US2709730A

US2709730A - Circuit breaker

Info

Publication number: US2709730A
Application number: US237128A
Authority: US
Inventors: Albert B Rypinski
Original assignee: Murray Manufacturing Corp
Current assignee: Murray Manufacturing Corp
Priority date: 1951-07-17
Filing date: 1951-07-17
Publication date: 1955-05-31
Anticipated expiration: 1972-05-31

Description

A. B. RYPINSKI CIRCUIT BREAKER May 31, 1955 A5 sheets-511.861 1 Filed July l', 1551 nnentor Cttorneg May 31, 1955' A. E. RYPlNsKl 2,709,730 CIRCUIT BREAKER Filed July 17, 1951 @W6 49 Z/ l 5 Sheets-Sheet 2 nuentor aye gri/W nited States Patent fliee 2,709,730 Patented May 31, 1955 CIRCUIT BREAKER Albert B. lypinski, New York, N. Y., assignor to Murray Manufacturing Corporation, Brooklyn, N. Y., a corA poration of New York Application July 17, 1951, Serial No. 237,128 12 Claims. (Cl. 200-106) The invention herein disclosed relates to an electrical circuit breaker of nominal rated capacity such, for example, as is used in otiices and homes.

For some time, it has been generally recognized that circuit breakers of the kind to which this invention relates are desirable adjuncts for protecting electrical equipment and circuits from the destructive effects of continued overload and short circuits. As used in offices and homes and in conjunction with apparatus of nominal rated capacity, they provide desirable protection, and unlike fuses that are commonly used, need not be replaced upon automatically breaking the circuit. Also, unlike fuses, the occupant of the dwelling or office does not hesitate to reset a circuit breaker, whereas, in gen eral, fuses are inconveniently located and surrounded by exposed wiring which deters the uninitiated from attempting to locate and replace a blown fuse. However, heretofore and prior to the invention herein disclosed, circuit breakers of the kind mentioned have not come into common use because of the relatively high cost of reliable circuit breakers in this category.

An object of the invention herein disclosed is to provide a reliable circuit breaker of the kind mentioned having a simple operating mechanism so arranged and constructed that the circuit breaker is comparatively inexpensive to manufacture. Another object of the invention is to provide such a circuit breaker in which fewer parts are required than the number used in comparable, like circuit breakers. A further object of the invention is to provide a circuit breaker of the kind mentioned in which there are a minimum of corrosive parts. An additional object of the invention is to provide a fully magnetic circuit breaker of the kind mentioned.

The drawings include:

Figs. l, 2 and 3 which are, respectively, a side elevation, end elevation and top plan view of a circuit breaker embodying this invention;

Fig. 4 which is an enlarged, side elevation similar to Fig. l with part of the case removed;

Fig. 5 which is an enlarged, sectional, side elevation taken on the line 5-5 of Fig. 2;

Fig. 6 which is a sectional, transverse, elevation taken on the line 6 6 of Fig. 4;

Fig. 7 which is a side elevation, opposite to that of Fig. 4, with half of the case removed;

Fig. 8 which is a transverse, sectional elevation taken on the line 3-8 of Fig. 4;

Fig. 9 which is a fragmentary side elevation similar to Fig. 7 and showing the contacts in engagement;

Fig. l0 which is an isometric view of a spring element forming a part of the circuit breaker;

Fig. 1l which is an enlarged, fragmentary, transverse, sectional elevation through the magnetic coil and core, showing the position of the core elements during normal circuit conditions the section being taken on the line lit-1l of Fig. 9;

Fig. l2 which is a View similar to Fig. 1l showing the position of the core elements upon abnormally high current conditions; and

CTL

Fig. 13 which is an isometric view of half of a housing showing a modified form of connectors.

Circuit breakers of the kind to which this invention relates are, in general, classified as thermal, thermal magnetic, and fully magnetic. The thermal breaker releases due to the heating of an element, such, for example, as a bimetallic element, upon the passage of an abnormally heavy current therethrough. It is obvious, of course, that the ambient temperature will aff-ect the operation of such a breaker. Likewise, since the thermalmagnetic circuit breaker depends, in part, upon the heat ing of an element to effect the operation thereof, thisy type of breaker is affected by changes in the ambient temperatures at its position. A fully magnetic circuit breaker is not so affected as its operation depends solely upon the magnetism produced by the current passing therethrough.

