US2094964A - Automatic circuit breaker - Google Patents

Description

0a. 5, 1937. J, SACH 2,094,964

AUTOMAT IC CIRCUIT BREAKER Filed Dec. e, 1934 Y s sheets-sheet 1 d j .Ffgs

Oct. 5, 1937. J. sAcHs AUTOMATIC CIRCUIT BREAKER Filed Dec. 6, 1954 3v Sheets-Sheet 2 Oct. 5, 1937. J. sAcHs 2,094,964

AUTOMATIC CIRCUIT BREAKER Filed Deo. 6, 1934 I5 Sheets-Sheet 3 insu/swan dei 67 .w1/Eni: 0r.' JUSQU/7 Esa-fzs Patented Octf 5, 1937 t UNITED STATES PATENT AOFFICE 31 Claims.

The invention relates particularly to a circuit breaker having a current-carrying electrothermally responsive element which is deilectible to release the circuit breaker mechanism and to thereby permit automatic breaking of the circuit. In accordance with the invention, an auxiliary current-carrying electro-thermal heating device or means is directly associated with the electrothermally responsive releasing element so that upon the attainment of predetermined abnormal current conditions in the circuit the heating and deiiection of the releasingelement is dependent in part on its own electro-thermal characteristics and in part on the electro-thermal characteristics of the heating device.

A circuit breaker embodying the present invention is particularly adapted for motor starting and similar purposes, and it is ordinarily required that such a circuit breaker shall be capable of carrying a moderate overload for a predetermined short interval of time. This time interval of operation is readily obtained by reason of the relatively slow delecting of the bi-metallic or other thermally-responsive element as the result of the heat derived from the separate heating device, and by properly designing and locating the heating device any reasonable time interval can be obtained. Although the thermally-responsive element is only slowly heated by means of the external heating device under either moderate or excessive overload conditions, it is very quickly heated and deflected by an excessive overload current in the said element itself. Thus I very eiectively obtain the desired slow or delayed acticn of the circuit breaker under moderate overload conditions and the desiredA very quick or almost instantaneous action under excessive overload conditions.

It is one of the purposes of the invention to provide a circuit breaker which can be readily adjusted` or altered so that a single size and style of circuit breaker can be used for a wide range of capacities. When such a wide range of rated capacities is desired the electro-thermally deflectible releasing element, ordinarily a bi-metallic strip, is made of sufiicient capacity to carry, without operatively effective deflection, any current up to or even exceeding the maximum current that the circuit breaker is `intended to continuously carry; and the automatic circuit-opening operation of the circuit breaker at lower cur- 'rents is effected by providing an auxiliary current-carrying heating means consisting of a series of readily removable heating devices adapted to be interchangeably mounted in association with (Cl. 20o- 122) the deectible releasing element. The several' auxiliary heating devices are so designed that each of them serves, upon the attainment therein of the predetermined current for which that particular device is designed, to transmit suicient 5 additional heat to the releasing element to cause it to be deected suciently to operate the breaker. By this method the desired wide range of capacities is obtained, without in any way aiiecting or disturbing the required precision of construction and adjustment of the deflectible releasing element. Obviously the reliability and accuracy of operation of the circuit breaker would be seriously endangered if it were attempted to change the capacity of the circuit breaker by providing different deflectible releasing elements which would have to be handled, inserted and adjusted by inexperienced and unskilled persons.

While I prefer, for the reasons stated, that the deflectible releasing element be of the currentcarrying self-heating type, the invention, as to certain phases thereof, is not necessarily so limited. Whether the releasing element be current-carrying or not, I prefer to provide relative movement between the releasing element and the auxiliary heating device so that they are in close proximity when the circuit is closed but are more or less separated when the circuit is open. This result may be obtained in different ways, but I prefer to have the releasing element movable and to have the auxiliary heating device stationary., As to the details of mechanism, there may be wide variation, but I prefer a mechanism of the character shown and described in my copending application for Automatic circuit breakers, Serial No. 752,154, iiled November 8, 1934. With this construction the releasing element is a currentcarrying electro-thermally deectible bi-metallic element, and with the present invention I retain all of the advantages incident to a bodily movable element of the character referred to as set forth in the said application and in the prior patents and application therein referred to, and I also obtain the other advantages already outlined which resultfrom the combination of the auxiliary heating element with the deiiectible releasing element. In the type of construction referred to the movable contacts and associated parts move rectilinearly, but as to this I do not limit myself. e

The construction last referred to has the further advantage that after automatic operation of the circuit breaker the deflectible releasing element and the auxiliary heatingv device are more or less separated as the result of their relative movement, with the result that they can more quickly cool so as to permit reclosing of the circuit. A still further advantage resides in the fact that the relative movement of the releasing element and the heating device out of their normal relationship facilitates the removal of the latter for purposes-of inspection or replacement.

The general object of the present invention is to provide 'a circuit breaker having the features and advantages which have been herein briefly described. Further and more specic objects of the invention are to provide various features whereby these advantages are conveniently and economically obtained.

In the accompanying drawings I have shown one principal embodiment of the invention which I now deem preferable,vand I have shown three alternative forms of removable and interchangeable heating devices which may be used. It will be understood, however, that the drawings are intended for illustrative purposes only and are notto be construed as defining or limiting the scope of the invention, the claims forming a part of this speciiication being relied upon for that purpose.

Of the drawings:

Fig. 1 is a front elevation of a circuit breaker embodying the invention.

Fig. 2 is a View similar to Fig. 1 'with the front cover removed and with certain parts broken away to show other parts more clearly.

Fig. 3 is a top view.

Fig. 4 is a horizontal sectional view taken 'along the line f-ll of Fig. 6.

Fig. 5 is a vertical sectional View taken along the line 5 5 of Fig. 2 and also showing the front cover in place.

Fig. 6 is a vertical sectional view taken along the lines 6 6 of Figs. 2 and 4, this view showing the front cover in place and showing the circuit breaker mechanism in open-circuit position.

Fig. 7 is a view similar to Fig. 6, but showingl the mechanism in closed-circuit position.

