US3081387A

US3081387A - Circuit breaker

Info

Publication number: US3081387A
Application number: US77134A
Authority: US
Inventors: Benjamin H Smith
Original assignee: Heinemann Electric Co
Current assignee: Heinemann Electric Co
Priority date: 1960-12-20
Filing date: 1960-12-20
Publication date: 1963-03-12
Anticipated expiration: 1980-03-12

Description

March 1963 B. H. SMITH 3,081,387

CIRCUIT BREAKER Filed Dec. 20. 1960 5 Sheets-Sheet 1 B L IIw/I w: 1 L- 5 4 i 4 5 gr J I 7 /7' x /A'/7Z INVENTOR 3 82 85 4O BENJAMIN HSmTH H/S HZTORIUEY March 12, 1963 1 B. H. SMITH 3,081,387

' cmcurr BREAKER 7 Filed Dec. 20. 1960 3 Sheets-Sheet 3 INVENTOR. BENJAMIN H. 5mm

/s QTTORMEV United States Patent Ofilice 3,081,387 Patented Mar. 12, 1963 Filed Dec. 20, 1960, Ser. No. 77,134 14 Claims. (Cl. 200-103) This invention relates to electromagnetic circuit breakers having a solenoid coil and a retarded magnetically permeable core member for establishing a time delay, upon a predetermined energization of the solenoid coil, prior to the actuation of the electromagnetic mechanism. Particularly, this invention relates to a device for establishing a time delay period in a circuit breaker mechanism at excessive overload currents. It is an object of this invention to providean improved electromagnetic-device for establishing such a time delay period in a circuit breaker.

The type of electromagnetic circuit breakers to which this invention relates is illustrated by United States of America Patent No. 2,360,922 issued to K. W. Wilckens. In these circuit breakers, a linkage mechanism is actuated by an electromagnet for opening the contacts of the circuit breaker upon a predetermined current in the electromagnetic coil. The predetermined electric current in the coil moves a magnetically permeable core, against a biasing force and a retarding liquid, in the direction to close a gap in the magnetic circuit, whereby the electromagnetic flux becomes sufficient to move an armature in the direction to operate the circuit breaker mechanism for opening the contacts.

Certain prior circuit breakers have been constructed so that upon the occurrence of a momentary overload, below 1000% of rated current, the restraint on the core has prevented instantaneous movement of the core in the direction to close the gap in the magnetic circuit. But if the overload current below 1000% of rated current and above a minimum overload current of between 110 and 125% of rated current continues for a suflicient time period, the core is moved, by the abnormal flux, in the direction to close the gap. This so closes the magnetic circuit, after a time delay period, that the magnetic flux becomes sufiicient to move the armature in the direction necessary to operate the mechanism for opening the contacts. Heretofore, in these circuit breakers, upon the occurrence of a short circuit or excessive overload current, that is, a current exceeding 1000% of rated current, the armature has been instantly actuated by the excessive flux for opening the contacts.

For certain uses, however, it is desirable to provide a time delay between the occurrence of overload currents including those in excess of 1000% but below 4000% of rated current and the actuation of the mechanism, but to provide a device which will be instantly actuated at currents at or above the higher limit, that is, 4000% of overload current or more. It is an object of the present invention to provide a device that is adapted for obtaining time delay periods at such high overload current values and which is instantly actuated at very high overload currents.

It is a further object of the present invention to provide a time delay device for excessive overload currents which may be incorporated economically with known constructions of circuit breaker mechanisms.

Another object of the invention is to provide a magnetically operated device having a portion which may be readily disengaged from the apparatus, so that the circuit breaker is adaptable for two instantaneous overload current values at which the circuit breaker will be instantly opened, one of these values being very high compared to the other.

One embodiment of the invention is incorporated in an electromagnetic circuit breaker comprising an electromagnet including a coil and magnetically permeable frame members in the magnetic field of the coil. The permeable frame members are normally separated from one another by a gap which is automatically closed by a movable mag-.

netically permeable core upon sufficient energization of the coil to produce an electromagnet having adjacent poles of opposite polarity for attracting an armature. The core is biased to one end of a tube and the coil is mounted around a portion of the tube for moving the core, against its bias and the retarding action of the liquid Within the tube, to thereby reduce the gap and provide a time delay, as it is well known in the art. before the core moves to a position in which the gap in the magnetic circuit is closed sufiiciently for rotating the armature for overload current values below a predetermined value.