The circuit breaker illustrated in the drawing, and which constitutes but one specific embodiment of the invention, is a fully magnetic circuit breaker, i. e. the automatic operation thereof is etected solely by the rise in current and electromagnetism produced in an electro` magnetic coil. ln general, the illustrated embodiment of the invention includes a case, designated generally by the character A; a stationary contact B within the case,

positioned to cooperate with a movable contact C; and operating mechanism within the case for electing engagement and disengagement (manually and automatically) of the stationary and movable contacts B and C respectively.

The operating mechanism includes a movable link train consisting of three links, a first link, an intermediate link and a third link, The first and intermediate links form an overcenter toggle and the intermediateand third links form an undercenter toggle. In the embodiment illustrated, the irst link D constitutes a piv otally mounted, manually operative handle; the intermediate link E constitutes a latch-link pivotally con nected to the handle; and the third link F is the main link that is slidably and pivotally mounted in the case and pivotally connected to the intermediate link E. A combined armature and lock, or lock-armature G, pivoted on the main link F, releasably engages the latch-link E and holds the operating mechanism in the position in which the contacts B and C are engaged. Carried by the main link F, there is an electromagnetic coil H which under certain conditions attracts the lock-armature G and releases the latch-link E so that the undercenter toggle collapses under the action of resilient means I. The lock-armature G, is biased toward locking position by a spring l.

By moving the handle D, the operating mechanism may be set or collapsed to close or open the circuit. When the operating mechanism is set, and the coil H attracts the lock-armature G, the lock is released from the latch-link E, the operating mechanism collapses under the action of the resilient means l, and the movable contact C moves away from the stationary Contact B to open the circuit.

The case A which forms a box-like structure, desirably, consists of two, complementary, longitudinally divided sections l and Each of the two halves, 1 and 2 of the cases A, preferably consists of a single piece of' molded, thermo-plastic or thermo-setting material which, when molded, is non-conductive, non-corrosive and rigid.` In the assembled structure, the two parts of the case, l and 2, are held together by three screws or rivets 3.. The assembled case has a boss 4 extending from the rear wall thereof. The boss 4 has an opening 5 there. through, through which two, flexible, stranded, insulated conductors or leads 6 and 7 extend.

in the assembled case, the inner surface of the rear wall S and the front wall 9 are shaped as shown, in part conforming to the shape of parts of the operating mechanism in its oli and on positions, and in part acting as stops for the operating mechanism; On the inner surface of the side wall it), forming a section of the part l of the case, there is formed a cylindrical depression lili adjacent the handle end of the circuit breaker. Also, formed in the inner surface of the side wall lil, there is an elongated slot i2 that is inclined with respect to the major dimension of the side wall. rl`his slot I2 is adjacent the opposite end of the case from the position ot the cylindrical depression il. A like cylindrical depression 13 and an elongated depression llt-l is formed in the inner surface of the side wall i5 that forms a section ot the part 2 of the case. In the assembled case, the cylindrical depressions 11 and i3 are axially aligned and the elongated depressions ft2 and ift are aligned. A slot i7, formed in the rear wall 8 of the case, receives a portion of the stationary contact B and positions the contact within the casing.

The handle D of the operating mechanism desirably consists of a single piece of molded, insulating material. It includes a nger piece that consists of an elongated (rectangular in cross section) neck it that extends through an opening I9 in the top wall Ztl of the casing, and an end, partially cylindrical portion 2i by means of which the handle may be manipulated. The handle D is provided with outwardly, oppositely extending, bearing or

pivot pins

22 and 23 that are received in the cylindrical depression l1 and 13 in the side walls itl and i5, respectively, of the case. In this manner, the handle is pivotally mounted in the case. On the opposite side of the pivotal axis of the handle from which the linger piece extends, the handle is provided with a relatively narrow side arm or extension 24 having a cylindrical opening 25 therethrough. On each side of the handle, concentric with the axis of the

pins

22 and 23, there are

grooves

26 and 27, respectively, which receive loops of the springs i that extend around the

pins

22 and 23.