Fig. 8 is a View similar to Fig. 7, but showing the handle held in closed-circuit position and showing the contact-carrying member in opencircuit position. p

Fig. 9 is a view similar to Fig. 6, but showing the front cover removed and showing the heating device partly removed.

Fig. 10 is a detail View showing separately the several parts of the contact-carrying member.

Fig. 11 is an enlarged front view showing the heating device separately.

Fig. 12 is a side view of the heating device shown in Fig. 11.

they constitute an enclosure.

Fig. 13 is an end View of the heating device shown in Figs. 11 and 12.

Fig. 14 is a fragmentary vertical sectional View taken along the line lll- I4 of Fig. 11.

Figs. 15 and 16 are views similar respectively to Figs. 11and 12 but showing an alternative heating device.

Figs. 17 and 18 are views similar respectively to Figs. 11 and 12 but showing another alternative heating device.

Referring to the drawings, I represents as an entirety the main insulating base or casing for the circuit breaker and 2 represents the front insulating cover. These parts are connected by suitable means, such as a screw 3, and together l Fig. 2 shows the circuit breaker with the front insulating cover 2 thereof removed.. The casing l is provided with holes d, l, andia for receiving screws for mounting the circuit breaker on a suitable support.

The main base or casing l has an opening or recess at the front and is closed or substantially closed at the rear.v A front guide plate 6 is provided which substantially closes the front opening in the casingA l. Resting upon the guide plate 6 are two conducting members 1 and 8 which are similar in construction except that they are right and left. The members 1 and d are held in place by means of screws 9, il and i6, lil which extend forward through the casing i and through holes in' the plate 6. The screws thus serve not only to hold the members 1 and 8 but also to hold the plate 6.

The member 1 is somewhat shorter than the member 8, and immediately below the said member 1, but insulated therefrom, is a wire terminal l l The member 8 is provided with a corresponding wire terminal l2 at the lower end thereof. If desired a neutral strap i3 may be provided having wire terminals l andl l5. The casing is vprovided with holes i6 and l1 to permit wires to be connected with the described terminals.

The members 1 and 8 are provided with rearward extending portions 1a and 8a which are positioned in suitably formed notches in the sides of the plate 6. Carried by and electrically connected with the said portions 'la and 8a are resilient conducting elements i8 and i9 which carry contacts 20 and 2|. The said contacts 20 and 2l are stationary except for such movement as is provided by the resiliency of their supports l and i9 and they will be hereinafter referred to as stationary contacts.

The members 1 and 8 are provided with forward projecting ears 1b and 8b which serveto support a lpivotally mounted handle 22. The handle is provided with hubs 22a having axially positioned pintles 23 seated inA bearing apertures .in the said ears 1b and 8b. A coil spring 2d surrounds one ofthe handle hubs and serves to bias the handle in the clock-wise direction. A portion of the handle 22 projects rearward through a slot 6a inthe plate 6. The handle is preferably formed of insulating material and it carries a metallic piece 25 adapted to be connected with operating links to be hereinafter described.

The contact carrying member of the circuit breaker is rectilinearly movable within the hollow interior of the casing I, the said member being guided at the front and held in place by means of the before mentioned guide plate 6. The said contact-carrying member preferably comprises two insulating plates 26 and 21 which are spaced apart transversely. The two plates 26 and 21 are adapted to engage at the front directly with the guide plate 6. At the rear there is preferably provided an auxiliary guide plate 28 seated in the bottom of the main recess in the casing I.

Two laterally projecting movable contacts 29 and 30 are carried by the contact member at the sides thereof, these contacts projecting laterally from the respective side plates 26 and 21 and being adapted to be engaged with and disengagedV portion of the contact fits the narrower portion of the corresponding slot 3|. Extending transversely between the two side plates is an insulating bar 32, the ends of which project into the wider portions of the slots 3| so as to hold the contacts in place. The inner ends of the contacts engage the bar 32 at the left hand side thereof as viewed in Fig. 10 and are held in place by means of rivets '33, 33. It will be observed that with the described construction the insulating bar 32 serves not only to hold the contacts 29 and 30 in place but also serves to hold the two side plates 26 and 21 in proper spaced relationship.

The two movable contacts 29 and 30 are electrically connected with each other, this electrical connection preferably being through an electrothermally responsive element which is carried by and is bodily movable with the contact member, By preference and as shown, this electro-thermally responsive element is a. bi-metallic thermostatic strip 34, mechanically and electrically connected directly with the two contacts. The contacts are provided with integral rearward extensions 29", 3|)b which extend through corresponding apertures in the strip. Washers 35, and 36, 36 may be provided and the rearward ends of the projections 29h, 3llb may be upset or i riveted over so as to hold the washers and the bimetallic strip in place. The bi-metallic strip 34 is adapted to serve as a latch as will be presently explained, and in order that it may more eiectively so serve it is vprovided with an opening at 34a and may carry a wear piece 31 which is riveted in place and which is formed with a forward extension which extends through the opening 34a.

From the foregoing description it will be apparent that the contact member is movable rectillnearly as guided by the plates 6 and 28, and that in so moving it serves to bring the movable contacts 29 and 30 into or out of engagement with `the respective stationary contacts 20 and 2| to make or break the circuit. member is in the upper contact engaging position as shown in Figs. 2, 5, and 7 electrical connection is established between the conducting members 1 and 3; and when the contact member is in the lower position as shown in Figs.

6 and 8 the circuit is broken at two places, that is between the contacts 20 and 29 and between the contacts 2l and 30.

A suitable spring means is provided for biasing the contact member in the downward or circuit-opening direction. Preferably and as shown threnisprovided a torsional coil spring 36 positioned'ia suitable auxiliary recess near the rear of thev casing I, and held in place by a cross bar 39 and a screw 40. At the ends of the spring are two integral arms 33, 3|iil which extend forward and bear directly against the upper ends of the plates 26 and 21. v

yFor actuating the contact member for normal switching purposes, or' to effect closing of the circuit after automatic opening thereof, I provide a member which I shall term an actuating member or actuator. 'Ihis member is normally engaged by the thermostatic strip or latch 34, and the actuator is'so positioned and connected that a portion of the stress of actuation'is transmitted directly from the actuator to the contact member independently of the thermostatic latch.

