US 2660640 A
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Description (OCR text may contain errors)
Nov. 24, 1953 s. WOLF 2,660,640
CIRCUIT INTERRUPTER Filed Dec. 6, 1949 Magnetic Material A.G.or 0.0. Gen.
No Magnetic Field Random Particle Position. Non- Conductive State.
Magnetic Field Applied. Conductive Stote.
in Formation Process.
Non- Conductive Stote- WITNESSES: INVENTOR m 5 Samuel Wolf.
Patented Nov. 24, 1953 were CIRCUIT INTERRUPTER Samuel Wolf, Pittsburgh, Pa, assign-or to Westinghousc Electric Corporation, East Pittsburgh, Pa a corporation of Pennsylvania Application December 5, 1949, Serial N 0. 131,395
5 Claims. (Cl. 200-104) My invention relates to circuit interrupters in general, and, more particularly, to interrupting elements therefor.
A general object of my invention to provide an improved circuit interrupter which will more effectively interrupt the circuit therethrough than has been attained heretofore.
A more specific object is to provide an improved circuit interrupter of the type having a pair of electrodes between which is interposed an elastomeric matrix in which is embedded a plurality of magnetizable conductive particles, the conductance of which is responsive to impressed magnetic field.
Further objects and advantages will readily become apparent upon a reading. of the following specification, taken in conjunction with the accompanying drawing, in which:
Figure l somewhat diagrammatically illustrates an improved circuit interrupter embodying invention and shown in the open circuit 330 "tion:
Fig. 2 is an enlarged view showing som what schematically the condition of the elastcineric matrix with the magnetizable particles initially disposed at random throughout the matrix, when no magnetic field is applied.
Fig. 3 is a View similar to that of Fig. 2 but indicating the condition ar sing when a magnetic field is appli d to the elastomeric matrix in the directions YY, as viewed in the drawing; and
Fig. l. is view similar to i, that is with no impressed magnetic field, but with the maguetiz able particles disposed in having an initial orientation due to utilizing a magnetic field in either direction 55 during the time of initial formation of the material.
Referring to the drawing, and more particularly to Figure 1 thereof, the reference numeral l designates a laminated soft iron frame, the two halves of which. also act as electrodes 3. lie" tween the electrodes is an elastic A in which are embedded a plurality of niagnetizable conductive particles (Fig. 2).. The elastic i is preferably an elastomeric matrix or a ruleber-like material. Also a block of insulating material is provided to insulate the two line terminals 2, 3. However, material 5 may he an other mass the same as 4, so the two would be in parallel.
Referring to Fig. 2, it will he observed that with no magnetic field applied a non-conductive condition exists between the terminals 2, 3 with the magnetizable particles 5 distributed at random throughout the matrix i. The particles i may constitute any suitable magnetizable conductive particles such as finely divided iron. nickel, netite and the like. The particles 5 are initially dispersed through the mass t in r..ndorn posi tion. However, in some instances. it 1 ay be desirable to align the particles into chains, said chains extending in the directions X, indicated in Fig. 4., by applying a magnetic field during the initial formation of the matrix, so that all of the chains will be aligned in substantially the same direction along the fiux lines of the magnetic field during the initial formation process. Thus, in the absence of a magnetic field, a non-conductive condition is present as indicated in Figs. 2 and in which no current flow takes place between the pair of electrodes 2, 3. However, upon the application of a magnetic field, say in the directions Y, as indicated in Fig. 3, the particles 5 of i3. 2 or the conductive chains ii of 4 are nightly stressed out of their initial position that they assume a pattern as shown in Fig. 3, in which the particles 5 form conductive cha extend ing between the line terminals 2, E2 in the direetions Y. Immediately upon removal of the magnetic field of Fig. 3, the particles to their original position as indicated in Fig, or the chains 6 return to their position of this condition arising by virtue of the rubber-i e or elastic condition of the elastomeric ma l.
With the principles of my invention thoroughly in mind as a result of an analysis of Figs. 2, 3 and 4, returning again to Fig. 1 it will he noted that I have provided a magnetic field coil l ener" gized by a suitable A.-C. or D.-C. source.