The latch-link E is desirably molded as a single unit from some non-corrosive material-heat treated, hardened, non-shatterable glass, for example, although it may be made of metal or plastic. At each end of the link, there are laterally extending

pivots

28 and 29. The pivot 28 is received in the opening 25 formed in the extension 24 of the handle D. Intermediate the ends of the link, there is a latch extension 30 having a straight edge or face 3l which cooperates with the lock-armature G. The pivot 29 of the latch-link E, is received in an opening 32 which extends through an extension 33 formed on the main-link F.

Like the other parts of the link train, the main-link F is desirably molded as a unit from insulating material. it has a cylindrical portion 3a from which the extension 33 projects. The extension 33 is relatively narrow approximately the same thickness as the side arm 2li extending from the handle. At the side of the extension 53 there is a shoulder 3d which is positioned to engage the edge 35 of the latch-link E and acts as a stop. The cylindrical portion 34; has an axial opening therethrough, through which a core designated generally by the numeral 36 extends.

The coil H may be, and desirably is, molded in place in the main-link. It surrounds the axial opening through which the core 36 extends. In its simplest form, this winding or coil consists of a stranded conductor with insulation on each strand, so that the strands of the coil are insulated from each other. In the embodiment illustrated, one end of the coil extends from the side of the main-link F. This end of the conductor is long enough to extend through the opening through the boss 4. A sleeve of insulating material is slipped over this conductor and it becomes the lead wire extending out through the case. By using a stranded wire for the coil, it becomes unnecessary to solder, braze or weld a stranded conductor to the coil to take care of its movement in normal operation of the breaker. Thus, with a single cable, there is served three functions of a winding, a pigtail and a lead wire and it is unnecessary to braze or weld 5 two joints as in comparable constructions.

he other end of the coil extends through a boss 37 formed on the cylindrical portion 34 of the main-link F and is connected to the movable Contact C, which, in the construction shown, consists of a cup-shaped contact iff embracing the end of the boss 37. The movable contact is thus atlixed to the main-link and moves with the main-link. As will be observed, the contact C is located on one side of the lengthwise axis of the breaker and the axis of the link train slopes towards the opposite side l5 oi the case.

The core, in the embodiment of the invention illustrated in the drawings, consists of a glass tube 3% that extends through the axial opening in the cylindrical portion 34- of the main-link F. The tube extends beyond :ifi the side edges of the main-link and on each end thereof, there is a cup-shaped, end closure, closures lli and 41, which may be of brass, plastic or other material, and cemented in place on the end of the tube. Within the tube 39, there are two, movable cup-shaped, steel core if:

pieces

42 and 43, resiliently urged toward the end closures 4@ and di. respectively, by a spring 44. Desirably, the tube 39 is filled with oil.

The cup-shaped end closures dit and 41 extend beyond the side edges of the main-link F and into the inclined Si? slots i2 and 1d, respectively, formed in the side walls it? and i5. The main-link F is thus slidably and pivotally mounted in the case.

As previously stated, the resilient means I consists of a single piece of spring wire. It includes loops i5 and 35 le which receive opposite ends of the tube 39;

helical spring portions

47 and 48 that extend along opposite sides of the link train;

loops

49 and 50 which receive the pivot pins 22 and 23 of the handle; and a connecting, transverse portion 51 between the loops i9 and 50 that enits gages the handle. It will be observed that the loops 49 and 5i) each consists of several turns and constitute a coiled spring that biases the portion Si engaging the handle. With this arrangement, the helical spring portions 47 and i8 serve to bias the link train to the col- 5 lapsed position, open circuit position, and the portion Si, due to the

loops

49 and 50 independently biases the handle D toward the off position.

Under normal conditions, the link train is, when moved to the on position, maintained in such position against the action of the resilient means I, by the lock-armature G. This is formed as a single piece of steel, desirably a chromium plated or stainless steel stamping. it is shaped as illustrated and includes side arms S2 and S3 that ernbrace the main link It", a. transverse connecting portion 55 5d, and a locking tang 5S extending from the transverse portion 54, The arms S2 and 53 have openings therein that receive pivot pins 56 and 57 extending from opposite sides of the main link F. The lock-armature is thus pivotally mounted on the main link. As will be noted,

60 the

arms

52 and 53 have cut-away portions at the core tube for clearance and the transverse portion Effi is of substantial width, partially cylindrical and adjacent the under side of the cylindrical portion 3d of the main-link F, i. e. within the magnetic iield of the coil H. The locking tang 55 includes a curved portion 53 and an end section 59, the edge of which is positioned to engage, under normal conditions, the straight edge or face 3l of the latch extension 3i) on the latch-link E.

