US3395372A - Low current or voltage circuit breaker - Google Patents

Description

July 30, 1968 H. L. @PADI 3,395,372

LOW CURRENT OR VOLTAGE CIRCUIT BREAKER ZU\ FIG. 4.

ze 3/ 23 30 36 x INVENTOR. HENRY l.. OPAD ATTORNEY July 30, 1968 H. oPAD 3,395,372

LOW CURRENT OR VOLTAGE CIRCUIT BREAKER Filed May 22, 1967 2 Sheets-Sheet 2 H ,f C. I 8 /5 Fles. l c Mal? INVENTOR.

HENRY L. OPAD BYZ.;

ATTORNEY United States Patent1 O r 3,395,372 LOW CURRENT OR VOLTAGE CIRCUIT BREAKER Henry L. pad, 245 Bennett Ave.,

New York, N.Y. 10040 Filed May 22, 1967, Ser. No. 640,192 7 Claims. (Cl. 335-174) ABSTRACT OF THE DISCLOSURE A circuit breaker having a handle connected to a movable contact through a toggle mechanism and being movable to an ON position to engage the movable contact with a fixed contact so long as the toggle mechanism is in extended condition, is provided with an actuating arm connected to a I.permanent magnet which is attracted to the core of a solenoid so as to move the arm to a tripping position for collapsing the toggle mechanism and thereby tripping the circuit -breaker or preventing closing of its contacts. either when a direct current flowing in the solenoid coil in the direction producing a magnetic ux opposed to that of the permanent magnet is less than a predetermined value or when a direct current is made to flow in such coil in the opposite direction. Further, a fixed member of magnetic material may be disposed to magnetically latch the magnet away from the solenoid core at a position corresponding to an inoperative position of the actuating arm until a direct current ilows through the solenoid coil to produce a magnetic ux attracting the magnet to the core.

This invention relates to circuit breakers, and more particularly is directed to circuit breakers which are adapted to be tripped or to prevent closing of their contacts so long as the current flowing in an associated circuit, or the voltage impressed on such circuit is below a predetermined value.

Circuit breakers have been provided, for example, as disclosed in U.S. Patent No. 2,690,486, issued Sept. 28, 1954, to K. W. Wilckens, in which a handle is connected to a movable contact through a toggle mechanism to engage the movable contact with a fixed contact upon displacement of the handle from an OFF position to an ON position so long as the toggle mechanism remains in an extended condition. Such circuit breakers further have an actuating arm engaged by a spring to an inoperative position and forming part of an armature that is magnetically attracted by a solenoid, in response to an overload condition in an associated circuit, to displace the actuating arm to a tripping position where it causes collapsing of the toggle mechanism, for example, by acting on a latch thereof, thereby to trip the circuit breaker or prevent closing of its contacts so long as the overload condition persists.

Such existing circuit breakers obviously permit the controlled circuit to lbe made or interrupted by manipulation of the circuit breaker handle without regard to the magnitude of the current flowing in a monitored circuit or of the voltage impressed thereon so long as an overload is absent. However, there are numerous applications of circuit breakers in which it is desirable, or even necessary, that the circuit breaker be tripped or prevented from closing its contacts in response to either an inadequate current in an associated circuit or an inadequate voltage irnpressed on such circuit. Further, there are many applications where it is desirable to either permit or bar the making or interrupting of a controlled circuit by manual actuation of the circuit breaker in response to suitable electrical signals from a monitored circuit.

Accordingly, it is an object of this invention to provide 3,395,372 Patented July 30, 1968 venting the completion of a controlled circuit so long as there is an inadequate current in a monitored circuit or an inadequate vvoltage impressed thereon, which monitored circuit may be the same as, or separate from the controlled circuit.

Another object is to provide a circuit breaker having the foregoing characteristics which is inherently failsafe in its operation, that is, which is tripped or prevented from closing its contacts whenever there is a failure in its coil or in the wiring connecting the same to the associated circuit.

