US2719203A - Circuit breakers - Google Patents

Description

Sept. 27, 1955 WITNESSES:

F. L. GELZHEISER ET AL CIRCUIT BREAKERS Filed May 2, 1952 INVENTORS Stephen S. Dobrosielski.

Francis L. Gelzheiser 8 United States Patent crncurr BREAKERS Francis L. Gelzheiser, Pittsburgh, and Stephen 5. Dohrosielski, Beaver, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 2, 1952, Serial No. 285,696

13 Claims. (Cl. 2062-144) This invention relates to circuit interrupters and, more particularly, to are extinguishers and venting arrangements for facilitating the rupture of arcs drawn between the cooperating contacts and the expulsion of the hot arc gases from such circuit interrupters.

An object of the invention is to provide a circuit breaker with an improved arc extinguisher for facilitating the rupture of arcs drawn between the cooperating contacts of the circuit breaker.

Another object of the invention is to provide a circuit breaker having an improved arc extinguisher structure for facilitating the rupture of the are drawn between the separating contacts and a circuit breaker housing forming a passageway for facilitating the safe expulsion of hot arc gases from the end of the breaker housing opposite to the separating contacts.

An additional object of the invention is to provide a small compact circuit breaker of adequate dielectric strength across the surfaces of the breaker housing, without spraying the surfaces with a composition to prevent them from becoming carbonized by the hot arc gases.

A further object of the invention is to provide an improved circuit breaker of small size capable of safely interrupting overload currents of large magnitude which is inexpensive in construction and dependable in operation.

The invention, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of an embodiment thereof, when read in conjunction with the accompanying drawing.

In the drawing:

Figure 1 is a side elevational view with the cover removed of a circuit breaker embodying the principles of the invention.

Fig. 2 is a vertical sectional view taken on line IIII of Fig. 1 through the arc extinguisher.

Fig. 3 is a reduced elevational view of the inside of the cover showing the recesses and surfaces for receiving and supporting the parts of the circuit breaker.

Fig. 4 is an exploded perspective view showing the main body of the arc extinguisher, the cover for the arc extinguisher, the plug-in contact member and the arc runner.

Referring to Fig. l of the drawing, the circuit breaker comprises generally an enclosing casing including a base or housing member 11 and a cover or cooperating housing section 13 (Fig. 3) both made of molded insulating material, a stationary contact 15, a movable contact 17, an operating mechanism 19, a trip device 21 and an arc extinguisher 25.

The stationary contact is rigidly secured to the inner end of a conducting member 22 integral with a plug-in connector member 23 supported in the housing 11 and in the cover 13 as will be more fully described later. At the opposite end of the housing 11 is disposed a conducting strip 29 which at its inner end is connected to the trip device 21 and which is provided with a terminal connect- Z,?l9,2ll3 Patented Sept. 27, 1955 ing means, such as a screw 31, at its outer end for connecting the breaker in an electric circuit.

The movable contact is rigidly secured on the free end of a U-shaped switch arm 37 having its legs 57 supported in recesses in the legs 55 of a U-shaped operating lever of molded insulating material. The operating lever 35 is pivotally supported by trunnions 36 molded integral therewith and mounted in suitable companion openings in the housing member 11 and in the cover 13. An overcenter operating spring 39 is connected under tension between the bight of the switch member 37 and a releasable carrier 33 pivoted on a pin 41 supported in the housing Ill and in the cover 13.

The operating lever 35 is provided with a handle 49 molded integral therewith and extending outwardly through an opening 51 in the housing 11. The operating lever 35 is also provided with an arcuate portion 53 cooperating with the housing 11 to substantially close the opening 51 in all positions of the operating lever. The switch member 37 is electrically connected by a flexible conductor 59 to one end of a bimetal element forming part of the trip device 21 which is suitably secured to and supported by the inner end of the conducting strip 29.

The switch arm 37 is operated to manually open and close the contacts by operation of the lever 35 which is eflected by manipulation of the handle 49. Movement of the handle 49 in a clockwise direction carries the pivoted ends of the legs 57 of the switch member 37 across to the left of the line of action of the operating spring 39 which then biases the switch member to the open position and causes movement of the switch members to the open position with a snap action.