The lock-armature G is biased toward the position in which the edge of the end section 59 engages the face 3l. of latch-link E by the spring I. This spring consists of a single piece of spring wire coiled around the pivot 57 on the main-link F and having one end 6i? engaged in one of several grooves e1 formed in the side of the main-link F,

and an arm 62 engaging the transverse portion 54 of the lock-armature G. In assembling the circuit breaker the end titi of the spring I is inserted in one or the other of the grooves 6l to predetermine the tension of the spring I, and therefore the magnetic force required to attract the lock-armature and so release the latch-link E. The lockarmature engages a stop pin 52 mounted on one side of the main link F, to limit the movement of the lock-armature away from the core under the urge of the spring I.

The stationary or line terminal contact B desirably consists of a single piece of metal, preferably of copper or brass. It is preformed, in the embodiment illustrated, with a portion d3 that constitutes the contact; a spring portion till to maintain contact pressure; a portion 65 engaged in the groove or slot 17 in the wall of the housing and locating and supporting the unit: and a connecting portion 66 to which a lead wire 67 is secured as by welding or brazing. The contact is thus a flexible unit that can deflect at its lower end where the movable contact C engages it.

The circuit breaker may, as illustrated in Fig. 13 have different terminals. In this illustration, one end of the coil may be connected to a iixed terminal 68 either by being grazed or crimped in a hollow portion 69 thereof. The terminal 68 is positioned in slots in the case and has a terminal screw 79 outside the case. Also, the line terminal may be provided with a clip 71 for engaging a busbar when the circuit breaker is used in a panelboard.

As previously stated, the contact C is located to one side of the lengthwise axis of the circuit breaker and the axis of the link train slopes toward the opposite side of the case. This arrangement provides clearance in the upper part of the case for the link train to collapse, and in the lower part, on the opposite side, for the lock-armature to move away from the coil. The mechanism, therefore, occupies a minimum of space.

The operation of the circuit breaker is as follows: The handle D may be manipulated manually to open and close the breaker as is customary. This is effected by actuation of the over center toggle formed by handle D with the main link F and latch-link E. In such actuation the latch-link E remains in engagement with the lock-armature G.

T he latch-link E and the main link F form an under center toggle that is prevented from reaching center by engagement of the edge 35 of the latch-link E with the shoulder 34 of the main-link F. When a continued overload occurs, the

core pieces

42 and 43 move to the center of the core tube, due to the increase in magnetism in the coil H, the movement of the core pieces providing the desirable time delay, the lock-armature G is attracted to the coil and the latch-link E is released. The under center toggle then collapses under the action of the sections t7 and f-i of the spring I, and the handle is moved to the off position under the action of the section 51. The movable contact C moves with the main-link away from the stationary contact. On short circuit, the magnetism, of course is very great and the lock-armature releases the latch link E whether the core moves or not. When the circuit is broken, the spring J returns the lock-armature to its latching position and as the handle moves to off position it straightens out the link train until the lockarmature again engages the latch-link. This occurs just before the handle reaches off position. Moving the handle to the on position resets the breaker.

A magnetic blowout is a long recognized means for moving an intense electric arc from its point of origin to some position, where it can be lengthened out or otherwise suppressed. These usually take the form of a few series turns adjacent the arcing point.

In the breaker of this invention, the entire coil, of relatively many turns, is located just above the arcing point. Under short circuit conditions, where currents may be one hundred times normal or more, there is a very powerful magnetic field surrounding the coil. Due to CII d the many turns, this is several times as powerful as those usually employed, and correspondingly effective.