Still another object is to provide a circuit breaker of the described character which can be mounted in any position without affecting the reliability of its operation.

A further object is to provide a circuit breaker which is adapted to be tripped or :prevented from closing its contacts when the current flowing in a monitored circuit is below a minimum value and which can be mechanically or otherwise coupled with a standard over-current circuit breaker to permit closing of the coupled-together circuit breakers only when the monitored current is within predetermined limits.

Still another object is to provide a circuit breaker which may be controlled by electrical signals to either permit or bar the making or breaking of a controlled circuit by manual actuation of the circuit breaker.

In accordance with an aspect of this invention, a circuit breaker of the type having a handle connected to a movable contact through a collapsible linkage, for example, a toggle mechanism, and being movable to an ON position to engage the movable contact with a fixed contact so long as the linkage is in an extended condition, is provided with an actuating arm connected to a permanent magnet which is attracted to the core of a solenoid, to move the arm to atripping position for collapsing the linkage and thereby tripping the circuit breaker or preventing closing of its contacts, either when a direct current of less than a predetermined value ows in the solenoid coil in the direction to repel the magnet or when a direct current flows in such coil in the opposite direction.

In accordance with another aspect of the invention, a circuit breaker, characterized as above, is further provided with a xed member of magnetic material disposed to magnetically latch the magnet away from the solenoid core, and thereby dispose the actuating arm at an inoperative position, until a direct current signal fiows through the solenoid coil in the direction to magnetically attract the magnet to the core.

The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of illustrative embodiments thereof which is to be read in connection with the accompanying drawings, wherein:

FIG. l is a side elevational view of a circuit breaker embodying this invention which is shown with its case broken away and in section;

FIG. 2 is an enlarged fragmentary sectional view showing details of a toggle mechanism included in the circuit breaker of FIG. l;

FIGS. 3 and 4 are side elevational views of the operating components of the circuit breaker of FIG. 1, but shown in two successive stages during the tripping thereof;

FIGS. 5, 6 and 7 are schematic views illustrating several applications of the circuit breaker of FIG. l;

FIG. 8 is a fragmentary side elevational view of the 3 operating components in a circuit breaker according to anotherembdiment ofthis invention; and v FIG. 9 is a schematic view illustrating an application of the circuit breaker of FIG. 8.

Referring to the drawings in detail, and initially to FIG. 1 thereof, it will be seen that the invention is there shown embodied in a circuit breaker 10 having a case 11 of plastic insulating material formed in back and front sections 11a and 11b which are suitably secured together, as by screws (not shown). A fixed contact 12 is secured within case 11, as by connection to a terminal post 13 which extends through the wall of section 11a and is secured to the latter by a nut 14. A movable contact 15 for engagement with fixed contact 12 is formed as an end portion of a conducting lever or blade 16 which is pivotally mounted on a shiftable pin 17 seated in slotted ears 18 at the back end of a magnetically permeable frame 19. Lever or blade 16 is normally biassed in the clockwise direction, as viewed on FIG. 1, that is, in the drection for moving contact 15 away from fixed contact 12, by a torsion spring 20 having a bight engaging blade 16 and legs wound around a pin 21 and anchored beneath lugs 22 which project from the sides of frame 19. Such lugs 22 may be engaged in suitable grooves (not shown) in the side wall surfaces of case section 11a for locating and securing the frame 19 within the case.

Blade 16 is manually reciprocable to move contact 15 toward and away from fixed contact 12 by a handle 23 which is pivoted on a pin 24 carried by ears 25 at the front end of frame 19, and which is connected to blade 16 through a collapsible linkage, for example, in the form of a toggle mechanism 26, as shown. Toggle mechanism 26 is seen to include links 27 and 28 pivotally connected to each other by a pin 29. Link 27 is further pivotally connected by a pin to blade or lever 16, while link 28 is pivotally connected by a pin 31 to ears which project from handle 23.