The actuator is shown at 4|, and it is pivoted to the contact member for movement about a transverse axis in fixed relationship thereto. As illustrated and as preferred, the actuating member 4| is of bell crank form and consists of a metallic When the contact y ator 4|.

plate pivotally mountedron a pin 42 extending transversely between the two side plates 26 and 21. Spacing bushings 43, 43 hold the actuator inl central position. A shoulder 4| on the actuator 4| is adapted to engage the plate 6 and to thus limit relative movement of the actuator in the clock-wise direction. The actuator is provided with a tooth 4|b which, at normal temperatures, is engaged by the wear piece 31 on the thermostatic latch 34. With the parts in the relative positions shown in Fig. 6, the actuator and the contact member are positively connected to move in unison.

The handle or operating member 22 servesY as the means for manually operating the actuator 4|. The metallic piece 25 on the handle member 22 is connected with the actuator. by means of two similar links 44, 44, the links being pivoted to the handle at 45 and to the actuator at 46.

When the parts are in the relative positions shown in Fig. '7 the links 44 cooperate with the handle 22 to form a toggle which locks the parts in position with the movable contacts 29 and 30 pressed into ilrm engagement with the stationary contacts 20 and 2|. Continued movement of the handle in the counter-clockwise direction is prevented by the engagement of an extension 25*l on the metallic piece 25 with the front guide plate 6 as shown in Fig. 7. 'I'he pivotal axis at 45 is at the left of a straight line connecting the pivotal axes at 23 and 46, and thus the handle member 22 and the links 44 serve to resist the tendency of the contact member to move downward under the influence of the spring 38 and of gravity. The spring 38 is suiilciently powerful to enable the said toggle action to hold the handle or operating member 22 in its lower or closed-circuit position, the toggle action resisting the tendency of the spring 24 to move the said member in the clockwise direction to its open-circuit position.

The above described toggle action can be released by pressing the handle upward, the parts then moving under the action of the springs 33 and 24 to the open-circuit position shown in Fig. 6. The movable contacts 29 and 30 are thus disengaged from the stationary contacts 20 and 2| Aand the circuit is broken in two separate places. By moving the handle toward the downward position the several parts can be restored to their respective closed-circuit positions, as shown in Fig. 7, and the circuit can be thus re-established.

As before explained, the bi-metallic strip 34 is electrically connected between the movable ' contacts 29 and 30. It is adapted to be deflected rearward upon the passage vof excess current therethrough, with the result that the wear piece 31 is disengaged from the tooth 4|h of the actuator 4| to turn slightly relatively to the contact member in the counter-clockwise direction. This slight movement changes the relation of the togglelinksA 44 and 22 and reduces the pressure `which had theretofore served to hold the links 44 and thehandle member 22 in their effective toggle relationship. This change in relationship and reduction in pressure permits the handle member 22 to move in the clockwise direction so as to render the toggle ineffective. Thus both the contact member and the handle are freed and both of them moveto their open-circuit positions under the influence of their respective springs. contact member and the handle move, substan- Such disengagement permits the actu- It willbe understood that normally theA tially simultaneously with the result that the latch and the actuatorv may never be actually completely disengaged from each other. When the .parts reach their full open-circuit position as shown in Fig. 6 'the latch and the actuator are in position to fully re-engage as soon as the thermostatic strip is sufficiently cooled.

As stated, the electro-thermally responsive releasing element is preferably a bi-metallic strip, but the invention is notl necessarily so limited; and therefore the words deflect and derivatives thereof, as applied to the said releasing element, are used generically to mean any distortional movement and are not limited to a. bending distortion.

The circuit-opening movement of the Contact member is not in any way dependent on the circuit-opening movement of the handle member and will, in fact, occur even though the handle member be held in its closed-circuit position, as shown in Fig. 3. The rearward deection of the thermostatic-strip 34% permitsthe actuator di to turn in the counter-clockwise direction as already stated, even though the handle is held, thus releasing the contact member from the control of the handle member 22 and oi the links lit. The contact member moves downward to the position shown in Fig, 8, the actuator M and the links ill assuming the relative positions shown in that figure. having been held as described, be now released, it will move under the influence of the spring 2d to its open-circuit position as shown in Fig. 6, thus bringing the actuator lll into its normal position with respect to the Contact member so that the tooth lib is automatically engaged by the latch Sli.

It will be observed that the contact member together with the actuator and the bi-metallic thermostatic latchcarried by the said contact member constitute a movable self-contained unit. The movement of this self-contained unit is guided and controlled by the two guide plates S and 28, but inasmuch as the actuator is carried directly by the side plates of the contact member any looseness at the guide plates willin no way aiect the accuracy or the operating characteristics of the circuit breaker. plained, the actuator il is pivoted to the Contact member at 62, and the actuator and the bimetallic latch 3G normally remain in fixed relationship with each other and with the contact member, there being no relative movement at the bearing 62 except upon automatic opening of the circuit breaker and even then the movement is normally very slight.

Preferably, as shown in Figs. 2 and 5, I provide in the rear wall of the casing I immediately behind the engaged positions oi the contacts 20, 29 and 2|, 30 holes t1, 47. Registering holes are provided in the plate 28. The holes 4l are useful for inspection purposes during the assembly and testing of the circuit breaker. By looking throughthe holes it is possible to observe whether the movable contacts 29 and 3B properly engage the stationary contacts 20 and 2l. After assembly and inspection are complete the holes 41 may be closed by means of sealing wax or other suitable material as indicated at 48.