The armature is pivotally mounted on the frame and moves, upon sufficient energization of the coil, in the direction to trip the circuit breaker mechanism for opening the contacts thereof. Were it not for the present invention the armature would be attracted instantly to its associated pole upon an excessive current, such as 1000% of rated current, without an intervening time delay period between the initiation of the excessive overload current in the coil and the actuation of the armature. The present invention provides a device for preventing the foregoing and restraining the movement of the armature for a predetermined period of time (at such excessive overload currents below a very high overload current), the time delay period being determined by the movement of the core member in conjunction with a second core member and a movable magnetic device.

The magnetic device is spring biased away from the second core and toward the position in which it will restrain movement of the armature toward the solenoid coil. When the solenoid coil is energized by an excessive overload current, for instance, above 1000% but below 4000%, the first core moves against its restraint and subsequently also moves the second core against its restraint. After the lapse of a certain predetermined time period, depending on the value of the overload current, the first core has moved the second core sufliciently toward the movable magnetic device whereby the magnetic attraction between the magnetic device and the second core becomes suflicient to rotate the magnetic device and to move it out of restraining engagement with the armature, whereby the armature is allowed to move toward one pole of the solenoid coil. Movement of the armature actu ates the circuit breaker mechanism and th contacts open.

The foregoing and other objects of this invention, the principles of this invention, and the best mode in which I have contemplated applying such principles will more fully appear from the following description and accompanying drawings in illustration thereof.

In the drawings:

FIG. 1 is a side elevation view, partly in section, illustrating the invention incorporated in an electromagnetic circuit breaker, showing the closed position of the contacts;

FIG. 2 is a partial sectional view taken along the line 22 in FIG. 1;

FIG. 3 is a partial sectional view taken along the line 3-3 in FIG. '2, illustrating the time delay device in detail;

FIG. 4 is a partial sectional view illustrating the armature and armature restraining device in the position for restraining the armature;

FIG. 5 is a view similar to FIG. 4 but illustrating the positon of the device when the armature is not restrained and the coil has been energized sufficiently to fully actuate both cores; and

FIG. 6 is an exploded perspective view illustrating the armature, armature restraining magnetic device and associated supporting frames and pintles.

Referring to the drawings, the invention is incorporated in a circuit breaker comprising a casing formed by a base 21 and a cover 22 enclosing a stationary contact 23 anda movable contact 24 carried by a movable arm 26. The movable arm 26 is biased by a spring 27, mounted on the pintle 28, to the open position of the contacts' On predetermined overload currents the spring 27 actuates the arm 26 clockwise, there-by opening the

contacts

23 and 24, by carrying the arm 26 and the contact 24 toward the handle 30.

An automatically resettable mechanism '32 including a pivotal latch 33 is biased by a spring 31 to the latched position. When the mechanism 32 is latched it holds the contact 24 in engagement with the contact 23 (against the bias of the spring 27) but the mechanism 32 is trippable by an armature 34 during certain overload current conditions for opening the

contacts

23 and 24 of the circuit breaker. The armature 34 is pivotable about a pintle 35 and is biased by a spring 37 in the counterclockwise direet'iontFIG. 4) so that the arm 41 is biased away from the latch 33. Manual movement of the handle 30 to the right or left is transmitted by the mechanism 32 to actuate the movable arm 26 to the contacts open or the closed positions.