In the circuit breaker of the type shown on the drawing, links 27 and 28 are provided with comple-mentary latching members consisting of a rockable shaft 32 carried by link 27 and a tooth 33 projecting from link 28 (FIG. 2). When tooth 33 engages the periphery of shaft 32, as shown on FIG. 2, links 27 and 28 are rigidly connected or locked relative to each other in an extended condition at which an ear 34 projecting from the top of link 27 engages the top edge of link 28. In such relatively extended condition of links 27 and 28, the axis of pin 29 connecting the two links is disposed above the line of force passing through the axes of pins 30 and 31 which connect toggle mechanism 26 with blade 16 and handle 23, as shown on FIG. l. Further, when lhandle 23 is pivoted to its ON or closed contact position for engaging contact 15 with fixed contact 12, as shown on FIG. l, the line yof force extending between the axes of pins 30 and 31 passes below the axis of pin 24 on which handle 23 is mounted so that the reaction to the force exerted on blade or lever 16 to fhold contact 15 engaged with contact 12 in opposition to the spring 20 tends to turn handle 23 in the counter-clockwise direction, as viewed, that is, in the direction for retaining the handle in its ON position at which the ends of pin 31 engage the top edges of ears 25.

It will also be apparent from the above described relationship af the axes of pins 29, 30 and 31 in the extended condition of links 27 and 28 that the force of spring 20, in tending to move contact 15 away from fixed contact 12, seeks to collapse links 27 and 28 by effecting upward movement of pin 29 connecting such links, as shown on FIG. 4. However, such collapsing of links 27 and 28 is prevented so long as the periphery of shaft 32 is engaged by tooth 33, as on FIG. 2. As shown, shaft 32 has a diametrically extending notch or recess 35 through which tooth 33 can move to permit relative collapsing of links 27 and 28 when shaft 32 is rocked or Cil Vtion (FIG. 1) to 4, turned in the clockwise direction ing position.

An arm 36 extends radially from one end of shaft 32 along a side of link 27 and has an inwardly directed extension 37 at its free end which is loosely received in notches 38 provided in the sides of link 27. A spring 39 (FIG. 2) acts on extension 37 to yieldably hold the latter against bottom surfaces of notches 38and thereby yieldably retain shaft 32 in its latching position. However, notches 38 provide sufiicient clearance for extension 37 to permit upward rocking of arm 36 to the extent necessary to turn shaft 32 to its released position where recess faces toward tooth 33 which is then movable through recess 35 for collapsing the links of toggle mechanism 26.

A relatively light torsion spring 40 (FIG. l) extends around pin 24 and has its opposite ends anchored against pin 31 and against an ear 25 of frame 19 so as to urge handle 23 in the clockwise direction, as viewed, to its OFF or open contact position indicated in broken lines at 23 on FIG. 4. However, the force exerted by spring 40 is insufficient `to overcome the previously described force tending to hold handle 23 in its ON position so long as links 27 and 28 are latched in their extended condition.

Tripping of circuit breaker 10 is effected by an actuating arm 41 which is pivoted on a pin 42 carried by ears 25 of frame 19, and which is movable from below against arm 36, when lever 16 is disposed to engage contacts 12 and 15, so as to rock shaft 32 to its released position. So long as actuating arm 41 is in its inoperative or depressed lposition shown on FIG. 1, such actuating arm is clear of arm 36, whereby shaft 32 remains in its latching position to lock links 27 and 28 in their relatively extended condition for either moving contact 15 against fixed contact 12 in response to displacement of handle 23 to its ON position or for retaining contact 15 in engagement with contact 12 and holding handle 23 in its ON position. However, when actuating arm 41 is rocked upwardly from the depressed position shown on FIG. 1 to the tripping or elevated position shown on FIG. 3, such actuating arm can act upwardly on arm 36 to rock shaft 32 to its released position and thereby collapse links 27 and 28 of the toggle mechanism, as shown on FIG. 4, to trip the circuit breaker, that is, to permit spring 20` to move contact 15 away from fixed contact 12 at a time when handle 23 is in its ON position. When toggle mechanism 26 has been collapsed, as on FIG. 4, spring 40 can then rock handle 23 from its ON position to its OFF position indicated in broken lines at 23', whereupon toggle mechanism 26 returns to its extended position with contact 15 spaced from contact 12. However, so long as actuating arm 41 remains in its tripping or elevated position of FIGS. 3 and 4, movement of handle 23 from its OFF position to its ON position will bring arm 36 against actuating arm 41 to collapse the toggle mechanism and thereby prevent continued engagement of Contact 15 with contact 12 in response to such movement of handle 23 from its OFF position to its ON position.

