US2134565A

US2134565A - Circuit breaker

Info

Publication number: US2134565A
Application number: US104842A
Authority: US
Inventors: Merrill G Leonard
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1936-10-09
Filing date: 1936-10-09
Publication date: 1938-10-25
Anticipated expiration: 1955-10-25
Also published as: DE696413C

Description

0a. 25, 1938. M, LE NARD 2,134,565

CIRCUIT BREAKER Filed Oct. 9, 1936 X 322% L mflimfig? 7/ Way ?9 92 Z2 WITNESSES: INVENTOR Patented Oct. 25, 19538 PA NT OFFICE CIRCUIT BREAKER Merrill G. Leonard, Sharon, Pa", assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa,

Pennsylvania Application October 9,

21 Claims My invention relates "to apparatus for interruptlug electrical circuits, in general, and more particularly to circuit breaker structures of the protective which include one or more electro-responsive trip devices for automatically eirectirig opening of the contact means or the circuit breaker in response to predetermined overload conditions in the circuits controlled by the breaker.

in circrdt breakers of the above mentioned type, the electric-responsive device for efiecting opening of the contact means in response to overload conditions usually consists of an electromagrietic or bimetallic device or both, connected series circuit with the contact means oi the breaker so as to be responsive to pre iiiC-Elifilfi'llllifi values of current flowing in the circuit controlled by the breaker. When such circuit breakers are installed for use in electri= Ell cal systems, they are often called upon to interrupt circuits including highly inductive loads and often subjected to heavy overloads or to short circuit conditions. in opening a circuit breaker under such conditions, it is well known that current continues to flow tlierethrough ior appreciable length of time after sep-= aratioii oi the contacts due to the formation and persistence of an are at the contacts. Arc extinguishing devices are usually provided for extinguishing the are thus formed as quickly as possible. in spite of the provision of such devices, however, the current continues to flow for a length oi time sufficient in many instances to damage or destroy the trip devices of the breaker.

It is, therefore, the primary purpose of my invention to provide circuit breakers of the above-mentioned type with a means for protecting the electro-responsive trip device or devices from are currents.

Another object of my inventlon is to provide a means for excluding the clectroqesponsive. trip device of the circuit breaker from the circuit of the arcand contacts as soon as the contacts start to open.

Another object oi my invention is to provide a circuit breaker with novel internal circuit connectlons for protecting the trip device of the breaker Irom excessive currents.

Another object of my invention is to provide a circuit breaker having an arc extinguishing means with novel internal circuit connections including a part of said are extinguishing means for excluding the trip device of the breaker from a corporation; of

1936, Serial'l lo. HD4342 (Cl. 2llll===llllt l the circuit oi the are upon initial separating movement of the contacts.

Another object of my invention is to provide a circuit breaker with'rneans for protecting the trip device thereof by immediately transferring 5 *the arc circuit formed incident to the separa tion of the contacts to an auxiliary contact not included in the circuit of the trip device.

Another object of my invention is to provide a means for protecting the tripdevice of a circult breaker by transferring the arc circuit formed incident to separation of the main contacts to an auxiliary contact not included in the circuit of the trip device; in which the auxiliary contact constitutes a part of the arc extinguishing means.

The novel features that i consider characteristic of my invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operatlon, together with additional objects and advantages thereof, will best be understood. from the following detailed description, of specific embodiments thereof when read in connection with the accompanying drawing, in which:

Figure l is a vertical sectional view of a cirbrealrer embodying the features of my invention,

Fig. ,2 is a diagrammatic view illustrating. one form of electrical connections for the various elements of the breaker for carrying out the purposes of my invention,

Fig. 3 is a diagrammatic view similar to Fig. 2 illustrating a slightly modified form of apparatus and electrical connections for carrying out the purposes of my invention; and, 35

Fig. 4 is a plan view of the arc extinguishing device associated with the contacts of the circuit breaker.

In the accompanying drawing, the invention has been shown applied to one particular form of circuit breaker structure embodying an electro-responsive trip device and an arc extinguishlng means of the spaced plate type. The particular circuit breaker structure shown was selected for illustrative purposes only and it will readily appear from the following detailed description that the invention is not limited in its application to any one particular circuit breaker structure but thatit is capable of association with any form of circuit interrupting device embody- 50.

mg an eleotro-responsive trip device and an arc extinguishing device.