If the random particle material of Fig. 2
is used in Fig. 1,. I preferably employ an axially directed magnetic field as indicated in Fig. 1. Although the field may be A.C. or D.-C., i prefer to use D.-C., since better results are achieved.
If the material lA of Fig. 4 is employed in Fig. 1, that is with the chains 5 initially aligned in the directions X by application of a mag netic field in the initial formation process of the material All, then I prefer to use an externally impressed magnetic field that is substantially in the direction of a straight line extending between the line terminals 2, 3. Here again, however, the field may be A.-C. or l3.-C., but preferably I use a D.-C. field.
The front contacts iii of a contactor H are provided to control the encrgization of the wine-- ing 1. The circuit for energizing the coil 12 for closing the contaotor H extends from the control line Ll through the coil i2 to the coil l3 of a disconnect switch M, which when opened interrupts the passage of any residual cur'ent through the interrupter following removal of the magnetic field. The disconnect switch M has a pair of front contacts 15 and a closed turn Hi, the latter insuring a slow opening of the contacts l during the opening operation of the interrupter, until after such a time at which the magnetic field has been removed and the particles 5 will have assumed the position shown in Fig. 2 or 4:. This will insure breaking the circuit within the mass 4 and not at the contacts [5.
An opening button H is provided in circuit with the windings l2, l3 and a closing button It is by-passed by front contacts H] of the contactor II.
The operation of the interrupter of my invention will now be explained. Initially the conditions are as shown in Fig. 1 with the disconnect switch 14 open and with the winding 1 deenergized. The particles assume the condition shown in Fig. 2 or Fig. t and no current passes through the interrupter. To send current through the interrupter, one closes the closing button l8 by any suitable means. This energizes the coils l2, l3 across the control lines Ll, L2. The disconnect switch M closes after the contactor II by virtue of the operation of the oneway acting dashpot 20. This prevents application of line voltage to the interrupter until the particles 5 or chains 6 have assumed their conducting positions. Otherwise sparking might occur within the material 4 if voltage were applied to the mass 4 at the same time as the field was applied.
The closing or the contactor H closes the front contacts l0 energizing the winding 1, and also closes the front contacts 19 by-passing the closing button 18, so that the latter may be mo mentarily operated.
The energization of the winding 7 through the closing of the front contacts 10 of the contactor ll sets up magnetic field as indicated by the flux lines 5 to thereby stress the elastomeric matrix. 4 and cause the chains 6 embedded therein to be stressed out of their original condition as in Fig. 4, or the particles 5 from a completely random position. as in Fig. 2. This leads to the conductive condition indicated in Fig. 3 where the particles 5 align to form the conductive chains 6 extending between the electrodes 2, 3.
When the physical alignment as idealized in Fig. 3 occurs, the circuit interrupter is closed by virtue of the closing of the delayed acting disconnect switch. and current passes therethrough. To open the circuit through the interrupter, the opening button ll is pressed to deenergize the windings l2, it. The contactor H, when deenergized, opens, breaking the circuit through the winding 1 to remove the magnetic field 5 and to thereby cause the particles 5 to be forced back into their original position as indicated in Fig; 2 where a non-conductive state exists. Because of the closed turn 26, the disconnect switch M. is slow in opening so that the non-conductive condition of Fig. 2 is sure to be in existence before opening of the disconnect contacts (5. The opening of the disconnect contacts l5 insures the interruption of any residual current passing through the interrupter following removal of the magnetic field.
I shall now give three examples of materials which may be used for the matrix 4 or AA. Suit able elastomeric materials for such use are natural rubber or synthetic elastomers such as polychloroprene, butadiene, styrene copolymers, butadiene-acrylonitrile copolymers, silicone elastomers and the like. A mixture was prepared from 20.8 parts of electrolytic iron particles of an average diameter of microns, 9 parts of a dimethyl silicone fluid of a viscosity of 10,000 centistokes and 0.4 part of butyl perbenzoate. The mixture was molded under a pressure of 500 p. s. l. and a temperature of C. for twenty minutes to produce an elastomeric resistance mass.
Another example was prepared by taking 49.5 parts by weight of electrolytic iron of a fineness of 230-270 mesh, 16.5 parts by weight of dimethyl silicone fluid of a viscosity of 10,000 centistokes and 0.33 part byweight of butyl perbenzoate. This mixture was molded under a pressure of 300-500 p. s. i. and a temperature of 150 C. for twenty minutes to produce an elastomeric resistance mass. A sample of the resultant material interrupted 20 amperes at 83 volts.