The structure of circuit breaker 10, so far as described above, generally corresponds to that previously employed in circuit breakers ex-tensively used for protecting against overload currents. In such known circuit breakers, actuating arm 41 is moved from its inoperative depressed posiits elevated tripping position (FIG. 3), where it acts upwardly against arm 36 and thereby trips the circuit breaker, only in response to the sensing of an overload current. However, in circuit breaker 10 in accordance with the present invention, actuating arm 41 is magnetically biassed Ito its elevated or tripping position (FIGS. 3 and 4) where it acts against arm 36 to trip the circuit breaker or to prevent closing of its contacts, and such magnetic bias is overcome to ldispose actuating arm 41 in its inoperative or depressed position (FIG. 1) only when the current flowing in an associated circuit, or the voltage impressed on such circuit, is above a predetermined minimum value.

from its illustrated latch- As shown, actuating arm 41 is magnetically biassed to its elevated or tripping position by a permanent magnet 43 which is carried by a depending extension 44 of arm 41, and which is polarized so that the poles thereof appear at the opposite faces of the magnet, thereby to produce a magnetic flux urging magnet 43 toward an iron or other magnetic core 45 of a solenoid coil 46 suitably supported by frame 19. It will be apparent that, when a direct current is passed through coil 46 in the direction to produce a magnetic flux opposing that of permanent magne-t 43, that is, tending to repel the permanent magnet from core 45, and the magnitude of such direct current is above a predetermined value, as determined by the strength of permanent magnet 43 and the ampere-turns of coil 46, magnet 43 is displaced away from core 45, as shown on FIG. l, to move arm 41 to its inoperative position and thereby permit closing of contacts 12 and 15 by -manipulation of handle 23.

In circuit breaker 10, terminals A and B for connection to a circuit to be controlled are constituted by the previously mentioned terminal screw 13 by which tixed contact 12 is secured in case 11 and by a terminal screw 47 which also extends through the back wall of case section 11a and is connec-ted to conducting blade 16 by way of a exible wire 48. Separate terminals C and D constituted by terminal screws 49 and 50 extending through the back wall of section 11a and being connected with the opposite ends of coil 46 by way of wires 51 and 52, are provided for connecting coil 46 to the circuit being monitored, which circuit may be the same as, or separate from the circuit controlled by contacts 12 and 15.

Referring now to FIG. 5, it will be seen that the above described circuit breaker may be employed to permit the completion, by its contacts 12 and 15, of one circuit, for example, a circuit for energizing a motor 53 which drives a conveyor through a tunnel oven, only when more than a predetermined minimum direct current, as established by the ampere-turns of coil 46, is owing in a circuit monitored by such coil, for example, a circuit containing a plurality of electrical resistance heating elements 54 for heating the tunnel oven through which the conveyor is driven by motor 53. In the example shown on FIG. 5, an open connection to any one of resistance heating elements 54, or any other failure in the monitored circuit, will reduce the direct current flowing through coil 46 below the value required for repelling permanent magnet 43 away from the core 45, whereby permanent magnet 43 will be attracted to the core to move actuating a-rm 41 of -the circuit breaker to its tripping position either to trip the circuit breaker, and thereby halt operation of motor 53, or to prevent closing of contacts 12 and 15 by manipulation of handle 23 for initiating operation of motor 53.