Inherent in the design described is the fact that the main-link F is relatively heavy and large. Its inertia is correspondingly great and its movement relatively slow. This fact is utilized, in the illustrated embodiment of the invention, to help in arc suppression on heavy currents. Sixty cycle alternating current, constituting almost the only kind on which this circuit breaker will be employed, reaches zero every one one-hundred-twentieth second. A good circuit breaker will ordinarily extinguish the short circuit arc in one-half of a cycle, or one one-hundredtwentieth of a second. With the arrangement disclosed, the inertia of the main-link F may be such as to separate the contacts approximately twenty-five thousandths of an inch in no less than one-half cycle and on further movement increase the break to substantially more than twenty-five thousandths of an inch.

The breaker herein disclosed opens with a combined rocking and sliding motion of the main-link F and movable contact C. It is well known that if relatively heavy contacts are employed and moved apart about one millimeter, a heavy alternating current can be interrupted in one half of a cycle, due to the quenching action of the heavy contacts, the small gap and the fact that the current goes to zero. This is too small a gap to be safe after the arc is out, since burnt particles of metal may fall in and close it. But once the arc is out the gap can be increased indefinitely with no bad effects. Due to the particular design of the breaker disclosed, the magnetic blowout and the above described arc suppression means are combined.

In opening contacts under heavy currents beads may form and subsequent closings may cause a slight projection weld, delaying the opening or holding the parts together. In the breaker disclosed, the rocking, sliding action of the contact C tends to break such a weld with large leverage, comparable to the action of n crowbar.

The ability to make the link train of non-metallic parts is important. Circuit breakers have to bc in condition to function instantly after many years of activity or inactivity. Most metals rust, oxidize or chance chemically in various atmospheres such as salt air, sulphur, ammonia fumes, or moist air under alternate heating and cooling. By making the parts of such materials as glass and chemically resistant plastics it tends to insure operation after rnany inactive years. The bearings of thc lockarmature and the escapement portion may be coated with materials to give these properties.

The parts of the link train are held together or prevented from coming apart by small side clearance to the case and other parts. Also, the spring I interferes with the links coming apart.

From the foregoing description of the embodiment of the invention illustrated in the drawings, it will be apparent to those skilled in the art that by this invention there is provided a circuit breaker that may be produced at considerably reduced cost as compared with present circuit breakers of comparable utility, and which is considerably more reliable in service.

It will be obvious that various changes may be made by those skilled in the art in the details of the embodiment of the invention illustrated in the drawings and described above within the principle and scope of the invention as expressed in the appended claims.

I claim:

l. In a circuit breaker of the kind described, the cornbination comprising a case, a stationary contact within the case, a movable link train within the case including an operating handle extending through one Wall of the case, a main-link and a latch-link connected to the handle and the main-link, the latch and main-link forming a toggle, resilient means acting to collapse the toggle, a movable lock element positioned to engage said latch link and prevent the toggle from collapsing under the ac- H tion of said resilient means, current responsive means carried by a link 0f said link train for actuating said lock to release said latch, and a movable contact cooperating with said stationary contact and movable away from the stationary contact upon the collapse of said toggle.

2. ln a circuit breaker of the kind described, the combination comprising a case, a stationary contact within the case, a movable link train within the case including an operating handle extending through one Wall of the case, a main-link and a latch-link connected to the handle and the main link, the latch and main-link forming a toggle, resilient means acting to collapse the toggle, a movable lock element mounted on the main-link and positioned to engage said latch-link and prevent the toggle from collapsing under the action of said resilient means, current responsive means carried by a link of said link train for actuating said lock to release said latch, and a movable contact carried by a link of said link train, positioned to cooperate with said stationary contact and movable away from the stationary contact upon the collapse of said toggle.

3. In a circuit breaker of the kind described, the combination comprising a case, a stationary contact within the case, a movable link train within the case including an operating handle extending through one wall of the case, a main-link and a latch-link connected to the handle and the main-link, the latch and main links forming a toggle, resilient means acting to collapse the toggle, a movable lock element mounted on the main-link and positioned to engage said latch-link and prevent the toggle from collapsing under the action of said resilient means, current responsive means carried by said main-link 'for actuating said lock element in a direction to release said latch, and a contact carried by said main-link, positioned to cooperate with said stationary contact and movable away from the stationary contact upon the collapse of the toggle formed by the main and latch links.

