US2687500A - Circuit interrupter - Google Patents

Description

Aug. 24, 1954 WITNESSES:

awe (225 Filed Dec. 6, 1949 No Magnetic Field, Non-Conducting State C. H. JONES ET AL CIRCUIT INTERRUPTER l7 Fig.6.

Magnetic Field Applied Conducting State INVENTORS Charles H. Jones a George W Nogel.

Patented Aug. 24, 1954 CIRCUIT IN TERRUPTER Charles H. Jones and George W. Nagel, Pittsburgh, Pa assignors to Westinghouse Electric Corporation, East tion of Pennsylvania Pittsburgh,

Pa., a corpora- Application December 6, 1949,-Serial No. 131,412

9 Claims.

align the magnetic particles into'conductive magnetic chains extending between the terminals forming conductive paths for the current iiow therebetween.

Another object is to provide a new circuit interrupting arrangement by agitating .a medium-containing magneticparticles aligned to conduct a current so as to disperse the magnetic particles following removal-of an aligning magnetic field.

Another object is to ,provide an improved circuit interrupter utilizing a dielectric liquid in which is dispersed particles and toemploy a magnetic field to-align the magmediately preceding paragraph in which improved agitating means are provided to disperse the magnetic particles following removal of the magneticfield.

Another object is to provide an improved circuit interrupter employing magnetic particles disposed .in a non-rigid, non-conducting medium with a magnetic field for aligning the magnetic particles into conductive chains extending between'the-electrodes, andto utilize therewith disconnect means for interrupting any residual currentthrough the interrupter following removal of the magneticfield.

Still another'object is to provide an improved circuit interrupter of the alternating-current type in which'improved magnetic means are employed to -more effectively bring about circuit interruption at a current zero.

Circuit interrupters of the prior art have depended upon various agencies for eifecting circuit interruption. In some of them, reliance has been placed .upon speed in separating the movable contacts. In others, reliance has been placed our invention is to provide upon blow-out coils, which necessarily introduced complications, and in still 'otherinterrupters the arc has been broken into a series of shorter serially related arcs which were rotated upon coolsurfaces to bring abouttheir interruption.

:It-is obvious that circuit'breakers built to carry hundreds or thousands of amperes continuously musthave heavy contacts and so require strong springs to get the contacts separated rapidly enough. The maximum practical speed used is about 2% feet a second. Sometimes it was deemed necessary .to have a plurality of breaks inseries so as to increase the effective contact separationspeed'of the breaker taken as a whole. However, in-such cases, the maximum speed was onlyabout 20 feet per second.

In other interrupters disclosed by the prior art, compressed gas has been used at pressures ranging from to 300 pounds per-square inch for opening the contacts and blowing a blast of gas at'the drawn arc to effect the extinction thereof. In suchcases, the breakers used 15 to 25 cubic feet of air each time the circuit was opened.

In the circuit interrupter of'our invention, no heavy'springs are employed and no compressed gas for moving the contacts is employed because incur invention the contacts do not move com pletely together in the closed circuit'position of the interrupter.

Further-objects and advantages will readily be come apparent upon reading the following specification taken in conjunction with the drawing, in-which:

Figure 1 illustrates somewhat diagrammatically a circuitinterrupter embodying our invention and shown in the open circuit position;

Fig. 2 illustrates another form of circuit interrupterembodying our invention and shown in the open circuit position;

Fig. 3 illustrates still a further embodiment of our invention, the interrupterbeing shown in the open circuit position;

Fig. 4 illustrates a circuit interrupter embodying our invention and utilizing an improved magnetic control scheme to effectively brin about circuit interruption at a current zero on the alternating-current wave.

'Fig. 5 diagrammatically illustrates a pair of electrodes with the circuit being open because of an absence of-a magnetic field; and

Fig. 6 isa view similar to that of Fig. 5 but illustrating the conditions existing following an application ofthe magnetic field.

.Referringto the drawing, and more particularlyto Figure 1 thereof, the reference numeral l designates an insulating tank or container in which is disposed a suitable mixture 2 or a nonconducting medium such as oil and a magnetic powder. The mixture l fills the space between the electrodes 3, 4.

In our invention, any finely divided magnetizable conducting powder may be used in the dielectric medium. The powder may be iron, nickel, silicon iron, magnetite, etc. The dielectric medium may be oil, wood fiour, finely divided rubberized particles, alkyl phosphates, chlorinated diphenyl, dibutyl sebacate, or other non-rigid, non-conducting materials in which the magnetic conducting particles may be dispersed.