In the arrangement shown on FIG. 5, both the circuit controlled by contacts 12 and 15 and the circuit monitored by coil 46 are connected to a D.C. supply, s-o that, if desired, the terminals B and D can be replaced by a single terminal to which both movable contact and an end of coil 46 are connected. However, when two pairs of terminals A and B, and C and D are provided, the circuit controlled by the circuit breaker contacts may be connected to an A.C. supply and the D.C current to 4be monitored by coil 46 may be derived from a separate source, or, as shown on FIG. 6, it may be derived from a full-wave rectifier 55 having its input terminals connected to the A.C. supply and its output terminals connected in the circuit which is connected to terminals C and D of the circuit breaker lfor monitoring by coil 46. Further, as shown on FIG. 6, the monitored circuit may include a switch 56 disposed at a location remote from circuit breaker 10. So long as switch 56 remains in its normal closed position, the direct current flowing in coil 46 is intended t-o be sufficient to magnetically repel magnet 43 away from core 45 and thereby maintain actuating arm 41 in its inoperative position so that handle 23 can be manipulated to either close or open the circuit which includes contacts 12 and 15 and a suitable load 57. Whenever desired, for example, in the case lof an emergency, circuit breaker 10 can be tripped so as to disconnect load 57 from the A.C. supply by manually opening switch 56 at the location remote from circuit breaker 10. Such opening of switch 56 interrupts the current to coil 46, whereby permanent magnet 43 is attracted to core 45 to displace actuating arm 41 to its tripping position.

In each of the arrangements described above with reference to FIGS. 5 and 6, circuit breaker 10 has been em- .ployed t-o magnetically bias its actuating arm 41 to the tripping position thereof whenever the current in a monitored circuit is below a predetermined minimum value. However, as shown on FIG. 7, circuit breaker 10 may also be used to prevent the connection of a load 57 to a supply whenever the voltage impressed by the latter on the monitored circuit is below a predetermined value. In such arrangement, the cir-cuit to be controlled by contacts 12 and 15 may be connected to an A.C. supply, and the monitored circuit may derive DsC. voltage from a full wave rectifier 55 which is connected to the A.C. supply, with the monitored circuit including a resistor 58 in series `with coil 46. Thus, a decline -of the voltage at the A.C. source below a predetermined minimum value, or the a-bsence of voltage as such sour-ce, will reduce the current owing through coil 46 below the minimum value for repelling lpermanent magnet 43, and magnet 43 will be attracted to core 46 to dispose actuating arm 41 in its tripping position, thereby to trip the circuit breaker for disconnecting load 57 from the source or to prevent closing of contacts 12 and 15 for connecting the load to the source.

Referring now to FIG. 8, it will be seen that, in a circuit breaker 10a in accordance with another embodiment of this invention which is otherwise similar to the previously described circuit breaker 10 and has its corresponding 4parts identied by the same reference numerals, there is further provided a member 59 of iron or other magnetic material suitably fixed within the case at a location spaced from c-ore 45 so that permanent magnet 43 is movable between the position shown on FIG. 8, where it is magnetically attracted or latched to member 59 to dispose actuating arm 41 in its inoperative position and a position against core 45 to dispo-se actuating arm 41 in its tripping position.