4. In a circuit breaker of the kind described, the combination comprising a case, a stationary Contact within the case, a movable link train within the case including an operating handle extending through one wall of the case, a main-link and a latch-link connected to the handle and the main-link, the latch and main links forming a toggle, resilient means acting to collapse the toggle, a movable lock element mounted on the main-link and positioned to engage said latch-link and prevent the toggle from collapsing under the action of said resilient means, a coil carried by a link of said link train and positioned to actuate said lock element in a direction to release said latch-link, and a contact carried by said main-link, connected to one end of said coil and positioned to cooperate with said stationary contact.

5. ln a circuit breaker of the kind described, operating mechanism including a link train comprising a first link, an intermediate link and a third link, the first link constituting a handle, the intermediate link constituting a latch, a contact carried by the third link, a coil carried by the third link and a lock-armature carried by the third link, the lock-armature being positioned to be attracted by said coil and having a portion for engaging said intermediate link.

5. In a circuit breaker' of the kind described, the combination comprising a case, a stationary contact within the case, a movable link train within the case including an operating handle extending through one wall of the case, a main-link and a latch-link connected to the handle and the main-link, the latch and main links forming a toggle, resilient means biasing the toggle to the collapsed position, a movable lock element positioned to engage said latch-link and prevent the toggle from collapsing under the action of said resilient means, current responsive means for actuating said lock to release said latch, a movable contact carried by said main-link and positioned to cooperate with said stationary contact, the main-link having a mass and rate of movement such that upon release of said .latch the Contact carried thereby separates from the stationary contact a distance of approximately twenty-five thousandths of an inch in no less than one-halt` cycle.

7. In a circuit breaker of the kind described, the combination comprising a case, a stationary contact within the case, a movable link train within the case inciuding an operating handle extending through one wall of the case, a main-link and a latch-link connected to the handle and the main-link, the latch and main links forming a toggle, resilient means acting to collapse the toggle, a movable lock element mounted on the main-link and positioned to engage said latch-link and prevent the toggle from collapsing under the action of said resilient means, a core carried by the main-link, a coil carried by the main-link about said core and positioned to actuate said latch-link, and a contact carried by the main-link connected to one end of the coil and positioned to cooperate with said stationary contact.

8. in a circuit breaker of the kind described, the combination comprising a case and operating mechanism within the case including a slidably and pivotally mounted link and a coil carried by the link.

9. In a circuit breaker of the kind described, the combination comprising a case and operating mechanism within the case including a movable link, a magnetically sensitive core extending through the link and forming a bearing for the link, and a coil carried by the link and positioned about the core.

l0. In a circuit breaker of the kind described, the combination comprising a case having slots in opposite walls thereof and operating mechanism within the case including a link, a core extending through the link and into the slots in the side walls of the case and slidably and pivotally mounting the link within the case, and a coil carried by the link and positioned about the core.

11. In a circuit breaker of the kind described, the combination comprising a case having slots in opposite walls thereof and operating mechanism within the case including a link, a core tube carried by the link and extending into the slots in the walls of the case and pivotally and slidably mounting the link in the case, a movable core within the core tube, and a ,coil carried by the link and positioned about the core tube.

l2. in a circuit breaker of the kind described, the combination comprising a case having slots in opposite walls thereof, a stationary contact within the case, and operating mechanism within the case including a link train comprising a pivotally mounted handle, a main-link and an l intermediate latch-link connected to the handle and mainlink and forming an overcenter toggle with the handle and an undercenter toggle with the main-link, resilient means acting to collapse the undercenter toggle, a movable lock element mounted on the main-link and positioned to engage said intermediate latch-link and prevent the toggle from collapsing unler the action of said resilient means, a core tube extending through the main-link and extending into the slots in the side walls of the case, a movable core within the core tube, a coil carried by the main-link positioned about the core tube, and a contact carried by the main-link, connected to one end of the coil and positioned to cooperate with said stationary contact.

References Cited in the tile of this patent UNITED STATES PATENTS 708,71() Hewlett Sept. 9, 1902 1,720,263 Chandler July 9, 1929 1,935,428 Atwood Nov. 14, 1933 2,182,773 Sachs Dec. 5, 1939 2,360,922 Wilckens Oct. 24, 1944 2,389,999 Rypinski Nov. 27, 1945 FOREIGN PATENTS 681,716 France Feb. 4, 1930