It is only necessary that the non-conducting material be movable as by being fluid or finely divided, that is, the particles or which are comparable with the size of the magnetic particles. Also the particles should be somewhat freely movable so that there will not be too much resistance to motion of the magnetic particles in the resultant mass.

Referring to Fig. 5 for an understanding of the principles applicable to our invention, it will be noted that when no magnetic field is applied, the magnetic particles 5 are distributed in random position in the space between the electrodes 3, l. However, upon an application of a magnetic field applied to the space between the electrodes 3, 4, as shown in Fig. 6, the magnetic particles 5 align themselves into chains 6 forming conductive paths between the electrodes 3, 4. The magnetic field may result from an A. C. or D. C. source, and may be in any direction. Preferably, however, a D. C. field is used with a direction of the D. C. field taken parallel to a straight line connecting the electrodes 3, A.

It is apparent upon an inspection of Fig. 6 that the existence of the several conductive chains 6 leads to a condition in which current flow is easily obtained between the spaced electrodes 3, l.

Referring again to Fig. 1, it will be observed that we have provided means for establishing a magnetic field including an energizing winding 1 in series with the front contacts 8 of a contactor 9. An A. C. or D. C. source H] is interposed in the circuit including the energizing winding 1 so that when the front contacts 3 of the contactor 9 close, a magnetic field will be set up within the container i, an iron shell I! being provided to intensify the magnetic field. The formation of such a magnetic field will cause the magnetic particles 5 to be attracted and to form chains along the lines of magnetic flux and thus drawn into close physical contact. The flux density will determine the massiveness of the chains and thus the conductivity of the mixture.

To insure a dispersal of the magnetic particles 5 within the oil or other non-conducting medium following removal of the magnetic field, we provide a mechanical agitator, in this instance comprising motion of the electrodes 3, 4. They are moved inwardly by solenoids l2, l3 and outwardly following deenergization of the solenoids l2, [3 by compression springs l4, l5. The compression springs l4, l5 seat at one end on the tank I, and at the other end on washers 16, ll movable with the electrode rods l8, l9. Thus, energization of the solenoids l2, l3 will move the electrodes toward each other a short distance compressing the springs H3, H3. Deenergization of the solenoids l2, 13 will permit the compression springs l4, [5 to force the electrodes 3, l outwardly mechanically agitating the mix 2 and thereby dispersing the particles 5 within the oil. Such agitating motion of the electrodes 3, 4 within the tank l breaks the adherence between the particles 5, constituting the chains 6, and causes the mixture to be rendered non-conductive.

To effectively prevent the passage of any residual current in the open circuit position of the interrupter, as shown in Fig. l, we provide an external disconnect switch 20. The operation of the disconnect switch 20 is synchronized with the operation of the interrupter by having the energizing coil H of the disconnect switch 20 in series with the coil 22 of the contactor 9. Preferably, a normally closed push-button 23 is provided in series with the winding 2| which is energized from the line L2. Also, a normally open push button 24 is included in the circuit to the winding 2! which is bypassed by front contacts 25 of the contactor 9.

The disconnect switch 23 has a delayed closing furnished by the dashpot 26, so that on closing the interrupter the chains 6 will have had time to form before an impressing of line potential to the electrodes 3, 4. This eliminates the possibility of sparking within the mix 2 which otherwise might occur. The disconnect switch 20 also has a delayed opening provided by the closed turn 2i. Consequently, the disconnect switch 20 will drop out on the opening operation of the interrupter after the opening of the contactor 9. This insures opening the circuit within the mix 2 following removal of the magnetic field and by the mechanical agitation process, and not at the disconnect switch contacts 28. The latter, of course, are not suitable for breaking currents of appreciable magnitude, but are capable of interrupting any small residual current remaining following the main interruption process.

The operation of the interrupter is as follows. During the closing operation, one manually presses the closing button 24. This energizes the coils El, 22 of the disconnect switch 20 and contactor 9 respectively across the control lines Ll, L2. Also, the solenoids i2, i3 are energized at the same time through the back contacts 29 of the contactor 9.

Since the contactor 9 is slow closing by virtue of the dashpot 39, the solenoids are energized and the electrodes 3, l move toward each other compressing the springs l4, [5 before the contacts 8 close energizing the magnetic field. Consequently, when the contacts 8 do close energizing the magnetic field the compression springs l4, [5 are already compressed at this time, and the electrodes 3, 4 are in their inward position.