The circuit breaker illustrated in Fig. 1 is of the same general'mechanical structure as disclosed in the United States Patent No. 2.044.157, 5o

granted to H. D. Doriman and John H. Shuler and assigned to the assignee of this invention; hence only a brief description of the same will be given in this application. 5 Referring to Fig. 1, the base I of the circuit breaker is of molded insulating material and has mounted in recesses provided therein the end terminals 9 and H, a main stationary contact l3, a. movable contact- IS, the circuit breaker operating mechanism indicated generally at H, an electro-responsive trip device I9 and an arc extinguishing means indicated generally at 2|. An operating handle 23 also of molded insulating material is provided for actuating the operating mechanism ii. The trip device is is supported on the base i and positioned with respect to the operating mechanism by means of two suitable screws 25 (only the front screw being shown) which engage threaded inserts 25 molded in the base i. These screws also serve to connect the trip device in the internal circuit of the breaker which will be described hereinafter. The are extinguishing means and the operating mechanism are secured to the base in any suitable manner as for example by the screws 21 which extend through suitable openings therein. A cover 29 of molded insulating material is removably mounted on the base by means of bolts (not shown).

The main stationary contact I3 is mounted on a metallic plate 3! which will hereinafter be termed an arc runner. The are runner is secured to the base by any suitable means such as one of the screws 21.

Both the movable and stationary contacts are constructed of arc resisting material, the former being composed of a silver molybdenum alloy and the latter being composed of finely divided silver. and graphite compressed into a conglomerate mass. The are runner 3| may also be constructed of an arc resisting conducting material similar to the stationary contact l3.

The movable contact |5 has a channel shaped frame 33 which is pivotally supported on a U 45 shaped main frame 35 of the circuit breaker operating mechanism ll through the agency of a pivot pin 3'1. The movable contact I5 is rigidly afiixed by means of a rivet to the free end of a resilient switch arm 39 which is preferably constructed of spring steel. The switch arm itself is affixed to the channel shaped frame 33 by means of two other rivets.

The operating mechanism comprises in genera], the U shaped base or main frame 35, a pair of toggle links 4| and 43 for actuating the channel shaped frame 33 of the movable contact IS, a releasable trigger 45 for restraining the toggle links in an operative position, an operating member 23, and a pair of overcenter springs 41 (only one being shown) for connecting the operating member to the knee pivot of the toggle links 4| and 43. The operating member 23 has a bifurcated portion 49, the legs of which are pivotally mounted on the sides of the main frame 6535 through the agency of pivot pins 5|. The releasable trigger 45 is pivotally mounted at one end to the sides of the main frame 35 by means of a pivot pin 53 and has projecting portion 54 adapted to be normally engaged and held by the trip device IS. The operating member 23 has a hook portion 55 secured to the underside thereof which is adapted to engage a shoulder 51 formed on the trigger 45 for resetting the trigger after the release of the same by the trip device. The lower end of the toggle link 4| is pivoted to the grasses channel shaped frame 33 by means of a pivot pin 55. The upper end of the toggle link 4| is pivotally connected by means of the knee pivot pin 6| with the lower end of the toggle link 43, the upper end of which is, in turn, pivotally connected to the trigger member 45 through the agency of a pin 53. The overcenter springs 41. have their lower ends connected to the knee pivot pin GI and their upper ends secured to lugs 64 formed on the underside of the bight of the bifurcated portion 49 of the operating member 23. The trigger 45 provides a releasable restraining means for holding the toggle links in an operative position when the contacts l3 and I5 are engaged.

The movement of the trigger member 45 in a clockwise direction is limited by a projection 85 which extends inwardly from one side of the main frame 35. The limits of motion of the bifurcated portion 49 of the operating member 23 are defined by the edges 61 of onset portions of the side walls of the main frame 35. A handle portion of the operating member 23 projects through a slot 69 provided in the cover 29.

The trip device l9 comprises a U shaped current carrying bimetallic trip element 1|. A latch plate 13 is mechanically fastened to the upper end of the trip element l9 and insulated therefrom by means of mica plates 15, the latch plate being held in position by two spaced rivets 11 (only one being shown) which extend through a retaining plate 19 and enlarged openings in the top portion of the bimetallic trip element itself. The trip element is supported upon its own terminals 80 (only one being shown) through the agency of rivets 18. The projecting portion 54 of the trigger 45 is normally adapted to be engaged under the lower edge of the latch plate I3 between the rivets 11.