The overload currentsensing device comprises a magnetically permeable L-shaped frame 36 having vertical and horizontal legs. The frame 36 partially surrounds a solenoid coil 38 formed about a tube 39, the latter preferably of nonmagnetic material and electrically insulated from the coil 38, the frame 36 and the upper pole piece 40 by insulators 42, FIGS. 4 and 5. The coil 38 is connected by a flexible conductor 47 to the movable arm 26 and at the other end to a terminal structure 48, the stationary contact 23 being connected to a terminal structure 49. Upon predetermined overloads the coil 38 actuates the armature 34 to rotate the arm 41 into engagement with the latch 33 for tripping the mechanism 32 whereupon the

contacts

23 and 24 open, the handle 30 moves to the off position and the mechanism 32 automatically resets due to the bias of the spring 46. As illustrated, the frame 36 is provided with two dependingintegral ears 43, spaced from each other and together forming with the horizontal portion of the frame 36 a channel shape, the tube 39 extending through the horizontal leg of frame 36. The movable arm 26 pivots about a pintle within the tube 63 is a second'core 64 of magnetically permeable material biased, by a compression spring 66, toward the pole piece 48. The second core 64 is in abutment with the upper face (PEG. 4) of the pole piece 40 when the contacts of the circuit breaker are in the closed position and the coil is energized below a predetermined current value or thecontacts are open. The spring 66 is retained in proper position by an annular upstanding edge portion 67 of the core 64. Disposed within the tubes 39 and 69, including the opening 58, is a suitable liquid to provide'a dash pot action against the movement of the

cores

50 and 64.

Associated with the second core 64 is a magnetic device 68 for'restraining movement of the armature 34 below 44 having ends received in elongated bushings 55 formed in the ears 43, the arm 26 being disposed between the spaced ears 43. Also, the ends of the pintle 28 are carried by the ears 43.

Disposed within the tube 39 is a first core member which is biased toward the lower end of the tube 39 by a compression spring 52 and extending through the horizontal leg for the frame 36, FIGS. 4 and 5. The core 50 comprises a forward cylindrical body portion 45, of magnetically permeable material, having a rear portion 51 of larger diameter defining an annular shoulder 54 engaged by one end of the spring 52, the latter having another end abutting the pole piece 46. The core'50' includes a forward cylindrical nose portion 56 of smaller 45. The nose portion 56 is movable into and through an opening 58 in the pole piece 48 to engage the second core 64. The nose portion '56 is preferably formed of non- -magnetic material such as brass and is small in length compared to the length of the

portions

45 and 51.

- cross sectional diameter than the forward 'body portion a predetermined excessive overload current. The magnetic device 68 comprises a permanent magnet 70 supported by a hanger 72 having fingers 73 frictionally engaging thernagnet 70. The magnet 78 is spaced from the cap 62, when in the contacts closed position and the .coil is energized below a predetermined value or the contacts are open, but is generally aligned with the longitudinal axis of the tubes-39 and 66. The magnet 70 has about the same diameter as. the second core 64 but is larger than the core 50. The hanger 72 is pivoted by bearings formed in ears 71 and through which extends the ends of a pintle 74 into openings in a frame 76, the frame 76 being secured to and projecting from the frame 36. The hanger 72 includes a detent or finger 78 extending below the pintle 74 and the magnet 70 for restrainably engaging the lower surface of the generally horizontal portion 80 of the armature 34 during excessive overload currents below a predetermined very high overload current, or for a time delay period for overload currents below this predetermined very high overload current.

The generally horizontal portion 80 of the armature '34, as illustrated in FIG. 4, includes an opening 82,

through which the finger 78 extends, and a yoke 84. The yoke 84, almost completely surroundsthe cap 62 when the yoke 84 is attractedby the coil to the position illustrated in FIG. 5. The opening 82 is large enough to allow relative movement between the armature 34 and the magnetic device 68'by being longer and wider than the finger 78 so as to allow the lateral projection 77 to freely enter the opening 82 when the magnetic device is rotated clockwise (by the magnetic flux) to free the yoke 84. When the yoke 84 is thus released, the lateral projection 77 becomes disposed within the opening 82 but spaced from the walls defining the opening 82, FIGS. 2 and 5, and the armature 34 rotates toward the pole piece 40, until it abuts the pole piece 40, FIG. 5, due to the magnetic flux.

