US2645694A - Cross blast circuit breaker with arcing contacts controlling orifice of arcing chamber - Google Patents

Description

y 14, 1953 c. D. AINSWORTH 2,645,694

CROSS BLAST CIRCUIT BREAKER WITH ARCING CONTACTS CONTROLLING ORIFICE OF ARCING CHAMBER Filed Feb. 15, 1949 Patented July 14, 1953' CROSS BLAST CIRCUIT BREAKER ITH ARCING CONTACTS CONTROLLING ORIFICEV or ARCING CHAMBER Chester D. Ainsworth, Wollaston, Mass, assignor to Allis-Chalmers Manufacturing Company,

Milwaukee, Wis., a corporation .of Delaware Application February 15, 1949, Serial No. 76,468

1 This invention relates to switching devices such as electric circuit breakers of the fluid blast type and more particularly to means for improving the interrupting capacity thereof. I V

In the operation of circuit breakers of the fluid blast type, the current interruption takes place under the most advantageous conditions when thearcing contacts are rapidly separated to permit the flow'therebetween of a blast of fluid of maximum velocity obtainable from the available source. In orderto be sure that restriking of the arc does not occur, isolating or disconnect contacts are frequently provided in addition to the arcing contacts and are opened after the arc has been extinguished butwhile the fluid blast is still being maintained. I

Heretofore, axialt'ype air blast circuit breaks ers employing a nozzle type fixed contact having an annular or circular contact surface and a cooperating movable plug contact have been used. At the time of separationof this type of contact, a small annular or circular gap is formed therebetween and the are formed upon separation thereof, during its state of inception,

extends transversely across the gap. Theblast this is conducive to low interrupting efficiency of the axial air blast circuit breaker using 00- operating nozzle and plug type arcing contacts. The above described limitations of the axial type circuit breaker employing cooperating nozzle and plug'type arcing contacts led to the development of axial type circuit breakers having diflierent types of arcing contact arrangements. One of the contact arrangements developed for interruption of high currents comprised an insulating gas blast nozzle and a pair of butt contacts arranged therein and separable in a direction longitudinally thereof. This type of arrangement proved to be capable of interrupting currents of higher magnitude than was possible with arrangements having nozzle and plug contacts, yet it had a definite drawback consisting in the fact that the upstream contact was an impediment limiting the effectiveness of'the air blast along the zone of the common geometrical axis of both contacts.

'5 Claims. (Cl. 200-448) 2 It is'therefore" one object of the present invention to provide a new and improved circuit breaker of the fluid blast type in which substantially all of the fluid passing through the circuit breaker over the engageable surfaces of its contacts flows in substantially a single direction transversely of the direction of separation of the arcing contacts.

A further object of the present invention is to provide a new and improved circuit breaker of the fluid blast type in which substantially all of the fluid blast is utilized in extinguishing the are formed upon separation'of arcing contacts embodied therein.

A still further object of the present invention is to provide a'new and improved circuit breaker of the fluid blast type in which the fluid blast is controlled and directed by the arcing contact structure. 7

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawings in which:

Fig. l is a diagrammatic view. partly in elevation of a circuit breaker embodying the present invention;

Fig. 2 is an enlarged view of an axial cross section through the interrupting head of the circuit breaker illustrated in Fig. 1; and

ment thereof a reservoir 2 constituting a source of supply fluid under pressure, which will be assumed herein to be compressed air, supplied from a suitable compressor (not shown). Al-

though in gener'al, circuit breakers of the type herein considered are provided with a plurality of similar switch elements or pole units to be inserted in the several conductors of a polyphase electric circuit, only one such pole unit is shown in Fig. 1 and the circuit breaker will be described in detail as if it were of the single pole typ The circuit breaker, for example, may comprise a fixed arcing contact 3 and a cooperating movable arcing contact 4 having mutually engageable surfaces connected in series with a I disconnecting switch comprising a fixed disconnect contact 5 and a cooperating movable disconnect contact 6 in an electric circuit through stud terminals 1 and 8. The arcing contacts 3 and 4 are housed in a tubular arcing chamber 9 having a metallic sleeve shaped wall axially aligned with and supporting an insulating sleeve II and an insulating sleeve 12. The metallic sleeve IU of chamber 9 constitutes a conductive connection between the fixed arcing contact 3 and an extension of terminal 8. Sleeve H constitutes a discharge passage wherein the are drawn between contacts 3 and 4 is forced by a gas blast.