The contacts are manually closed by reverse movement of the operating lever 35. Counterclockwise movement of the lever 35 from the open position to the closed position moves the upper pivoted ends of the legs of the switch member 37 across to the right of the line of action of the spring 39 which thus acts to close the contacts with a snap action.

The circuit breaker is tripped open after a time delay in response to overload currents below a predetermined value and instantaneously in response to overload currents above the predetermined value, or in response to a short-circuit current, by means of the trip device 21, which will be hereinafter described in detail. Operation of the trip device 21 causes release of the carrier 33 whereupon the operating spring 39 moves the carrier 33 clockwise about its pivot 41. This moves the line of action of the spring 39 across to the right of the center line of the switch arm 37 and the spring 39 then acts to move the switch arm to the open position with a snap action. The movement of the carrier 33 is arrested by engagement with a projection or wall portion 61 molded integral with the housing parts 11 and 13.

The trip device comprises the bimetal element 45 connected by the flexible conductor 59 to the movable switch arm 37 and electromagnetic means including a magnetic member or armature 63 mounted on the bimetal element 45 and an H-shaped magnetic member or magnet yoke 65 supported in a recess 69 in the housing and a companion recess 70 in the cover 13 (Fig. 3). The conducting strip 29 is secured to the adjacent end wall of the housing 11 by ascrew 71 and the bimetal 45 is rigidly secured by suitable means such as welding to the upper inner end of the conducting strip 29 and extends downwardly therefrom.

The magnetic member 63 is rigidly secured to the bimetal element 45 by an enameled rivet 73 which also rigidly fastens a latch member 67 to the bimetal element. The latch member 67 normally engages and releasably restrains the carrier 33 in operative position. The latch member 67 is insulated from the bimetal element 45 and from the armature 63 by the sheets of insulating material (not shown) and by the rivet 733 which is formed from a section of wire precoated with an insulating enamel.

The recesses 69 (Fig. l) and 70 (Fig. 3) in which the legs of the magnet yoke 65 are disposed are provided respectively with shoulders 75 and 77 against which the magnet yoke 65 is biased by a light compression spring 79 to provide a normal air gap between the magnet yoke 65 and the armature 63. The spring 79 is compressed between the adjacent end wall of the housing 11 and the magnet yoke 65 and is held in place by cooperating with a spring seat 81 formed on the magnet yoke 65. The spring seat 81 may be formed by any suitable method such as, for instance, embossing which also provides a recess 83 on the opposite side of the magnet yoke 65 which serves as a clearance for the head of the rivet '73. The recesses 69 and 70 (Figs. 1 and 3), in which the legs of the H-shaped magnet yoke are disposed, are wider at the bottom than they are at the top to permit pivotal movement of the magnet yoke in the direction of thermal bending of the bimetal element 45. This arrangement permits maximum deflection of the bimetal element when it is hot and prevents it from taking a permanent set as it would if its deflection were opposed by any substantial forces such as by engaging a fixed magnet yoke.

Means is provided for calibrating the trip device. This means comprises a screw 85 threaded through a nut 87 disposed in a recess 89 in the adjacent end wall of the housing 11. The inner end of the screw 85 engages the upper end of the conductor strip 29 on which the bimetal element 45 is mounted. An access opening 91 is provided through which the screw may be rotated to adjust the trip device after which the opening 91 may be sealed to prevent tampering. Turning the screw 85 causes bending of the conductor 29 and corresponding variation of the position of the bimetal element according to the direction in which the screw is rotated to thereby vary the tripping point of the breaker.

Upon the occurrence of a low persistent overload current below a predetermined value of, for instance, ten times normal rated current, the bimetal element 45 is heated and bends toward the right causing release of the releasable carrier 33. The releasable carrier 33 causes movement of the switch member 37 to the open contact position in the manner previously described.

When an overload current above ten times normal rated current or a short circuit current occurs, the electromagnetic trip means is energized and the armature 63 is attracted toward the magnet yoke bending the bimetal element 45 and causing the latch member 67 to instantaneously release the releasable carrier 33 and open the contacts. The specific thermal-magnetic tripping arrangement disclosed herein is being claimed in the copending application Serial No. 285,598, filed May 2, 1952, by L. W. Dyer, now Patent No. 2,677,025, issued April 27, 1954, and assigned to the assignee of this application.