The are extinguishing means 2| consists of a plurality of spaced plates ill of magnetic material each insulated from the adjacent plates and provided with a slot 83. The slots in the plates are of substantially the same outline as the movable contact l5 and the position of the plates is such that the slots form a path adapted to be traversed by the movable contact IS in moving into and out of engagement with the stationary contact I3. The plates 8| are assembled between two side walls 85 of insulating material. Projecting lugs 81 are provided on the plates II for engagement in openings in the side walls 55.

when the movable contact l5 moves away from its engagement with the stationary contact, toward open circuit position, an arc is drawn which creates a magnetic field surrounding the path of the arc. The magnetic plates 8| so unbalance the field adjacent the are that the arc is moved into the spaces between the plates where it is quickly cooled and extinguished. The plates cause the arc to be immediately transferred from the stationary contact l3 to the arc runner 3| thus protecting the stationary contact from damage by contact with the arc. The are is split up into a series of short arcs between the adjacent plates 8|, the first short are being immediately established between the arc runner 3| and the bottom plate of the stack.

The operation of the circuit breaker will now be briefly described. In Fig. 1, the breaker is shown in the open circuit position with the trigger or restraining member 45 in the set or latched position in which it is held by the latch plate 13 of the trip element 1 I. The toggle links 4|-43 are in their collapsed position. It will be noted that the trigger 45 is at all times biased in a clockwise direction by the reactionforce of the overcenter springs fil. Let it be assumed that it is desired to manually close the circuit breaker. The operating member 23 is moved from the position shown in a clockwise direction about its pivot pin 51%. Shortly before the operating member has reached the limit of its travel in a clockwise direction, the line of action of the over-= center springs t'l is brought to the right of the center line of the toggle. This results in producing a force which automatically moves the toggle links with increasing acceleration to their overset position which effects movement of the movable contact it to the closed circuit position with a snap action. To open the contacts, the operating member 23 is moved from its closed circuit position in a counter-clockwise direction about its pivot pin M to its open circuit position shown in Fig. 1. Substantially the reverse action takes place. The line of action of the over center springs is moved to the left of the center line of the toggle which produces a force which automatically moves the toggle links with increasing acceleration to their collapsed position shown in Fig. l. The collapsing of the toggle causes movement of the movable contact to'its open circuit position with a snapaction.

The bimetallic trip element ii is adapted to be connected in series circuit with the contacts of the breaker as will be described hereinafter. W h the circuit breaker in the closed circuit position; upon the occurrence of an overload contion of predetermined magnitude, the increased 3. loss the bimetallic trip element results in the oroduction of sufilcient heat to cause that eie= :ineut deflect in a direction away from the op crating mechanism i 27. if the overload persists for a s" cient length of time, this deflection be comes great enough to move the latch plate 'ching engagement with the projecting the trigger This unlatching oi it allows that member to rotate in a e direction about its pivot under luence oi the reaction forces of the overcenter springs ll. almost immediately the up p of the toggle linlr :33 which pivoted to he ger by the pin is moved a "S ncient distance to the right of the center line of to le to cause the toggle to collapse vile innuenceol overcenter ll ex erting their tension on the knee oivot pin ill. The channel shaped frame is rotated about its pivot by the collapse of the toggle, thus the movable contact ill to its open circuit position with a snap action the same manner as desciihed for the manual operation,

Following the tripping operation and the re sulting change-in position of the lrnee pivot pin the operating handle 23 is biased in a counter-clockwise direction but moves only to a micl-position in the slot B9 of the cover 29. This movement of the handle 23 to the mid-nosition following the tripping operation serves as a ready indicating means for showing that the circuit has been openedin response to an abnormal electrical condition.

The entire mechanism is resettable after a trip-= ping operation by movement of the operating member 23 to the full open circuit position as soon as the bimetallic trip element, 'II has cooled sufflciently to restore the latch plate 13 to the position shown in Fig. 1 This movement causes the hook portion 55 of the operating member to engage and move the trigger member 45 in a counter-clockwise direction until its projecting portion 54 reengages under the latchplate 13. The breaker may then be closed manuallyin the manner previously described.