Sleeve l 0, as more clearly illustrated in Fig. 2, is provided with an inwardly extendin bracket [3 upon which is arranged a contact constituting the fixed arcing contact 3 of the circuit breaker. Contact 3 forms an arc runner for directing the arc or are terminal downstream of the zone of arc initiation and into the discharge passage H. The cooperating movable arcing contact 4 is actuated by a piston 16 arranged for reciprocatory movement within a cylinder [4 which is axially aligned within insulating sleeve portion l2 and forms the cylinder for a fluid motor [1. Insulating sleeve I2 is partially closed at the upper end thereof by a diaphragm or perforated transversal partition I8 provided with apertures l9 and 20 for regulating the admission of air from metallic sleeve I0. Piston I6 is thus rendered operable by means of fluid under pressure introduced within sleeve H] for separating arcing contacts 3 and 4.

The movable arcing contact 4 is urged into engagement with the fixed arcing contact 3 by resilient means such as a spring 2| acting between a shoulder 22 mounted on a piston rod 23 and partition I 8.

The movable disconnect contact 6 may be pivotally mounted on a bracket 24 which is secured to an extension of terminal '1. One end of an insulating connecting rod 25 may be connected to movable disconnect contact 6 at a point 26 intermediate the ends thereof, and the other end A of rod 25 may be connected to an arm 21 of a bell crank 28. A second arm 3| of bell crank 28 may be connected to a piston rod 32 of a fluid motor 33. The rod 32 protrudes through and beyond the end of a cylinder 34 of motor 33.

Motor 33 actuates the bell crank 28 which, in turn, actuates the connecting rod 25. A predetermined movement of connecting rod 25 actuates the movable disconnect contact and moves it to its open and closed positions. A pair of regulating valves or needle valves 35 and 36 may be utilized for regulating the supply of fluid from reservoir 2 to motor 33.

A mechanical interlocking device for precluding improper sequence of operation of the disconnect corrtacts 5 and 6 with reference to the arcing contacts 3 and 4 is provided for proper circuit breaker operation. The mechanical interlocking device comprises a bent lever 31 which is pivotally mounted on a bracket 38 and arranged to lie within the path of relative movement of the arcing contacts, which, in the embodiment shown, is the path of movement of contact 4 or of the piston [6 which is actuated with contact 4. Lever 31 also lies in the path of relative movement of the disconnect contacts which, in the embodiment shown, is the path of movement of contact 6, for preventing separation of the disconnect contacts 5 and 6 prior to the opening of arcing contacts 3 and 4. A biasing means, such as a spring 39, pivots the lever 31 into the path of movement of the movable disconnect contact 6 and prevents separation thereof from the stationary or fixed disconnect contact 5 in case of maladjustment 0f the means which control the sequence of the fluid motor for operating arcing contact 3.

The compressed air for operating the circuit breaker control system and the arcing contacts is derived from the reservoir 2. The air under pressure in reservoir 2 also produces the are extinguishing blast across the gap formed between the pair of cooperating arcing contacts 3 and 4 upon separation thereof. The arc extinguishing blast from reservoir 2 to the arcing contacts 3 and 4 is controlled by a blast valve 40 which provides a connection between the reservoir 2 and a conduit 4| which is connected to the metallic sleeve portion In of chamber 9.

In accordance with the present invention arcing contacts 3 and 4 may be arranged to engage within a nozzle 42 which is preferably made of refractory insulating material and is arranged at the entrance of the passage formed by chamber 9. Nozzle 42 establishes a zone of high velocity for the blast of fluid under pressure supplied to chamber 9 from reservoir 2 through conduit 41. In order to utilize substantially all of the arc extinguishing blast of fluid under pressure a means, such as guiding surface 43 of nozzle 42 is provided for biasing the are formed upon initial separation of the arcing contacts 3 and 4 in a direction transverse to the direction of separation of the arcing contacts. Guiding means 43 provide a substantially rectilinear path through a gap formed upon separation of the arcing contacts 3 and 4 for the blast of gas under pressure.

The guiding means 43 which is arranged to provide a sinuous, tortuous or zigzag path comprises a first concave portion 44 extending from the upstream end of nozzle 42 to the area where the gap is formed upon separation of the arcing contacts 3 and 4, a portion 45 extending substantially parallel to the gap, a second concave portion 44a extending from the gap to the downstream end of nozzle 42. The portion 45 extending generally parallel to the gap i substantially perpendicular to a longitudinal axis 60 of the gap and arcing contacts 3 and 4. Thus, the guiding means are so arranged that the blast of gas sweeps in a single direction substantially the total contact engaging surface areas.

Arcing chamber 9 and particularly guiding means 43 incorporates the features of a cross blast circuit breaker into a conventional axial blast circuit breaker structure, thereby combining desirable features of both types of breakers into a single breaker structure. By axially aligning sleeve I2, which contains the actuating means for arcing contacts 3 and 4 and sleeve l0 and H a reduction of the overall dimension of the cross blast circuit breaker is obtained.