The mechanism as thus far described is similar in the main to that shown and described in my before-mentioned application Serial No.,752,154. In accordance with the present invention, I associate with the described mechanism, or with an equivalent mechanism, an auxiliary heating If the handle 22, after As already exdevice or means which is so positioned as to transmit heat to the thermally responsive ureleasing element of the mechanism. When the re leasing element carries current and. is electrothermally responsive the auxiliary heating device is preferably connected in series therewith, although the invention is not necessarily so limited. The said releasing element and thesaid heating device are shown as being relatively movable, and in the present instance it is the releasing element which moves, the heating de-l vice being stationary.

In the breaker shown in the said prior application the wire terminals corresponding to the. terminals it and i2 are electrically connected directly with the stationary contacts corresponding to the contacts 2@ and 2l. In the present circuit breaker, however, only one of the terminals, as for instance the terminal i2, is electrically connected directly with the corresponding stationary contact and the other terminal,

i' connection between the strap 52 and the conducting member l. The attachment terminal 56 is connected by means of a conducting strap 53 with a screw 56 `which extends forward through a hole in the base. This screw 5t is connected by means of a threaded sleeve 55 with the screw which constitutes a part of the wire terminal li.

Mechanically and electrically connected with the attachment terminals t9 and 5t is a heating device which is readily removable and replaceable and which is preferably readily interchange-y able with other heating devices mechanically` similar but having diierent heating characteristics. The heating devices may be widely varied as, to details of construction, but I prefer devices of the character shown in the drawings. Three varieties of such heating devices are illustrated,v and these will now be described.

The heating device shown in Figs. 2, 3, 5, 6, 7, 8, and 9 of the drawings is shown enlarged and-in greater detail in Figs. 11 to 14. The said heating device comprises two adjacent connection members 56, 56 which are adapted for mechanical and electrical connection with the attachment terminals 49 and 50. As shown, each of these connecting members is, an eyelet or bushing adapted to fit over the correspondingattachment terminal screw. Associated with each bushing is a nut 51 for engaging the correspond- Y ing screw and for providing mechanical and electrical connection between the screw and the connection member. The heating element proper of the heating device is a resistance element or wire 58 having its end portions 58B, 58 connected with the connection members 56, 56. 'Ihe exact shape of the resistance element 58 may be place.

constitutes a support therefor.

When the resistance element is so shaped or bent the heating device comprises two transversely spacedsubstantially parallel heating portions.

' The two - connection members 56, 56 are mechanically connected with each other. Associated with each member is a bracket 59 and each of the said members extends through aA suitable hole in an angularly extending portion 59"L of the corresponding bracket. The two brackets 59, 59 are connected, by riveting or otherwise, to a transverse insulating member 60. In addition to the parts already described there is provided a spacing insulating Washer 6| on each bushing 56, and a sheet 62 also of insulating material is provided which overlies the portion 58c of the resistance wire to hold it in s It will be understood that initially only one end of the bushing 56 is flanged, and that the other end is bent or spun into position after the various other parts are in place.

Preferably each bracket 59 has a second angularly extending portion 59b which is notched Yto receive the corresponding nut 51. r'he end of each notch is 'narrower than the diameter of the nut, and the nut must be forced or snapped into place, so that it is retained but left free to rotate. Preferably the angularly extending portion 59a of each bracket 59 is provided with a finger 59C which extends between the two portions *58a and 58D of the resistance wire 58 and The portions of the wire are insulated from the support 59c by means of sheets of mica or other insulating material 63 and 64. y

'I'he heating effectiveness of the heating device may be varied considerably by changing the character or the size of the resistance wire 58;

'but if an increase in heating effectiveness is desired greater than can beconveniently obtained by merely changing the character or the size' `of the wire, this may be obtained by coiling portions of the wire as shown` in Figs. and 16. The construction shown in these two figures is identical with that shown in Figs; 1I to 14, with the exception that there is provided a wire 65 having the front portions thereof coiled as shown at 65h.

When less heating effectiveness is desiredl and a very\heavy resistance wire is used, it is possible to simplify the construction considerably by omitting the supports 59". A heating device of this type is shown in Figs. 17 and `18. The resistance wire 66 is similar to the Wire 58 except that it is heavier. Insulating washers 61 and 68 are provided on the bushings 56, and a transverse plate 66 is also held by the bushings and serves to suDpOgrb the transverse portion 66c of the Wire 66.

The rated capacity of the circuit breaker is dependent upon `the particular heating device which is in place therein, and I therefore prefer to clearly mark the saidi'rated capacity on the heating device. This ma'rking is placed on the insulating member 60, and as illustrated in Figs. 3 and 13 the marked rating is 2.00, meaning 2 amperes. The cover 2 of the casing is provided with an opening at 10 which makes it possible for the marking to be observed from the exterior of the casing. l

When the heating device is in place and when the circuit breaker is in closed position, as shown in Fig. 7, the heating element of the heating device is in close proximity vto the bi-metallic releasing element 34. The heating element extends between the insulating side plates of the contact member and the two transversely spaced portions of the heating element are at opposite sides of the actuator 4i. The heating portions of the heating element are in close proximity to the deflectible releasing element 34 and to guard against any possible contact therewith it may be desirable to provide a sheet 1i of mica or other insulating material on the element 34. This sheet, when provided, is held in place as shown in Fig. l0 by the rivet 1|ab and by auxiliary washers 1lb, 1lb.

In order to remove the heating device it is necessary to first remove the cover 2 as shown in Fig. 9. With the contact member and the releasing element 34 in their open circuit position as turning the nuts 51, 51. Then the device can be readily removed as shown, the insulating member f 60 serving as a convenient handle. A new or different device can readily be put in place. It will be observed that the nuts 51, 51 are retained in position on the heating device, and that removal and replacement of the heating device is thereby greatly facilitated.

It will be apparent from the drawings and the foregoing description that the heating device is connected in series with the other conducting parts of the circuit breaker and that the entire current passing through the breaker iiows through the heating device. The heating device, by reason of its proximity to the bimetallic releasing element 34, heats the said element and causes a deection thereof to an extent greater than would be caused by the direct heating .action of the current in the said element. Upon being sufiiciently heated, whether directly by internal current or indirectly by heat transmitted from the heating device, the element 34 is deflected sufficiently to release the mechanism and. permit the circuit breaker to automaticallyy open. y y

After automatic opening, the releasing element 34 and the heating device are somewhat separated from each other as shown in Figs. 7 and 8 and this facilitates their more rapid cooling. It will v be evident from an inspection of Fig. 8 that it is necessary'for the element 34 to cool and return to approximately its normal condition before it can be re-engaged with the actuator 4I.

