates 59. Copper plates 59 are so assembled that `all of the Aplates in each group have the curved portion 6'! of the converging slot curved `to thesame side of the axis of the plates. The slots 'l5 are positioned on opposite sides of adjacent plates throughout each group, thus eliminating the continuous opening through the stack in which the arc could play, which would result if 'the slots 'l5 were on the same side of all of the plates.

The insulating sheets 11 and 'I9 may be of iish paper and so shaped as to provide an annular path 83 in which the arc is rotated. The insulating spacers Tl and 'I9 have depending portions 85 and 89 which define a narrow arc path 9| along the slot 65, and a curved portion `93 which leads the arc into the annular path 83 along a tangent thereto. Insulating spacers 'l1 have 'projections 89 which extend over the tips of the slots 67 and prevent the arc from striking back Ythrough `the slots on each revolution of the arc, as it rotates across the tops of vthe slots. As shown in Fig. 2, the insulating lspacers Il and I9 are made of such width that they over-lap the jointjbetween the conducting plates 59 and the magnetic plates 9| adjacent to the path over which the arc is moved. This prevents the possibility of the jarc playing in the joints between `the plates. Each insulating sheet I9 has a projection 91 defining the upper portion of the annular path and leaving a Ventilating opening 99 leading from one side thereof.

Above the extension 91, is provided a rapidly Ydivergingventilating passage |0| in which the arc `gases 4may expand and come into contact with large lsurfaces of bothV the iron and copper plates,

lwhereby the gas is rapidly cooled andions are re-V moved therefrom.

The arc horns 25 and 27 are formed of spaced sheets of iron having Ventilating passages |03 therebetween. The Ventilating passages |03 permit the 'flow -o-f gas out of the end of the stack ahead ofthe arcas it is moved upwardly on the arc horns and also permit upward ventilation through the stack after the arc has been moved into the spaces between the deionizing plates. It is thus seen that a continuous ventilating passage is provided from the lower end of the arc chamber through the whole deionizing stack. This allows a through flow of gas to .rapidly cool the arc and the plates 59 and 6| so that the heat of the arc is rapidly dissipated, which allows the circuit interrupter to be used for interrupting heavy currents with a duty cycle, which calls for a large number of successive interruptions of the circuit.

The insulating plates 'Il and 19 are assembled in such relation to the copper plates 59 that the curved tips 6l of the slots 65 are aligned, and the direction of rotation of the arc around the annular path 83 is such that the motion of the arc adjacent to the Ventilating opening 99 is in the opposite direction to the iiow of gases out of the passage. This prevents the arc from being blown out of the annular path into the Ventilating passage by reason of the flow of gas through the stack.

The arc is rotated around the annular path 83 by the action of a radial magnetic eld set up by radial field coils |95 which are spaced between adjacent groups 43 of deionizing plates.

As shown in Fig. 1, the directions of the fields, as indicated by the arrows |01, are opposite in alternate groups 43 of deionizing plates. The arc is, therefore, rotated in Vopposite directions in alternate groups of deionizingplates. The positioning ofthe conducting plates 59 and the insulating spacers 'Il and 19 is, therefore, reversed in alternate groups, as is indicated by the broken lines in Fig. 2.

Each of the magnetizing-coil sections 45 comprises a radial eld coil |95 which is placed between a pair of coil-end plates I 99, as shown inA Fig. 5. Each end of each coil |95 is electrically connected to one of the coil-end plates |99. At the lower end of each coil-end plate |99 is positioned a coil-end transfer plate which is spaced from the coil-.end plate |99 by a gap H3.

Each coil-end transfer plate has a converging slot ||5 therein which extends to a point slightly below the gap H3. Each plate |09 has a hole l? through which the bolt for securing the plates together is passed, and a slot ||9 for reducing eddy currents. Y

A number of transfer plates l2! are positioned between the coil-end transfer plates ll! below each of the radial eld coils |95. Each` of the transfer plates |2| has a converging slot |23 similar to the slots I5 in coil-end transfer plates l i l. The transfer plates are spacedapart by insulating spacers |25 of fish paper which have a narrow portion l2'.l to form a path in winch the arc is moved and an enlarged circular portion |29 at the upper end of the passage |27.

At each end. of the stack of plates and radial field coils is an end plate |3| which is electrically connected in the circuit to be interrupted. Plate ISI has an opening |33 for the through bolt 5h and a coverging slot |35 similar to 'the slots |23 and H5, as shown in Fig. 4. Y

As shown in Fig. 2, slots ||5,which are aligned with slots |23 and |35, are shorter and inwardly tapered at a more rapid rate than slots 55 in plates 59. As the arc is moved up into the aligned slots in all cf the plates, the are is irst eonstricted in the tips of the slots l l5, |23 and |35 while still in a relatively wide portion of the slots 55. The arc is then transferred to the coil-end transfer plates I| I and 'transfer plates I2|, splitting the arc into a plurality of short arcs between transfer plates |2| and a plurality of arc sections between plates I I I. Each of the arc sections may be freely moved into the stack because of the width of the slots 65. As the plurality of sections of the arc are moved upwardly, they cross the gap H3 between the coil-end plates |09 and coil-end transfer plates HI. The voltage drop through the radial coils I 35, connected between the plates |09, is smaller than that necessary to maintain the series of arcs between the transfer plates |2| so that the arcs therebetween are extinguished, and the current flows through the radial field coils |05. Since the arc is moving in relatively wide portions of the slots 65 at the time that it crosses the gap H3, there is not much resistance to its movement so that it crosses the gap H3 without serious burning of the coil-end plates |03.