Fig. 3 illustrates more clearly the positioning of the portions 44, 45, and 44a which combine to form the guiding means 43 of nozzle 42.

The movable arcing contact 4 is so arranged as to control the amount of gas under pressure passing through nozzle 42 prior to as Well as during the time of contact separation. Movable contact 4, when in the closed position thereof, completely obstructs the orifice formed by the guiding means 43 of nozzle 42. In the open position thereof, movable contact 4 directs substantially all of the fluid passing through the orifice over the engageable surfaces of the arcing contacts 3 and 4. Sleeve ll may contain an auxiliary arcing or probe electrode 41 which is usually affixed thereto. The auxiliary arcing electrode 41 may be connected with the stationary arcing con- .tact' through a current limiting resistor 48 by 'means of a conductor 49.

tively, control the actuating means for the circuit breaker. Both control valves 55 and 56 are connected to reservoir 2 by a common conduit 5?.

A slide or piston type interlocking valve 58 is provided and arranged in a conduit 59, 39 for connecting the closing valve 56 and the fluid operated motor 33. This type of valve is more fully described and claimed in a copending application Serial No. 71,506 of John F. Chipman, filed January 18, 1949, now Patent No. 2,533,559 issued December 12, 1950.

The circuit breaker illustrated in Fig. 1 of the drawings is shown with the disconnect contacts in the open position and the pneumatic control system in the corresponding position. A closing operation is initiated by energization of the closing solenoid valve 56, thereby causing air under pressure from reservoir 2 to pass through conduit 51, valve 56, conduit 59, valve 58, conduit 59 to fluid motor 33., Operation of solenoid valve 56 results in a piston (not shown) of motor 33 moving from right to left to actuate rod 32, bell crank 28, and connecting rod 25, thus closing the disconnect contacts 5 and 6. The movement of the piston of fluid motor 33 from right to left rotates link 53 clockwise, and this results in an upward movement of connecting rod 52, which in turn rotates link 54 in a clockwise direction. The clockwise rotation of link 55 actuates slide valve 53 in an upward direction, thus opening a port from trip valve 55 to blast valve 40.

When the solenoid trip valve 35 is energized, compressed air flows from reservoir 2, through conduit 51, trip valve 55, and a conduit 68, through slide valve 50 and into blast valve 40. This initiates the operation of blast valve 40. Upon being opened, blast valve it permits a blast of air under pressure to flow through conduit il, an inlet port 69 of sleeve Hi, and into chamber 9. Air under pressure in chamber 9 actuates piston I6 and piston 16 opens the arcing contacts 3 and 4. Upon the separation of arcing contacts 3 and 4 a blast is provided which sweeps the arcing contacts 3 and i and their engaging surfaces. While the lines of flow of the air blast follow a complicated pattern'which varies during the interrupting process, in effect the blast is directed in substantially a single direction transverse to the movement of the movable arcing contact 4 and extinguishes the arc occurring upon separation of arcing contacts 3 and 4. The transverse air blast may be perpendicular with respect to the direction of movement of contact 4 or may be oblique withv respect thereto.

The path of the current flowing through arcing contacts 3 and 4 bends sharply near the contact engaging surfaces thereof, thus, forming a loopshaped current path which produces a magnetic means for aiding in biasing the are formed upon initial separation of the arcing contacts into chamber 9 downstream of the orifice formed by the guiding means 43 of nozzle 82.

Upon a predetermined travel of rod 23 which is actuated by piston IS, a portion thereof abuts against lever 31. The movement of lever 3'! moves one arm thereof out of the path of movement of the movable disconnect contact 3.

Upon the flow of the air blast through conduit 4|, air under pressure therefrom is transmitted through a conduit 10 connected thereto and to the left hand side of motor 33. This pressure impulse moves the piston of motor 33 from left to right, thus resulting in the separation of the disconnect contacts 5 and 6. If thedesired predetermined sequence of the actuating means for operation of the arcing contacts 3 and 4 and the disconnect contacts 5 and 6 does not occur, the lever 37 will prevent disconnect contacts 5 and 6 from separating. However, upon the proper sequence of operation lever 3! will be moved out of the path of movement of disconnect contacts Sand 6 without physical contact therewith before fluid motor 33 actuates disconnect contacts 5 andB.