As has already been pointed out, the defiectible releasing element 34 may be made relatively heavy and may be so designed that it would not be operatively deflected by currents therein up to or even exceeding the maximum current that the circuit breaker is intended to continuously carry, even at the maximum rated capacity. Each auxiliary heating element is so designed that, upon the attainment therein of the particular predetermined overload current at which it is desired for the circuit breaker to automatically open, it becomes heated sufficiently to additionally heat and thereby deflect the releasing element 34. A certain time is required for the heat of the heating device to be transmitted to the releasing element and therefore the automatic opening of the circuit breaker is delayed. This interval of delay can be predetermined by properly spacing the heating device with respect to the releasing element. If the overload current is of shorter duration than the prescribed interval of delay, the circuit breaker will not open.

It will be evident that for a rated capacity which is at or near the maximum capacity for the particular circuit breaker the direct heating action in `the releasing element 34 may be nearly sufficient to cause automatic opening and that only a small amount of additional heating by the auxiliary heating device is required.` However,- for the smaller rated capacities the direct heating effect of the current in the releasing element 341 isI less" and a correspondingly greater heating by w the auxiliary heating element is required.` The required heating effect of the heating device varies inverselyv with the rated capacity. It will therefore be understood that in accordance with my invention and particularly my novel method the deilectible element 34 is heated directly by the current therein to an extent varying directly with the amount of the overload current at which automatic opening is to occur, and is heated indirectly by the current in the auxiliary heating device to an extent varying inversely with the amount of overload current at which automatic opening is lto occur. The conducting characteristics of the deilectible element are maintained unchanged, and the heating effectiveness of the auxiliary heating means is varied inversely with the variation in the rated capacities.

In the event of an excessive overload, the heating effect of the current in the releasable element itself is suiicient to cause the said'element to be very quickly deflected Without waiting for heat to be transmitted from the auxiliary heating device. 'Ihis causes the circuit breaker to quickly vopen regardless of the particular auxiliary heating device that may be in use, and in this Way the heating device is protected from the continued ilovv therein of an vexcessive -cur-- rent which might eventually damage it.

What I claim is:

1. 'I'he combination in an automatic circuit breaker, of a stationary contact, a movable contact member having a contact adaptedto engage and disengage the stationary contact, the said contact member being normally mechanically held against movement toward its open-circuit position, a bi-metallicv element supported upon deflectible by heat to mechanically release the contact member and permit it to move to opencircuit position, means for automatically moving the contact member to its open circuit position when it is so released and a stationary currentcarrying heating device adjacent the closed-circuit position of the bi-metallic element and serving upon the attainment of predetermined abnormal current conditions in the circuit to heat the said` element so as to cause the release of the contact member, the said heating device being supported at one end only and extending from its support in the general direction of movement of the bi-metallic element.'

2.- The combination in an automatic circuit breaker, of a stationary contact, a movable contact member having a contact adapted to engage and disengage the stationary contact, the said contact member being biased for movement toward its open-circuit position and being normally mechanically held against such movement, a bi-metallic element supported upon and bodily movable with the contact member and deilectible by heat'to mechanically. release the contact member and permit it to automatically move to opencircuit position, a current-carrying heating device constituting a self-contained removable and interchangeable unit, and stationary means for detachably supporting the heating device unit at one endonly so as to extend in the general direction of movement of the bi-metallic element, the said supporting means holding the heating device in a xed position adjacent the closed.

it may serve upon the attainment of predetermined abnormal current conditions in the circuit to heat the said element so as to cause the release of the contact member.

3. The combination in an automatic circuit breaker, of a stationary contact, a movable contact member having a contact adapted 'to engage and disengage the stationary contact, the said 'contact member being biased toward its open-circuit position, a movable actuator, a bimetallic releasable latch movable with' the actuator and the contact member and normally connecting the latter with the ,former for circuit opening and closing movements, the said latch being deflectible by heat to mechanically release the contact member from the actuator, and a stationary current-carrying heatingdevice adjacent the closed-circuit position of the bimetallic latch and at the same side thereof asthe actuatonthe said heating device serving upon the attainment of predetermined abnormal currentoconditions in the circuit to heat the latch and thereby deiiect it so as to cause the release of the contact member.

4. The combination in an automatic circuit breakenof a stationary contact, a movable contact member having a contact, means for guiding the contact member for rectilinear movement to enable the contact thereof to engage and disengage the stationary contact, means for biasing `the said contact member toward its open-circuit l position, a movable operating member normally adapted to move the contactmember to open or close the circuit, a bi-metallic element deilectible by heat and a current-carrying heating ,device one of which'is iixed against bodily movement and the other of which is bodily movable rectilinearly -with the contact member so that the said element and the said device are in close proximity when the contact member is in its closed-circuit position, the 'said heating device serving upon the attainment ofv predetermined abnormal current conditions in the circuit to heat the deilectible bi-metallic element and the said element When heatedA being deectedto mechanically release the contact member fromthe operating member and permit it to automatically move rectilinearly to open-circuit position.

5. The combination in an automatic circuit breaker, of a stationary contact, a movable contact member having a contact, means for guiding the contact member for rectilinear movement to enable the contact thereof to engage and disengage the stationary contact, means for biasing the said contact member toward its open-circuit position, a lmovable actuator, a bi-metallic releasable latch movable rectilinearly with the actuator and the contact member and normally connecting the latter with the former for circuit opening and closing movements, the said latch being parallel to its direction of movement `and being deflectible by heat to mechanically release the contact member from the actuator, and a stationary current-carrying heating device parallel to and adjacent the closed-circuit position of the bi-metallic latch and serving upon the attainment of predetermined abnormal current conditions in the circuit to heat the latch and Vthereby deflect it so as tovcause the release of the contact member for automatic rectilinear movement to open-circuit position.