The releasable carrier 33 is reset and relatched and the contacts closed following an automatic operation by first moving the handle 49 clockwise to the off 'position and then counterclockwise to the on position. When the handle is moved to the off position, the legs 55 of the operating lever 35 engage a pin in the carrier 33 and move the carrier counterclockwise about its pivot 41. Near the end of this movement, the free or latching end of the carrier 33 wipes by the latch 67, slightly bending the bimetal element'which then resumes its normal latching position.

An important feature of the invention is the novel are extinguisher indicated generally at 25 and the arrangement for venting the hot gases in substantially a straight line to atmosphere at the end of the housing opposite the separating contacts 1517.

The arc extinguisher consists of a plurality of spaced arc splitting plates 95 of magnetic material shaped as more clearly shown in Figs. 2 and 4. Each plate 95 has a slot 97 formed thereon and is provided with a plurality of lugs 99 whereby the plates are rigidly attached at the sides of a U-shaped supporting and insulating housing or enclosure 101 composed of a relatively rigid fibrous cellulosic material. The sides of the housing 101 are pro vided with openings for receiving the lugs 99 which are riveted over to rigidly support the plates in the housing. The are extinguisher is disposed in the housing and is supported between the projection 61 on the housing and a corresponding projection 61a (Fig. 3) molded in the cover plate 13, and corresponding surfaces 103 on the housing and 103a on the cover 13.

A cover 105 (Figs. 1, 2 and 4) of insulating material such as fibre is provided for the arc extinguisher and has a U-shaped slot therein for receiving the lower end of the movable switch member 37. The cover 105 is held in place by openings 107 therein engaging projections 109 on the upper edges of the housing 101, and by the edges of the cover fitting into corresponding slots 111 and 113 formed respectively in the breaker housing 11 and in the cover plate 13. The left-hand end of the arc chute cover 105 has an extension 115 thereon extending upwardly at an angle between the conducting member 22 and similar projections 117 and 117a on the breaker housing and cover respectively, the extension 115 projecting into a slight recess 119 formed in the under sides of the projections 117-117a. The extension 115 and the slots 111 and 113 prevent the cover 105 from being blown oil? the arc chute by the pressure of the arc gases, and provide a fairly tight interlocking joint between the arc extinguisher and the casing.

Disposed adjacent the left-hand end of the arc extinguisher is an angular arc runner 121 of magnetic material such as sheet steel having an upper portion disposed between the upper portion of plug-in connectors 23 and the conducting member 22 on which the stationary contact 15 is supported. The lower portion of the arc runner 121 extends downwardly at an angle and terminates at a point adjacent the bight of the left are plate 95. The are runner 121 is held in place by the engagement of lugs 123 thereon with notches 125 in the side walls of the arc extinguisher housing. It will be noted that the lower end of the are runner 121 slightly overlaps and rests on the end of an upwardly extending portion 127 of the insulating bottom portion of the arc extinguisher housing. On low-current breakers the steel arc runner 121 may not be needed and the fibre extension 127 will then extend up under the conductor 22 and close the end of the arc chute in the same manner as the arc runner 121.

The are runner 121 of magnetic material performs several important functions. The magnetic material attracts the end of the are adjacent to the stationary contact 15 and moves it downwardly into the arc chute where the arc and its hot gases come in contact with the U- shaped plates 95. This cools and deionizes the arc and its gases. Without the runner, one end of the arc would remain on the stationary contact 15 and the plate 95 nearest to this contact would not be very effective. The are runner also cools the arc terminal as it travels across the surface of the runner and eliminates excess burning of the stationary contact.

The wide upper portion of the plug-in connector 23 is supported in recesses 129 (Fig. 1) and 129a (Fig. 3) respectively in the breaker housing 11 and in the cover 13. The plug-in connector 23 is formed to provide a pair of spaced, downwardly projecting blades 131 to permit engagement with a terminal or a bus bar connector (not shown).