The operating mechanism I1 is trip tree of the operating member 23 in any position of the parts, i. e., the movable contact l5 may be tripped to the open circuit position irrespective of the position of the operating member 23.

It'has been the practice in most circuit breakers of the above-mentioned type to connect the electro-responsive trip device or bimetallic trip element in series circuit relationship with the contact means of the breaker in order that the device may respond to overload conditions. 'When' the breaker having the above nientioned connection is manually operated to open a cir cuit including a highly inductive load, or when it is automatically opened in response to an altnormally large overload or short circuit condi tion, the persistence of the are after the separation of the contacts may'result in damage or'de struction of the trip device with the resulting loss of the safety feature in subsequent overloads.

The means for protecting the electro-responsive trip device from the damage indicated above will now be described.

The electro-responsive trip device or the hi nietal tripelelnent the present disclosure is protected from abnormal current conditions by means of novel internal circuit connections for connecting the trip device in a certain circuit relationship with the terminals, contact means and a part of the are extinguishing means. In one form of the invention, the connections are made as follows: Referring to 2, a condoctor connects the load terminal to the rear terminal of the bimetallic trio element 'Jl. The forward terminal of the trip element '0 i is connected direct y to the are runner 3i and sta tionary contmt 5-3 by means of an insulated condoctor The movable contact is connected through the agency of the switch arm 539 with an insulated conductor which is, in connected to the line terminal it of the circuit breaker. The conductor is electrically con nected to the'line terminal all by means of the terminal connec sciew 9 (face Fig. l.) will be noted that the connections described shove golace the o netallic trio element ll in series circuit relationship with the stationary con tact it, the movable contact (I and the end terminals 9 and ill of the circuit breaker when the contacts are closed. The insulated shunt conductor connects the terminal to the bimetallic trip element ll with the bottom plate til oi the arc extinguishing means The conductors 9i and are connected to the terminals of the bimetallic trip elen'lent through the agency of the screws 25. The insulated condoctor Ell is connected to the stationary contact 53 and are runner ill through the agency of a screw 92 (see Fig. l) A recess til is provided in the base l of the circuit breaker for receiving the insulated conductor wires M, 93 and 95 (see Fig. l). The operation of the breaker with the form of connections described above is as follows:

With the contacts in the closed circuit position,

- the'circuit through the breaker extends from the line terminal ll through the conductor 93, the

switch arm 39, movable contact l5, stationary contact l3, insulated conductor 9|, the front ter' mine! so of-the bimetallic trip element ii, the

load terminal a. If the movable contact I5 is moved toward open circuit position either in response to operation of the operating member 2a or in response to a tripping operation by means of the bimetallic element 11,. an arc is formed between the contact 53 and the movable contact i". The are is immediately transferred from the stationary contact i3 t the arc runner 36 by the unbalanced magnetic field caused by the plates 8t. As has been previously described, the arc is split up into a series of short arcs extending between the plates 8! and between the bottom plate 8i and the arc runner 3!. The short are between the arc runner 3i and the bottom plate of the stack is sustained only by the voltage drop across the bimetallic trip element it This voltage is so low that the short arc between the bottom plate 8% and the arc runner St is immediately extinguished, thus excluding the bimetallic trip element from the circuit of the remaining are or arcs. The arc circuit then em tends from the load terminal 9 through the con ductor to the bottom plate 8! of the stack though the arc in the space between the plates to the movable contact l and through the condoctor 98 to he line terminal 5 i. It will thus be seen that t "metallic trip element is excluded from the are t or" the arcs as soon as the movable contact moves a suificieht distance to establish are e 'her between the stationary contact and t e bottom plate or between the arc runne: and the bottom plate of the extinguishing means. Hence the arc current can have no dam effect on the bimetallic trip element. the voltage d op across bimetallic rip e too more than one of the plates could included berunner and the iii-metal connector e invention are shown in in lg. the arc is divided into e or 535?. The insulated conductor -nected to back of bimetallic trip element '55 instead of being cc Elected to the bottom magnetic plate 2% as in 2, is connected to the end section B2 of the are runner. All of he other electrical connections and elements are the same as the corresponding connections and elements shown in Figs. 1 and 2: The operation of this modified form of apparatus and circuit is similar in principle to the embodiment shown in Figs. 1 and 2. When the movable contact is in the closed circuit position, the electro-rosponsive trip device or bimetallic trip element is connected in series circuit relationship with the contacts i3 and i5 through the following circuit: Line terminal H, insulated conductor switch arm 39, movable contact i5, stationary contact i3, insulated conductor 3!, olrnetallic trip element H, conductor 39 and load terminal As soon as the movable contact starts to move to the open circuit position either in response to a manual or a tripping operation, the are formed at the contacts is transferred to the extreme end section 32 of the arc runner by the unbalanced magnetic field produced by the plates at. The end section 32 of the arc runner constitutes, in effect, an auxiliary contact to which the arc is transferred as soon as the movable contact starts to move to the open circuit position. As soon as the arc is transferred to the end section 32 of the arc runner, the electroresponsive trip device or bimetallic trip element H is excluded from the circuit of the are by means of the insulated shunt conductor 95. The are circuit then extends from the load terminal 9 through conductor 89 and the insulated shunt conductor 95 to the end section 32 of the arc runner, through the stack of plates, the movable contact I5, through the switch arm 39 and the insulated conductor 93 to the line terminal II.