6. The combination in an automatic circuit breaker, of a stationary contact, a movable contact -member having a contact, means for guiding the contact member for rectilinear movement to enable the contact thereof to engage and disengage the stationary contact, means for biasing the said contact member toward its open-circuit position, a movable actuator, abi-metallic releasable latch movable rectilinearly with the actuator and the contact member and normally connecting the latter with the former for circuit opening and closing movements, the said latch being parallel to its direction of movement and being deilectible by heat to mechanically release the contact member from the actuator, a stationary current-carrying heating Adevice constituting a self-contained removable vand interchangeable' unit, and means for detachably mounting the heating device unit in a fixed position parallel to and adjacent the closed-circuit position ofthe bi-metallic latch so that it may serve upon the attainment of predetermined abnormal current conditions in the circuit to heat the latch and thereby deflect it so as to cause the release of the contact member for automatic rectilinear movement to open-circuit position.

7. In an automatic circuit breaker, the combination of a stationary contact, a movable contact member having a contact adapted to engage and disengage the stationary contact, the said contact member being normally mechanically held against movement toward its open-circuit position, a current-carrying deflectible element and an auxiliary current-carrying heating device one of which is fixed `against bodily move` ment and the other of which is bodily movable with the contact member so that the said element and the said device are in close proximity when -the contact memberI is in its closed-circuit position and are out of the 'said close proximity when the contact -member is in its open-circuit position, the said defiectible element being adapted to be heated and deflected by current therein and the said heating device serving to" additionally heat and deflect the deectible element, and means serving -to release the contact member to 'permit circuit opening movement thereof when the deflectible element is heated and deected to a predetermined extent as the result of predetermined excess current conditions in the circuit.

8. In an automatic circuit breaker, the combination of two stationary contacts, a movable contact member having two contacts adapted to engage and disengage the respective stationary contact, the said contact member being biased for movement toward its open-circuit position and being normally mechanically held against such movement, a current-carrying deectible element and an auxiliary currentcarrying heating device one of which is fixed against bodily movement and the other of which is electrically connected between the movable contacts and is bodily movable with the contact member so that'the said element and the said device are in close proximity when the contact member is in its closed-circuit position and are out of the said close proximity when the contact member is in its open-circuit position, the said deflectibleelement being adapted to be heated and deflected by current therein and the said heating device serving to additionally heat and deflect the deilectible element, and means serving to release the contact member to permit automatic circuit opening movement thereof when the dee'ctible element is heated and deflected to a predetermined extent as the result of predetermined excess current conditions in the circuit.

9. In an automatic circuit breaker, the `confibination of a stationary contact, a movable contact member having a Contact adapted to engage and disengage the stationary contact, the said contact member being biased for movement toward its open-circuit position and being normally mechanically held against such movement,

a stationary current-carrying heating device, andv a current-carrying bi-metallic element supported upon and bodily movable with the contact member and deectible by heat to mechanically release the contact member and permit it to automatically move to open-circuit position, the said bi-metallic element being in close proximity to the said heating element so as to be heated thereby when in closed-circuit position and being out of the said close proximity when in open-circuit position and the heating and deflection of the said element when in closed-circuit position and upon the attainment of predetermined abnormal `current conditions in the circuit being dependent in part on its own electro-thermal characteristics and in part on the electro-thermal characteristics of the heating device.

10. In an automatic circuit breaker, the combination of `a stationary contact, a movable contact member having a contact, means for guiding the contact member for rectilinear movement to enable the contact thereof to-engage and disengage the stationary contact, means for biasing the said contact member toward its open-circuit position, a current-carrying bi-metallic releasable latch supported upon and bodily movable with the contact member, the said latch normally preventing movement of the contact member to its open-circuit position andV being deflectible by heat to release the contact member and permit it to automatically so move, and a stationary current-carrying heating device positioned to transmit heat to the latch when the latter is in its closed-circuit position so that upon the attainment of predetermined abnormal current conditions in the circuit the heating and deflection of the' bi-metallic latch is dependentl in part on its own electro-thermal characteristics and in part on the electro-thermal characteristics ofL the heating device.

11. In an automatic circuit breaker, the com bination of a stationary contact, a movable contact member having a Contact adapted to engage and disengage. the stationary contact, the said contact member being biased for movement toward its open-circuit position and being normally mechanically held against such movement, a stationary current carrying heating device, a current-carrying bi-metallic element supported upon and bodily movable with the contact member and deflectible by heat to mechanically release the contact member and permit it to automatically move to open-circuit position, the said bi-metallic element being in close proximity to the said heating element so as to be heated there by when in closed-circuit position and being out of the said close proximity when in open-circuit position and the heating and deflection of the said element when in closed-circuit position and upon the attainment of predetermined abnormal current conditions in the circuit being dependent in part on its own electro-thermal characteristics and in part on the electro-thermal characteristics of the heating device, and an insulating sheet adjacent and movable with the bi-metallic element and interposed between the said element and the said heating device.

.release the contact member and permit it to autol matically move to open-circuit position, a stationary current-carrying heating device constitutling a self-contained removable and interchangeable unit, and means for detachably mounting the heating device unit in a fixed position adjacent the closed-circuit position of the bi-metallic element, the said mounting means serving to electrically connect the heating device so as to constitute a part of the circuit.

13. In an automatic circuit breaker, the combination of a stationary contact, a movable contact member having a contact adapted to engage and disengage the stationary contact, the said contact member being biased toward its opencircuit position, a movable operating member normallyv adapted to move the contact member to open or close the circuit, a current-carrying deectible element and a current-carrying heating device one of which is xed against bodily movement and the other of which is bodily movable with the contact member so that the said element and the said device are in close proximity when the contactmember is in its closed-circuit position and are out of the said proximity when the contact member is in its open-circuit position, the said deiiectible element being adapted to be heated and deected by current therein and the said heating device serving to additionally heat and deect the deiiectible element, and means serving to mechanically release the contact member from the operating member and permit it to automatically move to open-circuit position when the defiectible element is heated and deflected to a predetermined extent as the result of predetermined excess current conditions in the circuit.