The energization of the magnetic field by the closing of contacts 8 freezes the mix 2, preventing retraction of the electrodes 3, 4 even though the solenoids l2, l3 are deenergized by opening of the contacts 29. The wiping contacts 29 open after contacts 8 have closed. A short time after closing of the contacts 8 energizing the magnetic field, the disconnect contacts 28 close applying line potential to the interrupter. The circuit is then closed through the interrupter, with the electrode solenoids l2, l3 deenergized, and compression springs l4, l5 compressed.

The electrical circuit through the interrupter itself includes the external disconnect switch 20 (the contacts 28 of which are now closed), electrode 3, conductive chains 6, to electrode 4 and hence to external circuit connection 31.

To: openzthe interruptergxitcisfimerely n'ecexary tot push the opening buttonlfi whichiisnormally closed;- Thezopening orith'eino'rmally'closed push buttonizii 'will brealc the electricalicircuitthrough thewindings zl', 2-24to d'eenergize the contactor 9 and cause ani opening of: the circuit through the field winding 1Ito remove the magnetic field; The mix: williunfreeze and permit the springs I4, I to: force the: electrodes 3, 4 apart, thereby agitating 'thamixto disperse the magnetic particles 5 in the oil to break the-conductive chains 6.

I he' closed turn 2 -l-isiprovided in the: disconnect switch" 20 to delayopeningof the contacts 2 8: until after the chains G have been broken by tha -agitating separating movement of the electrodes'3 4-.

Referring to Fig. 2 it will be apparent that certain' features are similar t'o those pr vio ly d closedi inFigi '11 The container la may, as before, be agitated, but in this instance byan agitatbr=or paddle wheel 32 The. electrode 3a is disposedwithin the'container I a andthe container la itselfimay' constitute the other electrode 4a which may be connected to the external circuit 31' In" this embodiment, aniron yoke member 33 is employed, beingsurrounded by an energizing winding 'ls, havingthe same function as the coil l of Fi'g; 1. The winding Isis energized by a source I0 and contacts 8 of a contactor 9, the latter not being shown. The method of operation is the same as that previously described, and hence-it: will notbe repeated. The operation of the paddle wheel 32' may be the same as that clearly shown' in Fig. 3-, which showsanother embodiment ofour invention, and which will now be described.

The pa'ddle wheel32 ofFig. 3 is on a shaft 34 having a-pinion gear 35at the external end thereof% Theshaft 34 doesnot obstruct the i'nterelectrode'space. A rack 36 is biased downwardly by a"-- tension spring 3T and is moved upwardly in oppositionto thetension spring 31 by a solenoid I35 The circuit for thesolenoid I 3-may be the same as-inFig. l; The disconnect switch 28 is in series with the electrode 3b, which in this instance is constituted by a yoke member 38 of magnetic material; such as iron and disposed within the enclosure lb: The other electrode 41) is preferably constituted by a similarly shaped member 39. windings-la, 1b are employedhaving the same function'as'the winding 1 ofFig. 1, and being energized from suitable sources Illa, I072. The normally open: contacts 8a, 8b in series respectively-withthe windings 1a, 1b are preferably simultaneouslyoperated by any suitable means so-tli'at uponthe formation of a magnetic field between theends of theyoke members 38, 39, conductive chainsii may be. formed therebetween to complete the circuit. The control scheme may be thatas indicated heretofore in connection with Fig: 1;

InTig. 4' wehave shown a container I similar iir typeto'thatofl ig; lwi'th a similar meansfor agitation; In this embodiment of our invention, however, we provide two cooperating magnetic fields, each'disposed at right angles to the other. One'ma'gnetic field, herein. called the control field, istransverse'of the container I and is set up by twofield windings 1a, 1b electrically in series andcontrolled by'the contacts 8 as in Fig. 1. The other magnetic field is axially of the container l, and' is set' up by'the series" coil 40; Alternating current fiows=through the'm'aincircuit 3|. Preferablyriron cores 4''! 42 areproviddfor the windi 3, 4 by the adherence of the particles ingsi Ta 'lb' to' lowerthe reluctance of the mag netlc circuit;