A passage 133 for venting the hot gases is formed by the bottom wall 135 of the base section or housing 11 and the matching bottom wall 135a of the cover section 13, and by matching ribs 137 and 137a formed respectively on the base section 11 and the cover section 13 which ribs extend to the upperright hand corner of the U are extinguisher to form the stop 61. The matching ribs 137 and 137a conduct the arc gases under the thermalmagnetic trip device 21 and prevent the gases from coming in contact with the conducting parts thereof. It will be noted that the bottom portion of the cover 13 overlaps the bottom portion of the housing 11 as at 139 (Fig. 2) to form a tight seal for preventing leakage of the hot gases through the bottom wall of the breaker housing.

The are splitting plates 95 are slanted at an angle downwardly and away from the separating contacts, and the yoke portion of the right-hand arc plate 95 (Fig. l) is disposed adjacent the throat of the passage 133. The bottom corners of the arc plates 95 are notched to provide clear passages 141 (Figs. 2 and 4) for the hot gases along the bottom corners of the arc extinguisher housing to the passage 133 and out through the latter without obstruction.

It is to be noted that the vent passage 133 extends from the arc extinguisher 25 to the end of the breaker opposite the contacts and that the extinguishing plates 95 are slanted at an obtuse angle to the length of the passage 133 and toward the end of the breaker at which the passage vents the arc gases to atmosphere. The outer end 143 of the vent passage is slanted upwardly, being provided with a rib 145 having an inclined approach face to direct the gases above the metal mounting bracket 147 which may be at ground potential. This helps to avoid any possibility of flash-over from line to ground through the vent passage.

When the contacts separate, the are drawn therebetween moves down the arc runner 121 to the adjacent are splitter plate 95 and is then broken up between the arc plates and extinguished. The heat due to the arc causes an expansion of the air in the circuit breaker which blows the hot gases downward through the spacers between the plates 95, along the passages 141 and out through the passage 133. The legs of the U-shaped cover 195 or" the arc extinguisher extend inwardly (Fig. 2) far enough to cause a turbulence of the hot gases which might flow upwardly and substantially prevents the hot gases from moving out of the arc extinguisher housing into the space around the breaker operating mechanism. This action is aided by the fact that the plates 95 are slanted toward the vent passage 133 and are notched at the corners to provide the passages 141, thus making it easy for the gas pressure to be released without blowing up into the mechanism of the breaker. The cover plate 105 fits into the grooves 111 and 113 in the base and cover respectively, and acts as a barrier between the contact and terminal 23, which are at line potential, and the metal parts of the mechanism which are at the potential of the load terminal. There is then no direct path across the surfaces of the molded phenolic insulating material of the housing sections 11 and 13 between parts at opposite potentials.

With the construction described it has been made possible to eliminate the step of spraying the inside of the housing sections 11 and 13 adjacent the arc extinguisher with a coating of a composition to protect the molded material from being carbonized by are gases and providing a surface of low dielectric strength which could cause flash-over between the contact on the line terminal 23 and the mechanism parts at the potential of the load terminal 31. However, if increased dielectric strength is desired, the spraying may be used.

Having described the invention specifically in accordance with the statutes, it is to be understood that various changes and modifications can be made without departing from the spirit of the invention.

We claim as our invention:

1. A circuit interrupter including an enclosing casing of molded insulating material and separable contact means disposed adjacent one end wall of said casing for establishing an are, are extinguishing means for extinguishing the arc comprising a plurality of spaced slotted plates slanted away from said separable contact means, an insulating housing supporting said plates, a metallic arc runner disposed in said housing adjacent said contact means and terminating proximate to the adjacent one of said plates at one end of said housing for drawing the arc to said plates, and portions of said casing molded integral therewith forming a passageway extending from the other end of said are extinguisher housing to the end of said casing opposite said contact means for venting the gases of the arc.

2. A circuit interrupter including a casing of molded insulating material for enclosing said interrupter, contact means comprising stationary and movable contacts for drawing an arc, arc extinguishing means for extinguishing the arc comprising a plurality of spaced slotted plates, a U-shaped insulating housing for supporting and enclosing said plates, a terminal connector supported in said casing and having a conductor extending into one end of said are extinguisher housing for supporting said stationary contact, a projection on said casing adjacent said conductor, a cover on said are extinguisher housing having a portion extending under said projection into the space between said conductor and said projection, said cover having openings therein for receiving projections on said housing to hold said cover in place, a wall molded integral with said casing and terminating adjacent the other end of said arc extinguisher housing, said wall cooperating with other portions also molded integral with said casing to form a passageway extending from said are extinguisher for venting the gases of the are out of said casing at the end thereof opposite said contact means.