14. In an automatic circuit breaker, the combination of a stationary contact, a movable contact member having a contact adapted to engage and disengage the stationary contact, the said contact member being biased for movement toward its open-circuit position, a movable actuator normally adapted to move the contact member to open ory close the circuit, a currentcarrying bi-metallic element normally movable with the actuator and the contact member and deectible by heat to mechanically release the contact member from the actuator and permit it to move automatically to open-circuit position, and a stationary current-carrying heating device positioned adjacent the closed-circuitposition of the bi-metallic element and at the same side of the said element as the actuator, the said heating device serving to transmit heat to the bi-metallic element when the latter is in its closed-circuit position so that upon the attainment of predetermined abnormal current conditions in the'circuit the heating and deflection of the bi-metallic element is dependent in part on its own electro-thermal characteristics and in part on the electro-thermal characteristics of the heating device. y

15.' In an automatic circuit breaker, the combination of two stationary contacts, a movable aoaaaea contact member having two contacts adapted to engage and disengage the respective stationary l contact, the said contact member being biased for movement toward its open-circuit position, a movable actuator normallyadapted to move the contact member to open or close the circuit,

a current-carrying bi-metallic releasable latch movable with the actuator and the contact member and electrically connected between the movable contacts, the said latch normally enabling the actuator to move the contact member and being deflectible by heat to release the contact member from the actuator and permit it to move automatically to open-circuit position, and a stationary current-carrying heating device positioned to transmit heat to the bi-metallic latch when the latter is in its closed-circuit position so that upon the attainment of predetermined abnormal current conditions in the circuit the heating and deflection of the bi-metallic latch is dependent in part'on its own electro-thermal characteristics andv in part on the electro-thermal characteristics of the heating device.

16. In an automatic circuit breaker, the combination of a stationary contact, a movable contact member having a contact adapted to engage and disengage the stationary contact, the

said contact member being biased for movement toward its open-circuit position, a movable actuator normally adapted to move the contact member to open or close the circuit, a currentcarrying bi-metallic element normally movable with the actuator and contact member and deectible by heat to 'mechanically release the contact member from the actuator and permit it to move automatically to open-circuit position, a stationary current-carrying heating device constituting a self-contained removable and interchangeable unit, and means for detachably mounting the heating device unit in a iixed position adjacent the closed-circuit position of the bi-metallic element, the said mounting means serving to electrically connect the heating device so as to constitute a part of the circuit.

17. An automatic circuit breaker comprising in combination, two stationary contacts, a movable contact member comprising two parallel spaced insulating plates and having two spaced contacts adapted to engage and disengage the stationary contact, the said contact member being biased for movement toward its open-circuit position and being normally mechanically held against such movement, a bi-metallic element supported upon and bodily movable with the contact member and deectible by heat to mechanically release the contact member and permit it to automatically move to open-circuit position, and a stationary comprising two parallel spaced insulating plates and the said member being biased toward its open-circuit position and being normally mechanically held against such movement, a bimetallic element supported upon and bodily movable with the contact member and deflectible by heat to mechanically release' the contact member and permit it to automatically move rectilinearly to open-circuit position, and a stationary current-carrying heating device positioned to extend between the said insulating plates when the contact member is in its'closed-circ'uit position, the said heating device being substantially parallel with the direction of movement of the bimetallic element and serving upon the attainment ofypredetermined abnormal currentconditions in the' circuit to transmit heat to the said element and to thus deflect it. A

19. The combination in an automatic circuit breaker, of two stationary contacts, a movable contactmember comprising two parallel spaced insulating plates and having two spaced contacts adapted to engage and disengage the respective stationary contacts, the said contact member being biased for movement toward its open-circuit position and being normally mechanically held against such movement, a current-carrying bi-metallic element supported upon and bodily movable with the contact member and deectible by heat resulting from current therein so as to mechanically release the lcontact member and permit it to automatically move to open-circuit position, and a stationary current-carrying heating device positioned to extend between the said insulating plates in close proximity to the bimetallic element when the contact member is in its closed-circuit position, the said heating device serving upon the attainment of predeter- `mined abnormal current conditions in the circuit to additionally heat and deflect the said bimetallic element.

20. The combination inv an automatic circui breaker, of two stationary contacts, a movable contact member comprising two parallel spaced insulating plates -and having two spaced movable contacts, the said member being biased toward its open-circuit position, a movable actuator pivotally mounted between and bodily movable with the insulating plates, a currentcarrying bi-metallic latch supported upon and bodily movable with the contact member andI normally engaging the actuator to prevent relative pivotal movement thereof, the said latch being deiiectible by heat resulting from current therein so as to disengage the actuator and permit relative pivotal movement thereof, means engaging the actuator for normally moving it and the contact member to open and close the circuit, and a stationary current-carrying heating device positioned to extend between the said insulating plates in close proximity to the closed-circuit position of the bi-metallic latch and at the same side of the said element as the actuator, the said heating device serving upon the attainment of predetermined abnormal current conditions in the circuit to additionally heat and deflect the said bimetallic latch.

21. An automatic circuit breaker comprising in combination, two normally engaged electric contacts one of which is movable to disengage and engage the other, releasable means normally serving to prevent disengaging or circuit-opening movement of the movable contact and having in association therewith an element deflectible by heat and serving upon deilection to effect release of the said releasable means and thereby permit such circuit-opening movement, two threaded attachment terminals electrically connected in the circuit, and an auxiliary heating device constituting a self-contained readily removable and interchangeable unit adapted to be positioned to transmit heat to the said deilectible element uponA the attainment of predetermined abnormal current conditions in the circuit, the said heating device unitv including two rotatable threaded nuts normally permanently connected therewith independently of their threads and adapted to engage the threaded attachment terminals to provide mechanical and electrical connection therewith.