The device functions as follows. longastlie' control fieldis present, aconducting sta-te'exists' within the container I; The two-fields merely add vectorially and current passes-between the electrodes 3'; 4-; Whenit is desired-to interrupt the current-flowthrough the interrupter, the con-- trol-fi'el'd is'cut'off by pressing the open button 23} as" heretofore explained inconnectionwith Fig. l'; The control-fieldgoes-to zero, but if the instantaneous value ofthe current through the series'winding du ishig-h, there will still exist arelatively "high" value *of magnetic field within the container l I to 1 cause the continuance of-' the existence-- of theconductive chains 6.- When the instantaneous value-oftheseries circuit current goes to-zero, theauxiliary magnetic field set up by the series winding 4zl"will also-g0 to Zero, the mixwill unfreeze and'at the'--zero-point"on'the' alternating' current'wave the particles willbe dis pers'ed b'y the agitating movement ofthe elec-' trodes 3} 4f Thus, in Fig. 4 we-havedisclosed a magnetic control arrangement in which interruption of the circuit takes place-effectively at a current zero on thealternating-current wave;

From the-foregoingdescription of several em-- bodimentsof'our'invention, it will be apparent that we have provided an improved magnetic fluid type' ofcircuit interrupter in which thecir cuit is eifectively opened and 1 closed. When the magnetic fieldis present, as in'Fig. 6; conductive paths G-are caused to form between the electrodes- 5 to' ea'ch other andtotheeliactrodes3} 4.' Upon the removal ofthe magnetic field, the agitation process'may bedependedupon to'break thechains B and' render" themixture 2" non-conducting by dispersing the magnetic particles 5- within the-oil, thereby break ing the chains 6.

The'dielectric medium-need not be oil, but may be any suitable non-rigid, non-conducting medium; Clearly other devices for agitating'the mix may be employed. Those described were merely'for purposes of illustration. The discon nectmeans insures breakage of any residualcurrent passing through the device.

Although we'have shown and described specific structures, it'is to be clearly understood that the same were merely forthe purpose of illustration, and that changes and modifications may readily be made therein by those skilled-in the art without departing'from the spirit and scope of the appended claims.

We claim as our invention:

1. A circuitinterrupter including a container containinga magnetizable powder disposed in a' dielectric liquid, a pair of electrodes associated with the container in contact with the dielectric liquid between which current may flow and be interrupted, means for establishing a magnetic field within the dielectric liquid to establish a conductivecondition therein between the electrodes, means for removing the magnetic field to establish a non-conductive state in the region between the electrodes, disconnect means serially connected with the electrodes, means for closing the disconnect means during the closing operation only after establishment of the magnetic field within the dielectric liquid, and means for opening said disconnect means only after removal of the magnetic field within the dielectric liquid to establish a non-conductive state therein.

2'..A circuit interrupter'including acontainer 7 containing an iron powder disposed in oil, a pair of electrodes associated with the container in con. tact with the oil between which current may fiow and be interrupted, means for establishing a magnetic field within the oil, an agitator for dispersing the magnetic powder within the oil disposed in the container following removal of the magnetic field to break the conductive chains of magnetic powder extending between the two electrodes, disconnect means serially connected with the electrodes, means for closing said disconnect means during the closing operation only after establishment of the magnetic field, and means for opening said disconnect means during the opening operation only after removal of the magnetic field.

3. A circuit interrupter including a container containing a magnetizable powder disposed in a dielectric liquid, a pair of electrodes associated with the container in contact with the dielectric liquid between which current may fiow and be interrupted, means for establishing a magnetic field within the dielectric liquid, a mechanical agitator utilizing motion of at least one electrode for dispersing the magnetizable powder within the dielectric liquid disposed in the container following removal of the magnetic field to break the conductive chains of magnetic powder extending between the two electrodes, disconnect means serially connected with the electrodes, means for closing said disconnect means during the closing operation only after establishment of the magnetic field, and means for opening said disconnect means during the opening operation only after removal of the magnetic field to establish an open circuit condition.

4. A circuit interrupter including finely divided magnetic particles dispersed in a non-rigid nonconducting medium, a pair of electrodes disposed in said medium, means for establishing a magnetic field in the medium to form conductive magnetic chains of the magnetic particles between the electrodes to establish current flow therebetween, spring means biasing at least one electrode, means for causing motion of the electrode and for energizing the spring means prior to the establishment of said magnetic field, and the deenergization of the magnetic field permitting the spring means to cause motion of the electrode to result in agitation of the particles, thereby dispersing them within the medium to break the conductive chains of magnetic particles extending between the two electrodes.