The pintle 74 is restrained, at one end by a spring 79, having its ends crossed and secured in a suitable notch in the frame 76 and there is wrapped around the pintle 74 a torsionspring 81. The spring 8-1 has one end engaging the slanted bridging portion 85 of the hanger 72 and the other end disposed within a slot 83 for biasing the hanger 72 in the counterclockwise direction (FIG. 4)

about the pintle 74 and away from the second core 64. Since the armature 34 is likewise biased by its spring 37 in the counterclockwisedirection and the projection 77 of the finger 78 is shaped to engage and hold the lower surface of the yoke 84, movementof the yoke 84 toward the pole piece 40 is restrained until the magnetic device 68 pivots sufficiently toward the pole piece 40 to disengage the projection 77 from the yoke 84 by moving the latter projection 77 to the left.

As illustrated in the drawings, the core 64 is constructed to have a larger cross sectional area, in a plane gen erally parallel to the plane of engagement between the cap 62 and the permanent magnet 76}, than the core 50. The length of the core 64 is, however, relatively small compared to the length of the core 50. Also, the frame 76may be provided with a projection 89 for limiting movement of the armature in the counterclockwise direction, if desired. Also, the spring 66 is relatively weak compared to the spring 52.

. With the device constructed as illustrated, at overload currents above a minimum value but below a first predetermined very high value, for instance, between 110% and 4000% of rated current, respectively, the magnetic device 68 restrains the movement of the armature 34. The core 50 is moved upwardly against the bias of spring 52 and the dash pot action of the liquid by the magnetic fiuX. After a time delay period, the core 50 engages and moves the second core 64 upwardly, against the latters spring bias and the dash pot action of the liquid, to a position where the magnetic attraction between the permanent magnet 70 and the magnetically permeable core 64 becomes sufiicient to overcome the spring bias on the magnetic device 68 and rotates the latter in the clockwise direction, moving the projection 77 out of restraining engagement with the yoke 84, whereuponthe yoke 84 is allowed to. movetoward the pole piece due to the magnetic fiux,and the armature 34 pivots and unlatches the mechanism 32.by engagement of the arm 41 with'the pivotal latch133;:-..The"yoke 84 maybe moved into contact witlrfthe'pole :piece"40 (FIG..5') and if the vertical leg of frame .36 islongienough; intocontact with frame 36 also; but'is not so illustrated.

At very high overload'currents above this first predetermined value, for instance, above 4000% of rated current, the magnetic fluX created by the solenoid coil 38 is sufiicient to attract and pivot simultaneously and instantaneously both the permanent magnet 70 and the yoke 84 of the armature 34 for tripping the mechanism 32.

If it is desired to trip the circuit breaker mechanism instantly upon the occurrence of a second predetermined excessive current value-below the aforementioned first very high value, for instance, 1000% of rated current,

the lateral projection 77 of finger 78 may be bent to the left (FIG. 4) out of restraining engagement with the yoke 84. In such event, the magnetic device 68 will become independent of the armature 34 and have no effect thereon. For overload currents below this second'predetermined value, but above a predetermined minimum value, for instance, the aforesaid 110% of rated current, time delay periods will exist due to the restraint of the spring 52 and the dash pot action of the liquid within the tubes '39 and 60. In such event, at overload current values abovethis second value (1000% of rated current), the magnetic fields produced by the coil will be sufficient to cause the instantaneous pivoting of the armature .34, whereby the armature arm 41 engages the mechanism 32 to open the contacts of the circuit breaker.

When the magnetic flux is sufiicient to pivot the armature 34 and the magnetic device 68 toward the position illustrated in FIG. 5, "the arm 41 pivots the latch 33 to open the contacts. The coil 38 thenbecomes de-energized and-the armature 34 rotates in a counterclockwise direction due to its spring bias as, also, does the magnetic device; 68,- after-the core 64 retracts sufficiently. Since the armature 34 and the device'68are both biased'in the counterclockwise direction, the finger 78 slips into engagement with the lower surface of the yoke 84 during such counterclockwise movement, returning to the position illustrated in FIG. 4.