As the arc is moved farther, the slot 'B5 gradually converges so that each of the arc sections is concentrated into an arc of high current density and small cross section. The arc is then above the narrow extensions 1| on the magnetizing pla'tes 6| so that it is no longer acted upon by the blow-in elcl but is within the much stronger eld set up by the radial coils |05 which provide a field of such strength that the arc may be rapidly moved along the tips 61 of the slots 65 and split between the plates 6|. This use of the radial field for splitting each section of the arc into a plurality of short arcs is advantageous in that it is not necessary to provide a blow-in field of such strength as to provide the force necessary to split the arc into a plurality of short arcs. The arc then enters tangentially into the annular path 83 and is rapidly rotated until the occurrence of the zero point on the alternatingcurrent wave when it is extinguished.

As shown in Figs. 1 and 2, a plurality of iron laminations |31 are provided to form extensions of the iron plates 6| beside the arc-drawing contacts and arc horns. The iron laminations |31 are spaced apart by sheets of fish paper |39, shaped similar to the iron plates |31. The lengths of the laminations |31 are varied in different sections of the deionizing structure. The end sections |4I are made of such length as to extend to the arc horns 25 and 21. The section |43 adjacent to the arcing contacts 2| and 23 and main contacts I3 and I5 are made longer than the other sections so as to extend to a point adjacent to the contacts to blow the arc into the deionizing structure. The intermediate section |45 is of a length between those of the other sections so as to extend beside the moving arc horn 29. The provision of iron laminations |31 provides an iron path for the flux set up by the arc current as soon as the arc is drawn, in order to move the arc into the deionizing structure in cooperation with the flux set up by the current iiowing in the arc-terminal portions 3| and 33 of arc horns 25 and 21. The edges of laminated members |31 are protected from the arc by libre plates |41 having arc-resisting inserts |49 of asbestos or other suitable material. An insulating sheet of iish paper I 59 is placed in the joint between the lower edges of the deionizing plates and the iron laminations |31 and also extends between the laminations |31 and fibre plates |41. The iron laminations |31 and fish paper spacers are secured in the structure by being clamped between wood blocks |5| and the fibre plate |41.

A static shield is provided in the form of a pair of sheets |53 of insulating material, such as a fibrous material impregnated with a condensation resin and having sheets of tinfoil |55 embedded therein.

From the above description it is seen that my invention provides an air circuit breaker which is capable of interrupting large currents at high voltages in a most effective manner.

While I have described a specific embodiment of the invention, it should be understood that the various novel features thereof may be used in various combinations, and I am not to be limited by the specific description except as indicated by the scope of the following claims.

I claim as my invention:

1. In an arc extinguisher, a plurality of spaced plates each providing a path about which the arc may be rotated, an opening through said plates in which the arc may play, means for moving the arc from said opening into said path, and means for guiding the arc past said opening as it rotates and preventing it from moving into the opening.

2. In an arc extinguisher, a plurality of spaced plates of conducting material each providing an annular path for the arc, an opening through a plurality of said plates in which the arc may play as a long arc, means for moving the arc from said opening into the plates, thereby splitting it into a plurality of short arcs, and rotating the short arcs about the annular paths, and means of insulating material for guiding the short arcs past the opening through the plates as they rotate and preventing the arcs from restriking through the opening as a single long arc.

3. In an arc extinguisher, a plurality of spaced plates of conducting material each providing an annular path for the arc about which the arc may be rotated more than a whole revolution, a

coil for setting up a radial magnetic iield across said annular arc paths, an opening through a plurality of said plates of conducting material, said opening having a portion within said radial magnetic field, means for causing an arc to play in said opening, and means of insulating material for guiding the short arcs past the opening through the plates as they rotate and preventing the arcs from restriking through the opening as a single long arc.

4. In an arc extinguisher, a plurality of members of conducting material between which the arc may be split up into shorter arcs, said conducting members each providing a recurrent path about which the short arcs may be rotated, a coil for causing a magnetic field for rotating the arcs, an opening through a plurality of said members of conducting material, means for causing an arc to play in said opening, said opening having a portion within the magnetic field for rotating the arc, and insulating means around said opening on the side thereof which is approached by the arc as it rotates to prevent the arc from moving into the opening as it rotates around the recurrent path.

5. In an arc extinguisher, a plurality of spaced plates of conducting material each providing an annular path for the arc about which the arc may be rotated more than a whole revolution, a coil for setting up a radial magnetic iield across said annular arc paths, an opening through a plurality of said plates of conducting material,

said opening having a portion within said radial magnetic field, means for causing an arc to play in said opening, and said coil being energized while the arc plays in said opening in a plurality CII of said plates whereby the radial magnetic -eld set up by the coil moves the arc from the opening into the plates and splits it up into shorter arcs and then rotates the shorter arcs around said annular paths on the conducting plates, and means of insulating material for guiding the short arcs past the opening through the plates as they rotate and preventing the arcs from restriking through the opening as a single long arc.

6. In an arc extinguisher, a plurality of members of conducting material between Which the arc may be split up into shorter arcs, said conducting members eaoh providing a recurrent path about which the short arcs may be rotated, a coil for causing a magnetic field for rotating the arcs, an opening through a plurality of said members or conducting material, means for causing an are to playin said opening, said opening having a portion within the magnetic eld for rotating the arc, said coil being energized while the arc plays in said opening through a plurality of said members of conducting material whereby said magnetic field caused by the coil for rotating the arc is effective for moving the arc from said opening and causing it to'be split up into shorter ares between said members of conducting' material, and insulating means around said opening on the side thereof which is approached by the arc as it rotatesto prevent the arc from moving into the opening as it rotates around the recurrent path.

FREDERICK B. JOHNSON.

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