5. An alternating current circuit interrupter including a mix of finely divided conducting magnetic particles dispersed in a non-rigid, nonconducting medium, a pair of spaced electrodes having the mix therebetween, means other than the controlled main circuit for establishing a magnetic control field in the mix at will to bring about current flow through the interrupter by a formation of conducting chains of the particles, means for discontinuing said magnetic control field at will, and a series coil in which flows at least a portion of the series current disposed in such proximity to the mix to set up an auxiliary magnetic field therein responsive to the series current, whereby upon removal of the control field the auxiliary magnetic field will tend to maintain the mix in a conducting state until near a current zero on the alternating current wave.

6. An alternating current circuit interrupter including a mix of finely divided conductin magnetic particles dispersed in a non-rigid, non-conducting medium, a pair of spaced electrodes having the mix therebetween, means otherthan the controlled main circuit for establishing a magnetic control field in the mix at will to bringabout current fiow through the interrupter by a formation of conducting chains of the particles, means for discontinuing said magnetic control field at will, a series coil in which flows at least a portion of the series current disposed in such proximity to the mix to set up an auxiliary magnetic field therein responsive to the series current, whereby upon removal of the control field the auxiliary magnetic field will tend to maintain the mix in a conducting state until near a current zero on the alternating current wave, and the control and auxiliary magnetic fields being oriented at a substantial angle with respect to each other so that the fields will not cancel each other to permit cessation of current flow other than near a current zero on the alternating current Wave.

7. An alternating current circuit interrupter including a mix of finely divided conducting magnetic particles dispersed in a non-rigid, nonconducting medium, a pair of spaced electrodes having the mix therebetween, means biasing one electrode to move, means other than the controlled main circuit for establishing a magnetic control field in the mix at will to bring about current fiow through the interrupter by a formation of conducting chains of particles within the mix, means for discontinuin said magnetic control field at will, means for causing motion of said one electrode and for tensioning said biasing means prior to the establishment of said magnetic control field, a series coil in which flows at least a portion of the series current disposed in such proximity to the mix to set up an auxiliary magnetic field therein responsive to the series current, whereby upon removal of the control field the auxiliary magnetic fieldwill tend to maintain the mix in a conducting state until near a current zero on the alternating current wave at which time the biasing means will cause said one electrode to move and in so doing will disperse the magnetic conducting particles to effect the nonconductingstate.

8. An alternating current circuit interrupter including a mix of finely divided conducting magnetic particles dispersed in a non-rigid, non-conducting medium, a pair of spaced electrodes having the mix therebetween, means biasing one electrode to move, means other than the controlled main circuit for establishing a magnetic control field inthe mix at will to bring about current fiow through the interrupter by a formation of conductin chains of particles within the mix, means for discontinuing said magnetic control field at will, means for causing motion of said one electrode and for tensioning said biasing means prior to the establishment of said magnetic control field, a series coil in which flows at least a portion of the series current disposed in such proximity to the mix to set up an auxiliary magnetic field therein responsive to the series current, whereby upon removal of the control field the auxiliary magnetic field will tend to maintain the mix in a conducting state until near a current zero on the alternating current wave at which time the biasing means will cause said one electrode to move and'in so doing will disperse the magnetic conducting particles to effect the non-conducting state, and the control and auxiliary magnetic fields being oriented at a substantial angle with respect to each other so that the fields will not cancel each other to permit cessation of current flow other than near a current zero on the alternating current wave.

9. An alternating current circuit interrupter including a mix of finely divided conducting magnetic particles dispersed in a non-rigid, non-conducting medium, a pair of spaced electrodes having the mix therebetween, means other than the controlled main circuit for, establishin a magnetic control field in the mix at will to bring about current flow through the interrupter by a formation of conducting chains of the particles within the mix, means for discontinuing said magnetic control field at will, agitator means, means tensioning said agitator means prior to the formation of conducting chains within the mix, the formation of the chains within the mix maintaining the tensioning of the agitator means and renderin the same motionless, means for estabtain the conducting chains within the mix until near a current zero, at which time the agitator means will be released and move under the efiect of the tensioning means to eiiect dispersal of the particles.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 428,653 Thomson May 27, 1890 543,892 Potter Aug. 6, 1895 711,123 Rhoades Oct. 14, 1902 716,334 De Forest Dec. 16, 1902 811,654 Murphy Feb. 6, 1906 1,380,752 Toomey June 7, 1921 1,835,612 Pearson Dec. 8, 1931 1,963,496 Land June 19, 1934 2,265,203 Six Dec. 9, 1941 2,288,050 Vatter June 30, 1942 2,500,953 Libman Mar. 21, 1950 FOREIGN PATENTS Number Country Date 31,883 Denmark Sept. 23, 1920

Images