3. A circuit interrupter including a casing of molded insulating material for enclosing said interrupter, contact means comprising stationary and movable contacts for drawing an are, are extinguishing means for extinguishing the are comprising a plurality of spaced slotted plates, a U-shaped insulating housing for supporting and enclosing said plates, a terminal connector supported in said casing and having a conductor extending into one end of said are extinguisher housing for supporting said stationary contact, an arc runner supported on said housing and having one end disposed adjacent said conductor and the other end disposed proximate to the adjacent slotted plate of said are extinguisher, a projection on said casing adjacent said conductor, a cover on said arc extinguisher housing having a slot therein for receiving said movable contact and having a portion extending between said conductor and said projection, a wall molded integral with said casing and terminating adjacent the other end of said are extinguisher housing, said wall cooperating with other portions also molded integral with said casing to form a passageway extending from said are extinguisher for venting the gases of the are out of said casing at the end thereof opposite said contact means.

4. A circuit interrupter having an enclosing casing formed of two pieces of molded insulating material, stationary and movable contacts for establishing an are, an arc extinguisher structure for extinguishing the arc comprising a plurality of spaced slotted plates, a U-shaped insulating housing for supporting said plates, a terminal supported in said casing and having a conducting portion extending into one end of said are extinguisher for supporting said stationary contact within said housing, a cover of insulating material for said are extinguisher housing, each piece of said casing having a recess therein for receiving one of the opposite edges of said cover, means molded integral with said casing pieces forming a passageway extending to the opposite end of said casing from said terminal for venting the gases of the are, said passageway having an enlarged portion disposed adjacent the opposite end of said are extinguisher housing from said contacts and into which one end of the arc extinguisher extends.

5. A circuit interrupter including an open-sided casing of molded insulating material and a closure member also of molded insulating material mounted on the open side of said casing, stationary and movable contacts disposed adjacent one end wall of said casing for establishing an are, an arc extinguisher comprising a plurality of spaced slanted plates, an insulating housing for supporting said spaced plates, a terminal member of conducting material supported at one end of said casing and having a portion extending into one end of said are extinguisher housing for supporting said stationary contact, and said opensided casing and said closure member having portions molded integral therewith cooperating to form a passageway from the other end of said are extinguisher housing to the end of said casing opposite said terminal to vent the gases heated by the arc, and said slanted plates being slanted away from said contacts and toward said passageway.

6. A circuit interrupter including an open-sided casing of molded insulating material and a closure member also of insulating material mounted on the open side of said a casing, stationary and movable contacts for establishing an are, an arc extinguisher comprising a plurality of spaced plates, an insulating housing for supporting said spaced plates, a terminal member of conducting material supported at one end of said casing and having a portion extending into one end of said are extinguisher housing for supporting said stationary contact within said housing, said open-sided casing having portions molded integral therewith to form a passageway from the other end of said are extinguisher housing to the end of said casing opposite said terminal to vent the gases heated by the arc, and said spaced plates being slanted toward said passageway to direct the gases thereinto and out said end of the casing.

7. A circuit interrupter including an open-sided casing of molded insulating material and a closure member also of insulating material mounted on the open side of said casing, stationary and movable contacts for establishing an are, an arc extinguisher comprising a plurality of spaced parallel plates, an insulating housing for supporting said spaced plates, a terminal member of conducting material supported at one end of said casing and having a portion extending into one end of said are extinguisher housing for supporting said stationary contact, said open-sided casing having portions molded integral therewith to form a passageway from the other end of said are extinguisher housing to the end of said casing opposite said terminal to vent the gases heated by the arc, and said spaced plates being slanted toward said passageway and having spaces between the ends of the slotted plates and the insulating housing supporting them to provide a continuous passage from the spaces between the plates to said passageway to direct the gases thereinto and out said end of the casing.