The armature may be provided with an integral balance arm 91, if desired. Counterclockwise movement of the armature 34 may be limited by abutment of a portion of the leg 41 with the vertical leg of the frame 36, as illustrated in FIG. 4. Preferably, the upper portion of the hanger 72 is spaced from the adjacent casing wall to facilitate movement of the hanger 72. Movement of the

cores

50 and 64 may be simultaneously limited by abutment of the forward portion with the pole piece 40 and the abutment of the second core 64 with the cap 62 when the-magnetic flux causes movement of the cores and 64.

From the foregoing it is seen that when the finger 78 ha is positioned to restrainably engage the yoke 84, a time delay unit has been provided which includes two time delay devices providing two cumulative time delay periods adapted for use with certain current conditions.

Having described this invention, I claim:

1. An electromagnetic structure comprising an armature, an electromagnet in operative association with said armature, said electromagnet including a coil and a magnetizable frame in the magnetic field of said coil, a two'- piece magnetizable core, one of said two pieces of said core being moved by the coil for moving the second core piece, and magnetic means releasable after sufiicient movement of the second core piece for restraining said armature prior to said movement.

2. An electromagnetic structure comprising an armature, an electromagnet in operative association with said armature, said electromagnet including a coil and a magnetizable frame'in the magnetic field of said coil, said .armature being actuated by said coil, first time delay means actuated by said coil for producing time delays below a predetermined current in said coil before actuation of said armature, and second time delay means controlled by saidfirst time delay means for preventing instantaneous movement of the'armature at current values above said first predetermined current and below the value of a second predetermined current and producing time delays below said second predetermined current and above the value of said first current, said first and second time delay means including sequentially movable cores biased toward the same end of the coil, and said second time delay means including a permanent magnet attractable by said second core when the latter is moved by said first core toward said permanent magnet.

3. In an electromagnetic circuit breaker comprising a solenoid coil, a frame supporting said solenoid coil, an

armature actuated by said coil from a first position to a second position, said coil including first and second magnetizable cores movable from first positions to second positions, said second magnetizable core being movable by said first core, and magnetic means attractable by said second core when said second core moves toward said second position, said magnetic means including an arm for restraining said armature when said armature is inv the first-position, and said arm maintaining said armature in the first position until the magnetic means moves toward the second core.

4. In an electromagnetic circuit breaker comprising a solenoid coil, a frame supporting said solenoid coil, an armature actuated by said coil from a first position to a second position, said coil including a magnetizable core movable from a first position to a second position, a second magnetizable core movable by said first core when saidfirst core moves toward said second position, and magnetic means attractable by said second core when said second core moves toward said second position, said magnetic means including an arm for restraining said armature when said armature moves toward said first position, said magnetic means being biased so that said arm tends to restrain said armature, and said arm maintaining said armature in said first position until said second core moves toward said second position sufficiently for the magnetic force between said magnetic means and said second core is large enough to overcome the bias on said magnetic means.

5. In apparatus of the character described an electromagnetic solenoid coil, a tube enclosed by said coil, a magnetically permeable core within said tube, means for retarding the movement of said core, an armature attractable by said core when said core moves to one end of said tube, means for [restraining movement of said armature, said last mentioned means including a magnetic device and a magnetically permeable device movable into proximity with each other by said core member when the latter moves toward one end of said tube, one of the two last mentioned devices having a portion engaging said 7 armature for restraining movement of said armature, movement of said devices into proximity with each other increasing the magnetic force of attraction between the two sufiiciently to actuate the device which moves the armature out of restraining engagement thereby allowing said armature to move.

6. An electromagnetic circuit breaker including relatively movable contacts, a mechanism for controlling said contacts, an electromagnetic overload sensing device, said mechanism being actuated by said overload sensing device, said overload sensing device including a solenoid coil and an armature, a time delay device for actuating said armature into tripping engagement with said mechanism after a time delay period for overloads below a predetermined current rating, said time delay device comprising first time delay means and second time delay means, said first and second time delay means including sequentially movable portions of magneti-z'able material actuated by the magnetic fluX field of said coil, saidfirst time delay means actuating said second time delay means, magnetic means associated with said second time delay means for releasing said armature at the end of the sec nd time delay period whereupon said armature actuates said mechanism for opening'the contacts.