Another example was to take 26.6 parts by weight of electrolytic iron of a fineness of 230-270 mesh, 13.3 parts by weight of a dimethyl silicone fluid of a viscosity of 10,000 centistokes and 0.27 part by weight of butyl perbenzoate. The mixture was molded under a pressure of 500 p. s. i. and a temperature of 150 C. for twenty minutes to produce an elastomeric resistance mass.
From the foregoing description of my invention, it will be apparent that I hav provided an improved circuit interrupter in which an elastomeric or rubber-like matrix is employed in which is embedded a plurality of magnetizable conductive particles 5. The matrix extends between the electrodes 2, 3 and depending upon the existence of a magnetic field forms a conducting or non-conducting state between the electrodes 2, 3. hviously other control arrangements than that disclosed herein may be employed without departing from the scope of my invention.
Although I have shown and described a specific structure andmaterials, it is clearly to be understood that the same was only for the purp se of illustration, and that changes and modifications may readily be made therein without departing from the spirit and scope of the appended claims.
I claim as my invention:
1. A circuit interrupter including a pair of fixed electrodes, an elastic mass including finely divided iron particles disposed in chains em bedded in an elastomeric matrix with the chains generally aligned in an elastic direction. other than that assumed by a straight line extending between the electrodes, means for applying a magnetic field in a direction substantially parallel to the direction assumed by a straight line extending between the electrodes, the impressed magnetic field causing the chains to be stressed out of their original position to a position in which the elastic mass as a whole is rendered conductive, and means for removing the magnetic field to thereby cause said elastic mass to return to its non-conductive state relative to said electrodes.
2. A circuit interrupter including a pair of fixed electrodes, an elastic mass including finely divided magnetisable particles disposed in chains embedded in an elastomeric matrix with the chains generally aligned in a direction other than that assumed by a straight line extending between the electrodes, means for applying a magnetic field in a direction substantially parallel to the direction assumed by a straight line extending between the electrodes, the impressedmagnetic field causing the chains to be stressed out of their original position to a conductive position, and means for removing the magnetic field to thereby cause said elastic mass to return to its non-conductive state relative to said electrodes.
3. A circuit interrupter including a pair of spaced electrodes, an insulating elastic solid body interposed between said electrodes and having finely divided conducting magnetic particles interspersed therein, the conducting magnetic particles being spaced in substantially non-conductive relation so that the elastic body has a relatively high resistance between the electrodes, means for applying a magnetic field to the elastic body and the particles then being in good-conducting relation with respect to each other to form thereby conducting chains between the electrodes, said elastic solid body being stressed while the magnetic field is applied so that removal of the magnetic field causes, due to the elastic nature of the solid body, a return of the particles to their initially substantially non-conductive relation in which high resistance exists through the finely divided particles between the electrodes.
4. A circuit interrupter including a pair of spaced electrodes, a rubber-like solid insulating substance disposed between said electrodes and forming an elastomeric matrix having finely divided conducting magnetic particles interspersed therein, the finely divided conducting magnetic particles making relatively poor contact so that the interrupter carries no appreciable current from one electrode to the other, means for eX- ternally impressing a magnetic field to the solid substance to reorient the finely divided particles against the resiliency of the solid substance, said particles then being positioned in good-conducting relation with adjacent particles and permitting current flow between the electrodes, and removal of the magnetic field effecting a return of the finely divided particles to their initial nonconducting state due to the elasticity of the rubber-like solid substance.
5. The combination in a circuit interrupter of a pair of spaced electrodes, an elastic insulating solid disposed between the electrodes, finely divided conducting magnetizable particles disposed in chains interspersed within the solid with the chains generally aligned in a direction other than that assumed by a straight line extending between the electrodes, means for applying a magnetic field in a direction substantially parallel to the direction assumed by a straight line extending between the electrodes, the impressed magnetic field causing the chains to be stressed out of their original position to a conductive position between the electrodes, and a removal of the magnetic field causing the chains to reform in their initial condition due to the elasticity of the solid giving rise to a non-conductive state between the electrodes.
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