It will be noted that in the embodiment shown by Figs. 1 and 2, the bottom magnetic plate of the arc extinguishing means constitutes, in effect, an auxiliary contact to which the arc is transferred upon initial movement of the movable contact toward its open circuit position.

An important feature of the invention lies in the fact that the current-responsive element is shunted out of the circuit as soon as the moving contact has moved only a short distance and before it has moved to the full open position. This removes the current-responsive element from the circuit before it has time to heat up and burn out. It is also advantageous that the circuit of my device does not require a connection to the top arc extinguishing plate which would impress line voltage across the arc extinguisher even when the circuit is open and would permit a leakage current to flow if the fibre side plates of the arc extinguisher should become damp or carbonized.

While the invention has been shown associated with a particular form of circuit breaker, it is obvious that the invention is equally applicable to any form of circuit interrupting device which includes an electro-responsive trip device and an arc extinguishing means or are moving means, For example, the various forms of electro-respon sive trip devices may be substituted for the U- shaped bimetallic trip element illustrated. The trip device may be either in the form of a therfinally responsive device or in the form of an electromagnetic trip device. Likewise, various other forms of arc extinguishing devices may be used. The are extinguishing means illustrated is merely selected for simplicity to illustrate the principle of the invention. One particularly effective form of arc extinguishing means to which the invention applicable is disclosed in the United States Patent No. 1,963,643 granted to Benjamin P. Baker and Maurice W. Brainard, and assigned to the assignee of this invention.

It will thus be seen that I have provided a novel means associated with a circuit interrupting device oi the protective type for protecting the electro-responsive trip device thereof from damage by the arc current.

While in accordance with the provisions of the patent statutes, I have disclosed the foregoing details of several embodiments of my invention, it is to be understood that many of the details are merely illustrative and that variations, in addition to those mentioned, in their precise form may be made without departing from the spirit of the invention. l desire. therefore that the language of the accompanying claims shall be accorded the broadest reasonable construction. and that my invention be limited only by what is explicitly stated in the claims and by the prior art.

I claim as my invention:

1. A circuit interrupting device comprising switch contacts. electro-rcsponsivc means or efi'ecting separation of said contacts connected in circuit therewith, arcing plates to which the are between the contacts is transferred, and means for shunting the arc current around said electrotill responsive means and one of said contacts to one of said arcing plates upon initial opening movement of said switch contacts.

2. A circuit interrupting device comprising switch contacts, electro-responsive means for effecting separation oi said contacts connected in circuit therewith, arcing plates, means including said plates for efiecting transfer of the are from said contacts to said plates and connections rendered operable by transfer of the are for ex= eluding said electro-responsive device from the circuit of the are as soon as said contacts have separated a small part of their total distance of separation.

circuit hreaker comprising a stationary contact, a movable contact, electro-responsive means for efiecting movement of the movable contact to open circuit position connected in circult with said contacts, means including a series of spaced plates of magnetic material for trans ierring the are formed incident to the opening oi the contacts from the contacts to said plates and for extinguishing the same, and a connec tion completed by the are for excluding said elec= tro-responsive device from the circuit of the arc during the first part of the movement of said movable contact toward open circuit position.