Upon the flow of an air blast through conduit 4|, air under pressure therefrom is transmitted through a conduit H to valve 58. This pressure impulse closes valve 58 and precludes the possibility of air under pressure being supplied to motor 33 through conduit 59, which might result in improper closing of the disconnect contacts 5 and 6.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the inventionor from the scope of the appended claims. F

It is claimed and desired to secure by Letters Patent:

1. In an electric switching device the combination of an arcing chamber having an orifice, a discharge passage for said chamber, a source of fluid under pressure connected to said chamber to: cause a blast of fluid to pass through said orifice and said passage, a pair of cooperating arcing contacts arranged within said chamber to initiate an arc and comprising a fixed contact and a movable contact having mutually engageable surfaces, said movable contact arranged when in the closed position thereof to completely obstruct said orifice and in the open position thereof to direct substantially all of said fluid passing through said orifice over the said engageable surfaces of said contacts in substantially a single direction transverse to the direction of movement of said movable contact, said fixed contact forming an arc runner for directing the arc downstream from said orifice, an auxiliary contact arranged within said passage, and a resistor arranged outside of said chamber and connecting said auxiliary contact with one of said arcing contacts.

2. In an electric switching device the combination of an arcing chamber having an orifice, a

discharge passage for said chamber, a source of fluid under pressure connected to said chamber to cause a blast of fluid to pass through said orifice and said passage, a pair of abutting arcing contacts arranged within said chamber for initiating an arc and comprising a fixed contact, the contact engageable surface of which forms a part of the surface surrounding said orifice, an arc runner forming a part of said fixed contact for directing one terminal of the arc from said chamber to said passage, and a movable contact arranged when in the closed position thereof to completely obstruct said orifice and in the open position thereof to direct substantially all of said fluid passing through said orifice over the engageable surfaces of said contacts in a single direction transverse to the direction of movement of said movable contact, an auxiliary contact arranged Within said passage, and a resistor arranged outside of said chamber and connecting said auxiliary contact with one of said arcing contacts.

3. In an electric switching device the combination of an arcing chamber, a pair of separable abutting arcing contacts arranged within said chamber for initiating an arc, means for separating said arcing contacts to provide a gap therebetween, means connected to said chamber for producing an arc extinguishing blast of fluid under pressure across said gap, guiding means within said chamber and surrounding said contacts and said gap for defining a nozzle to direct substantially all said fluid passing through said gap over the engageable surfaces of said contacts in a single direction substantially perpendicular to the direction of movement of one of said contacts, said contacts when in the closed position thereof completely obstructing said nozzle, said nozzle comprising a first portion extending from the upstream end of said guiding means to said gap, a second portion extending through said gap substantially perpendicularly to the longi tudinal axis of said gap, and a third portion extending from said gap to the downstream end of said guiding means, said first portion defining a concave surface and said third portion defining a concave surface, an arc runner forming a part of one of said arcing contacts for providing a path for movement of one terminal of said are downstream of said nozzle, and means for providing a loop shaped path for the arc current including the said engageable surfaces of said contacts for magnetically biasing the are formed upon initial separation of said contacts from the gap formed between said contacts into said nozzle.

4. In an electric switching device the combination comprising a cylinder forming an arcing chamber, a pair of cooperating arcing contacts arranged within one end of said cylinder along the longitudinal axis thereof to initiate an arc and guishing blast of fluid to flow in substantially the opposite directions adjacent the arc, guiding means within said chamber and surrounding said contacts to direct substantially all of said arc extinguishing blast of fluid over the engageable surfaces of said contacts in a single direction substantially perpendicular to the direction of movement of said movable contact, said fixed contact providing an arc runner for directing one terminal of said are downstream of said guiding means, an auxiliary contact arranged within said chamber substantially along the longitudinal axis thereof downstream of said arcing contacts, and a resistor arranged outside of said chamber and connecting said auxiliary contact with one of said arcing contacts.

5. In an electric switching device the combination comprising an arcing chamber having an oriflce, a pair of cooperating arcing contacts arranged within one end of said chamber to initiate an arc and comprising a fixed contact and a movable contact having mutually engageable surfaces, said contacts when in the closed position thereof substantially completely obstructing said orifice, a fluid motor of the reciprocatory type arranged within another end of said chamber for actuating said movable contact, means comprising a single source of fluid under pressure connected to said chamber between said ends thereof for causing a first blast of fluid to flow in one direction for actuating said motor and for causing a second arc extinguishing blast of fluid to flow in an opposite direction adjacent said arc, said contact arrangement delaying said second blast until said contacts are opened by said motor in response to said first blast whereby the fluid supplied from said source to said chamber is initially trapped in said chamber to cause said motor to rapidly open said contacts, and guiding means within said chamber and surrounding said contacts and said orifice to direct substantially all of said arc extinguishing blast of fluid passing through said orifice over the engageable surfaces of said contacts in a single direction substantially perpendicular to the direction of movement of said movable contacts.

CHESTER D. AINSWORTH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,049,328 Skeats July 28, 1936 2,049,996 Clerc Aug. 4, 1936' 2,392,647 Cox Jan. 8, 1946 2,451,669 Eichenberger Oct. 19, 1948 FOREIGN PATENTS Number Country Date 85,565 Sweden Feb. 18, 1936

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