As shown on FIG. 9, cir-cuit breaker 10a may be employed to permit or bar the selective closing and opening of contacts 12 and 15 by manipulation of handle 23, thereby to complete or interrupt, respectively, a circuit connected to terminals A and B, in response to the reception through a circ-uit connected to terminals C and D of oppositely directed D.C. pulses or signals. Thus, for example, if it is assumed that magnet 43 is initially attracted to core 45 to ydispose arm 41 in its tripping position and thereby bar closing of contacts 12 and 15, a direct current pulse or signal may be transmitted to coil 46 in the direction of the arrow 60 to produce a magnetic flux which repels permanent magnet 43 away from core 45 and against member 59 where i't is magnetically latched to retain actuating arm 41 in its inoperative position. Such pulse may signal that other circuits are in safe condition to permit closing of the circuit including contacts 1`2 and 15. Thereafter, arm 23 can be manipulated to either open or close contact 12 and 15. However, when a direct current pulse .of suflicient strength is received in the direction of the arrow 61, which pulse may indicate the occurrence of an unsafe condition, the `resulting magnetic ux produced -by coil 46 attracts magnet 43 away from member 59 and into contact with core 45 where it is thereafter magnetically latched or retained to hold actuating arm 41 in its tripping .position for either tripping circuit breaker 10a or preventing closing of its contacts 12 and 15 by manipulation of handle 23 to its ON position. Once permanent magnet 43 is thus moved into contact with core 45, it will be magnetically retained in that position until a pulse is again received in the direction of the arrow 60.

Although illustrative embodiments of the invention and various applications thereof have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments or applications, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as delined in the appended claims.

What is claimed is:

1. -In a circuit breaker having a handle connected to a movable contact by way of a collapsible linkage and being movable to engage said movable Contact with a iixed contact so long as said linkage is in :an extended condition, said movable contact being biased in the direction away from said iixed contact and movable in said biassed direction independently of said handle upon collapsing of said linkage, an an actuating member movable from an inoperative position to a tripping position where it is operable on said linkage to cause collapsing of the latter, the combination of a permanent magnet connected with said actuating member to move the latter, and a solenoid coil having a core, said magnet being polarized to be urged by its magnetic flux relative to said core in the direction for moving said actuating member to said tripping position, whereby said movable contact can be held in engagement with said fixed contact only upon the passage through said coil of a direct current capable of producing a magnetic flux of such magnitude and polarity as to overcome said magnetic flux of the permanent magnet.

Z. A circuit breaker according to claim 1, in which said collapsible linkage is in the form of a toggle mechanism having latching means to retain the toggle mechanism in said extended condition, said latching means being acted upon and thereby released by said actuating mem-ber when the latter is moved to said tripping position and said movable contact is engaged with said fixed contact.

3. A circuit breaker according to claim 1, in which said permanent magnet is urged by its said magnetic flux in the direction toward said core, whereby said actuating member is displaced to said inoperative position upon the passage of a direct current through said -coil lin the direction causing the resulting magnetic ilux to repel said magnet and of a magnitude exceeding a predetermined value dependent on the strength of said permanent magnet and the ampere-turns of said coil.

4. A circuit breaker according to claim 3; further comprising a member of magnetic material fixedly disposed to magnetically latch said permanent magnet at a position away from said core which corresponds to said inoperative position of said actuating member so that even a pulse of direct current through said coil in the direction to repel said magnet and of a magnitude exceeding said predetermined value causes said actuating member to remain in said inoperative position until at least a pulse of direct current is supplied to said coil in the direction to produce a magnetic flux attracting said magnet to said core with a force exceeding that of the magnetic attraction o'f said magnet for said member of magnetic material.

5. A circuit breaker according to claim 1, further comprising terminals respectively connected t0 said iixed and movable contacts and to the ends of said coil, so that said coil oan monitor `a circuit separate Ifrom that controlled by said contacts.

6. A circuit breaker according to claim 1, further comprising a resistance in series with said coil so that said movable contact can Ibe held in engagement with said fixed contact only when at least a predetermined voltage is impressed on a circuit including said resistance and coil.

7. A circuit breaker according to claim 1, further comprising rectifier means having output terminals connected with said coil and input terminals adapted for connection to an alternating current circuit to be monitored.

References Cited UNITED STATES PATENTS 2,632,072 3/1953 Zellner 335-78 2,912,544 11/1959 Piteo 335--20 2,938,980 5/1960 Iencks 335-20 BERNARD A. GILHEANY, Primary Examiner. H. BROOME, Assistant Examiner.

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