22..'I'he combination in an automatic circuit breaker, of two normally engaged electric contacts one of which is movable tofrdisengage and engage the other, releasable means normally serving to prevent disengaging or circuit-opening movement of the movable contact and having in association therewith a bi-metallic element defiectible by heat to effect release of the said releasable means and thereby permit circuit-opening movement, and a-current-carry-V. ing heating device having two transversely spaced substantially parallel portions extending longitudinally of the bi-metallic element and closely adjacent thereto, the said heating device serving upon the attainment of predetermined abnormal current conditions in the circuit to heat and deflect the said bi-metallic element.

23.*The combination in an automatic circuit breaker, of a stationary contact, a movable con'- tact member having a movable Contact thereon and biased toward its open-circuit position, a movable actuator, a bi-metallic latch supported -upon and bodily movable with the contactmember and normally engaging the actuator, the said latch being deectible by heat so as to disengage the actuator and permit movement of the contact member separately from the actuator, means engaging the actuator for normally moving it and the contact member to open and close the circuit, and a stationary current-carrying heating device having two spaced portions positioned to extend longitudinally of the bi-I'netallic latch in close proximity thereto and at opposite sides oi' the actuator when the contact member is in its closed-circuit position, the said heating device serving upon the attainment of predetermined abnormal current conditions in the circuit to heat and deflect the said bi-metallic latch.

24. The combination in an automatic circuit breaker, of two stationary contacts, a movable contact member comprising two parallel spaced insulating plates and having two spaced movable contacts, the said member being biased toward its open-circuit position, a. movable actuator positioned between and movable with the insulating plates, a bi-metallic latch supported upon and bodily movable with the contact member and normally engaging the actuator, the said latch being deilectible by heat so as to disengage the actuator and permitY movement of the contact member separately from the means engaging the actuator for normally moving it and the contact member to open and close the circuit, and a stationary current-carrying heating device having two spaced portions positioned to extend between the said insulating plates at opposite sides,

of the actuator and in close proximityto the bi-metallic latch when the contact member is in its closed-circuit position, the said heating device serving upon the attainment of predetermined abn'ormal current conditions in the circuit to heat and deflect the said -lai-metallic latch,

25. The combination in an automatic circuit breaker of a main base or casing, two normally engaged electric contacts one of which is fXedly y'.and means for detachably holding the heating device in place independently of the bi-metallc element and with the handle portion projecting as aforesaid, the last said means also serving to electrically connect the heating .element of the device into the circuit of the circuit breaker.

26. The combination in an automatic circuit breaker of an enclosure comprising a main base or casing and a removable cover, the said enclosure having an opening therein, two normally engaged electric contacts one of which is nxedly mounted on the casing and the other of which is biased for disengaging circuit opening movement, releasable means normally serving to prevent circuit-opening movement yof the movable contact and having in association therewith a bi-metallic element deectible by heat toeiect release ofthe said releasable means and thereby permit circuit-opening movement, a self-contained structurally separate heating device com'- prising a heating element normally positioned in close proximity to the bi-metallic element and also comprising an insulating handle portion v which projects at an angle to the plane of the Gil heating element so 'as to be readily accessible when the cover is removed, the said projecting portion having a marking thereon to indicate rated capacity which marking is positioned to be exposed and visible through the said openingin the enclosure, and means for detachablyhold- `ing the heating device in place independently of the bi-metallic element and with the handle portion projecting as aforesaid, the last said means also serving to electrically connect the heating element of the device into the circuit of the circuit breaker.

27. The combination in an automatic circuit breaker of a main base or casing, two normally engaged electric contacts one of which is xedly mounted on the casing and the other oi which is biased for disengaging circuit opening movement, releasable means normally serving to prevent circuit-opening movement of the movable contact and having in association therewith a bimetallic element deiiectible by heat to eect release of the said releasable means and thereby permit circuit-opening movement, a self-contained structurally separate heating device comprising a heating element normally positioned in close proximity to the bi-metallic element and also comprising an insulating portion which projects forward atan angle to the plane of the heating element and beyond the front plane of the casing so as to be readily accessible, the said projecting portion having a marking thereon to indicate rated capacity, means for detachably holding the heating dence in place independently 0f the bi-metallic element and with the handle portion projecting forward as aforesaid, the last said means also serving to electrically connect the heating element of the device into the circuit of the circuitbreaker, and a removable front cover I normally tting the casing and cooperating therewith to enclose various parts of the circuit breaker, the said cover having an opening through which the marking onthe projecting portion of the heating device is exposed when the cover is in place. -l v 28. A readily `removable and interchangeable heating device unit for an automatic circuit breaker comprising in combination a currentcarrying heating element and two rotatable threaded nuts normally permanently connectedl with the heating element independently of their threads and adapted to engage threaded attach- .ment terminals to provide mechanical and electrical connection therewith.

29. A readily removable and interchangeable heating device unit for an automatic circuit breaker comprising in combination two adjacent conducting connection members spaced apart and adapted for mechanical and electrical connection with attachment terminals, and a U-shaped current-carrying 'heating element having the end portions of its legs electrically'and mechanically connected with the said connection members and having the outer portions thereof extending backward in approximate parallelism with the said end portions so that the transverse portion of the U is closely adjacent the said members.

30. A readily removable and interchangeable heating device unit for an automatic circuit breaker comprising in combination two adjacent conducting connection members spaced apart and adapted for mechanical and electrical connection with attachment terminals, a transverse insulating member connecting the two connection members and serving as a handle for the device, and a U-shaped current-carrying heating element having the end portions of its legs electrically and mechanically connected with the said connection `members and' having the outer portions thereof extending backward in approximate parallelism with the said end portions so that the transverse portion of the U isV closely adjacent the said members.

31. A readily removable and interchangeable heating device unit for an automatic circuit breaker comprising in combinattion two adjacent conducting connection members spaced apart and adapted for mechanical and electrical connection with attachment terminals, a U-shaped currentcarrying heating element having the end portions .the U is closely adjacent the said members, andtwo supports extending longitudinally from the connection members between the said portions of the respective legs ofthe U.

Josmn scns.

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