Acircuit breaker comprising switch con tacts, electrwresponsive means connected in clrcult with said contacts for effecting opening oi contacts in response to predetermined conditions, means including a series of spaced plates of magnetic material for effecting transfer of the are formed incident to the opening of said con tacts from the contacts to said plates, and means operable by transfer of the are for excluding the electrc-responsive device from the circuit oi the are upon the initial opening movement oi said contacts,

circuit breaker the combination of a stationary contact, a movable contact, an electro a .t of the movable cont-act to the open circuit position in response to] predetermined conditions, an arc extinguishing device comprising an are ill connected to the stationary contact and a alits/ oi spaced notched plates or" magnetic material for transferring are formed incilt to theopening oithe contacts from said contacts to said are runner said plates, a connection from said electro-o'esponsive device to one of said plates nearest said stationary contact i'cr excluding said electro-responsive device the circuit of the are as soon as said inov== aisle contact has moved a small part of its total movement to the open circuit position.

A circuit interrupting device comprising a fused and a movable contact between which an arc is drawn, an electro-responsive device con-= nected circuit with said contacts for effecting movement of the movable contact to open circuit position inresponse to a predetermined magnitude of current, means including a plurality oi arcing plates of magnetic material for efiecting transfer of the are from said contacts to said plates, and a connection from said electro-re-= sponsive device to one of said plates for excluding said device from the circuit of the are upon initial movement of said movable contact toward opencircuit position.

'7. A circuit breakcr comprising a stationary and a movable contact between which an arc is drawn, an electro-responsive device connected in circuit with said contacts for effecting movement of the movable contact to the open circuit position in response to a predetermined condition, an auxiliary contact, means for excluding said device from the circuit of the arc and for transferring the arc to said auxiliary contact upon initial movement of said movable contact toward open circuit position.

8. A circuit breaker comprising a stationary contact and a movable contact between which an arc'is drawn, an electroresponsive trip device connected in the circuit leading to the stationary contact for efiecting opening of said contacts, an arc extinguishing means including a series of spaced notched plates of magnetic material for transferring the are from said contacts to said plates and a connection for excluding said device and said stationary contact from the circuit of the are upon movement 0:? the movable contact toward open circuit position.

9. In a circuit breaker the combination of switch contacts, electroc-responsive means connected in circuit with said contacts for effecting separation of said contacts in response to predetermined conditions and means for excluding the electro-responsive, device from the circuit of the are formed incident to separation of the contacts, said means being operable in response to the initial separating movement of the contacts.

iii. in a circuit breaker the combination of switch contacts, a thermal bimetallic device in circuit with said contacts for effecting separation or said contacts in response to predetermined conditions, and means for excluding the thermal bimetallic device from the circuit of the are formed incident to the separation of said con tacts, said means losing operable in response to the separation of said contacts and as soon as said contacts have separated a small part of their total distance of separation.

ii. In a circuit breaker the comhination of line and load terminals, a stationary contact, a movable contact connected to said line terminal, an electro-responsive device having one terminal thereof connected to the load terminal and its other terminal. connected to said stationary contact for effecting movement of the movable contact to open circuit position in response to pre determined conditions, an arc extinguishing means comprising an runner connected to said stationary contact and a series of notched spaced plates oi magnetic material for efiecting transfer of the are formed incident to separation of the contacts from the stationary contact to said are runner and said plates and a connection completed by the transfer of the arc to said are runner for excluding said electro-respcnsive device from the circuit of the are as soon as the movable contact has moved a small part or" its total movement toward open circuit position.

12. In a circuit breaker the combination of line and load terminals, a stationary contact, a movable contact connected to said line terminal, an electro-responsive device having one terminal thereof connected to the load terminal and its other terminal connected to said stationary contact for shooting movement of the movable contact to open circuit position in response to predetermined conditions, an arc extinguishing means comprising an arc runner connected'to said staof said plates for excluding said device from the circuit or" the are upon initial movement of said movable contact toward open circuit position.