7. An electromagnetic circuit breaker including stationary' and movable contacts, a linkage mechanism for moving the movable contact, an electromagnetic coil and armature, a first time delay means, a second time'd'ela'y means associated with said first time delay means, said second time delay means including a pivotal permanent magnet, a pole piece for said coil, said armature having a yoke around said magnet in one position, said second time delay means having a finger for restraining movement of said yoke, said second time delay means including a movable core, said core, yoke and permanent magnet being core pieces, said core pieces being all biased toward the same end of the tube, one of said core pieces being driven by a driver core piece upon suitable energization of the coil, said core pieces being movable against their biases, said driven core piece having a portion spaced from a portion of the driver core piece whereby a timedelay takes place upon movement of one before movement of the other core piece starts, relatively movable contacts, and a magnetizable mechanism'for controlling said contacts, said mechanism being controllable by the position of the driven core piecefor controlling said contacts.

9. The structure recited in claim 8 wherein said mag netizable mechanism comprises plural pivotal armatures movable relative to' each other, said armatures being both biased in the same direction, one of saidarmatures being a controlling armature and another a controlled armature, said controlling armature being actuatable against its bias by the magnetic attraction between itself and the driven piece toward said controlling armature during predetermined energization values of said coil to provide a time delay before actuation of the contacts, and said controlled armature being actuatable instantly at other predetermined energization values of said coil above said first mentioned energization values to provide-instantaneous actuation of the contacts at these energization values.

10. An electromagnetic structure comprising an electromagnet including a coil and a magnetizable frame in the magnetic field of said coil, two spaced magnetizable core pieces, said core pieces being both biased toward the same end of the coil, one of said two pieces driving the other piece upon suitable energization of the coil after a time delay period, said core pieces being movable against-their biases, relatively movable contacts, and a mechanism for controlling said contacts, said mechanism including. a

magnet-izable device controllable by the position of the driven cor'e piece for controlling said contacts.

11. The structure recited in claim 10 wherein said magnetizable device comprises first and second pivotal armatures movable relative to each other and biased in the same direction, said first armature having a portion for controlling movement of said second armature, said con-' trolling portion being actuatable against its bias by the and second armatures are disposed in interfitting relation with each other.

13. The structure recited in claim 11 in which as be-:

tween said driven core piece and said first armature one is a permanent magnet, said portion of said first armature restrains movement of said second armature during predetermined current coil values until said driven core moves sufficiently" close to said first armature to attract and pivot said first armature sufliciently to release the second arrnature to provide a time delay before actuation of the contacts due to pivoting of the second armature under in-' fiuence of the electromagnetic flux of the coil.

14. The structure recited in claim 13 wherein said armatures are jointly pivotally movable upon energization of the electromagnetic coil above a second higher predetermined coil current value.

References Cited in the file of this patent UNITED STATES PATENTS 2,072,932 Wilckens Mar. 9, 1937 2,451,962 Lindstrom Oct. 19, 1948 2,690,528 Wilckens Sept. 28', 1954 2,700,711 Wilckens Jan. 25, 1955 2,709,731 MacNeil May 31, 1955 2,756,302 Baltuch July 24, 1956 2,878,338 Gribble Mar. 17-, 1959 2,898,420 Kuze Aug. 4, 1959 w. WW

Claims

1. AN ELECTROMAGNETIC STRUCTURE COMPRISING AN ARMATURE, AN ELECTROMAGNET IN OPERATIVE ASSOCIATION WITH SAID ARMATURE, SAID ELECTROMAGNET INCLUDING A COIL AND A MAGNETIZABLE FRAME IN THE MAGNETIC FIELD OF SAID COIL, A TWOPIECE MAGNETIZABLE CORE, ONE OF SAID TWO PIECES OF SAID CORE BEING MOVED BY THE COIL FOR MOVING THE SECOND CORE PIECE, AND MAGNETIC MEANS RELEASABLE AFTER SUFFICIENT MOVEMENT OF THE SECOND CORE PIECE FOR RESTRAINING SAID ARMATURE PRIOR TO SAID MOVEMENT.