8. A circuit interrupter including an open-sided casing of molded insulating material and a closure member also of molded insulating material mounted on the open side of said casing, stationary and movable contacts for establishing an are, an arc extinguisher comprising a plurality of spaced plates, an insulating housing for supporting said spaced plates, a terminal member of conducting material supported at one end of said casing and having a portion extending to one end of said are extinguisher housing for supporting said stationary contact within said housing, a metallic arc runner disposed in said are extinguisher housing adjacent said stationary contact and terminating proximate to the adjacent arc plate, and said open-sided casing and said closure member having portions molded integral therewith cooperating to form a passageway from the other end of said are extinguisher housing to the end of said casing opposite said terminal to vent the are gases, said portions of said casing and closure member cooperating with said arc extinguisher housing to hold said housing in place.

"9. A circuit interrupter including an open-sided casing of molded insulating material and a closure member also of molded insulating material mounted on the open side of said casing, stationary and movable contacts for establishing an are, an arc extinguisher comprising a plurality of spaced slotted plates of magnetic material, an insulating housing for supporting said spaced plates adjacent the path of opening movement of said movable contact, a terminal member of conducting material having a formed-over portion extending into an end of said are extinguisher housing for supporting said stationary contact, portions molded integral with said casing and said closure member forming an inwardly extending projection disposed adjacent the formed over portion of said terminal, a cover for said are extinguisher housing having a portion extending under said projection, portions molded integral with said open-sided casing and said closure member together forming a passageway extending from the other end of said are extinguisher housing to the end of said casing opposite said contacts for venting the gases of the arc, and said other end of said are extinguishing housing extending into the adjacent end of said passageway.

10. A circuit interrupter including an enclosing casing of molded insulating material, terminals at opposite ends of said casing, stationary and movable contact means disposed adjacent one end wall or" said casing for drawing an arc generally along the bottom of said casing, arc extinguishing means for extinguishing the are comprising a plurality of spaced slotted plates, an insulating housing supporting said plates, means for said casing defining a vent at the end of said casing opposite said stationary contact for venting the gases of the arc, and said spaced plates being slanted toward said vent to direct the gases thereinto and out said end of said casing.

11. A circuit interrupter including an enclosing casing of molded insulating material, terminals at opposite ends of said casing, stationary and movable contacts disposed adjacent one end wall of said casing for drawing an are generally along the bottom of said casing, an arc extinguisher comprising a plurality of spaced plates, an insulating housing for supporting said plates, means defining a vent passage at the end of said casing opposite said stationary contact, each of said spaced plates having notches at the corners thereof, said notches cooperating with said housing to form continuous passages extending along the bottom of said are extinguishing housing and into said vent passage leading to the end of said casing opposite said stationary contact, said spaced plates being slanted toward said vent passage to direct the gases thereinto and out said end of said casing.

12, A circuit interrupter having an enclosing casing formed of two parts of insulating material, terminals at opposite ends of said casing, stationary and movable contacts disposed adjacent one end Wall of said casing for drawing an are generally along the bottom of said casing, an arc extinguisher comprising a plurality of spaced slotted plates, an insulating housing for supporting said spaced plates, a cover for said housing, each of the two pieces of said casing receiving one of the opposite edges of said cover, means on said pieces of said casing forming a vent passage at the end of said casing opposite said stationary contact, said means on said pieces of said casing cooperating with said are extinguisher housing to hold it in place, and said spaced plates being slanted toward said vent passage to direct the gases thereinto and out of said end of said casing.

13. A circuit interrupter including an enclosing casing formed of two pieces of insulating material, terminals at opposite ends of said casing, stationary and movable contacts at one end of said casing for drawing an are generally along the bottom of said casing, an arc extinguisher comprising a plurality of spaced slotted plates, an insulating housing for supporting said plates, means defining a vent passage at the end of said casing opposite to said stationary contact, a cover for said are extinguisher housing, each of the two pieces of said casing receiving one of the opposite edges of said cover, each of said spaced plates having notches at the corners thereof cooperating with said housing to form continuous passages extending along the bottom of said casing and into said vent passage leading to the end of said casing opposite said stationary contact, and said spaced plates being slanted toward said vent passage to direct the arc gases thereinto and out said end of said casing.

References Cited in the file of this patent UNITED STATES PATENTS Von Hoorn Dec. 22, 1936 Graves, Jr June 3, 1941 Bingenheimer et a1 May 8, 1951 Thomas Feb. 3, 1953

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