13. In a circuit breaker the combination or line and load terminals, a stationary contact, a movable contact connected to one of said terminals, an electro-responsive device having one terminal thereof connected to the other terminal and its other terminal connected to said stationary contact for effecting movement of the movable contact to open circuit position in response to predetermin d conditions, an arc extinguishing means comprising an arc runner connected to said stationary contact and series of notched spaced plates of magnetic material for effecting transfer of the are formed incident to separation of the contacts from the stationary contact to said arc runner and said plates and a conductor connecting the first mentioned terminal of said device to the plate nearest arc runner for excluding said device from the circuit of the arc as soon as said movable contact has moved a smal part or" its total novernent toward open circuit position.

In circuit breaker the combination of line and load terminals, a stationary contact, a movable contact co nected to line terminal, a bimetallic device having one terminal thereof connected to the terminal and its other terminal connector. to said stationary contact for effecting movement of the movable contact to open circint position in response to predetermined guishin: mews comprisan arc runner contact series r magnetic transfer of the are formed incident to separation of the contacts from static; *7 contact to said are runner and said plates connection for excluding It oi the ma]. movement toward open circuit pospaced plates 15. .L. c cin't combination contacts, a device circuit g separation of .eterz. 'ned concircuit completed the separation of the contacts e2" losing the bimetallic device from the circuit me are as soon as said contacts have separated a small part ct their total distance of separation.

in a circuit breaker combination of line and load term'nals, a movable contact con.- nected to the line tc.minal, a stationary contact, an electro-responsive means having one terminal connected to the. load terminal and its other terminal connecte to said stationary contact for eiiecting movement of said movable contact to open circuit position in response to predetermined condition, an arc extinguishing device comprising a divided arc runner having one section thereof connected to the stationary contact, the other section thereof insulated therefrom, a plurality o notched spaced plates of magnetic material for effecting transfer of the are formed incident to separation of the contacts from said stationary contact to the insulated section of the arc runner and to said plates, and a connection from first mentioned terminal oi said electro-responsive so to said insulated section of the arc runner for excluding said electroresponsive means from the circuit of the are upon initial movement of said movable contact toward open circuit position.

17. In a circuit breaker the combination of line and load terminals, a. movable contact connected to the line terminal, a stationary contact, a bimetallic means having one terminal connected to the load terminal and its other terminal connected to said stationary contact for eflectlng movement of said movable contact to open circuit position in response to predetermined condition, an arc extinguishing device comprising a divided arc runner having one section thereof connected to the stationary contact, the other section thereof insulated therefrom, o. plurality of notched spaced plates of magnetic material for effecting transfer of the are formed incident to separation of the contacts from said stationary contact to the insulated section of the arc runner and to said plates, and a connection from the first mentioned terminal of said bimetallic means to said insulated section of the arc runner for excluding said means from.the circuit of the are as soon as said movable contact has moved a. small part of its total movement toward open circuit position.

18. In a circuit breaker the combination of a stationary contact, a movable contact, an electroresponsive device normally connected in circuit with said contacts for efiecting movement of the movable contact to open circuit position in rc spouse to predetermined overload conditions, an auxiliary conducting member to which the end of the are established on the stationary contact is transferable means i or excluding said electro responsive device m th circuit the are upon transfer of the end of he s c from t re stationary contact to conducting member.

a circuit breaker the combination of a stationary contact, movable contact, a. bimetallic device connected oil with he stationary contact for efiecl overnent of the movable contact to open response to predetermined transferring the tion of the contactfluent to separa sm d stationary contact to an auxiliary c "tact and a conductor connected to said coo. act for excluding said device from the circuit of the are immediately after said movable contact has oved a small distance toward open circuit position.

20. In a circuit interrupter, he combination of a stationary contact, a moval is contact, an electro-responsive device normally connected in circuit with said contacts, a plurality of conducting members into which the are drawn between said contacts is movable, and one 01 said conducting members nearest said stationary contact being connected to provide a shunt circuit around said electro-responsive element upon contact of theme therewit 21. In a circuit breaker the combination of switch contacts, electro responsive trip means connected in circuit with said contacts for effecting separation of said contacts in response to predetermined conditions, and means including an electrical connection completed by the are formed incident to the separation 01' said contacts for excluding the electro-responsive means from the circuit of the are upon initial separating movement of the contacts.

' MERRIIL G. LEONARD.