US2303825A - Electric circuit breaker - Google Patents

Description

was, L 1942. H. E. cax

ELECTRIC CIRCUIT BREAKER Filed Aug. 7, 1942 I 2 Sheets-Sheet 1 IN SULATOR x HT 0 e W WM tEJo n 5t e t 3 m fim 9 Dec. 1, 1942. H, E. cox

ELECTRIC CIRCUIT BREAKER Filed Aug. '7, 1942 2 Sheets-Sheet 2 Inventor Harold E. Cox,

His Attornel Patented Dec. 1, 1942 ELECTRIC CIRCUIT BREAKER Harold E. Cox, London, England, assignor to GeneralElectric Company, a corporation 01' New York Application August 7, 1942, Serial No. 453,965 In Great Britain September 18, 1941 Claims. (Cl. 200-148) My invention relates to electric circuit breakers,'more particularly to those of the gas blast type and has for its principal object the provision of an improved and eflicient gas blast circuit breaker that is adapted to conserve the supply of arc extinguishing gas during a circuit breaker opening and reclosing cycle.

In a well known form of gas blast circuit breaker the separation of the contacts is controlled by the blast pressure that is also used for the arc extinguishing blast, The contacts are generally spring-biased toward closed circuit position so that when the blast pressure is removed the contacts reclose. This type of gas blast breaker is particularly adapted for automatic reclosing operations wherein it is desired to reclose the circuit and re-establish service immediately after the interruption of a fault are caused, for example, by lightning or other transient conditions.

It has also been proposed to interrupt large alternating current power arcs in two stages, by means of a gas blast, i. e., in the first stage the power current is interrupted by the main gas blast after a half cycle or so of arcing and in the second stage a resistance automatically is inserted in series in the circuit so that after interruption at a current zero, the current (assuming that the are re-ignites) is correspondingly reduced and a materially smaller gas blast is effective to extinguish the resistance current are. When a circuit breaker using this method is to be reclosed shortly after arc interruption, the supply of extinguishing gas used during the opening and reclosing cycle may be excessive even though the circuit is open for but a small interval of time.

In accordance with my invention the supply of interrupting gas is limited to the minimum practicable quantity by shutting off the main blast immediately after the interrupting operation and providing means operative when the main blast is discontinued for holding pressure on one part of the breaker so as to keep the breaker in open circuit position until actual reclosing is initiated. With this arrangement, the blast takes place only during the interrupting operation as contrasted with the entire period that the breaker is open.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

view, partly in section, of a modified form of my invention in the closed circuit position thereof.

Fig. 1 illustrates generally the plan view of an air blast circuit breaker of the load-break disconnecting switch type to which the present invention is particularly applicable. The circuit breaker comprises a pair of interrupting or are extinguishing units I and 2 that include relatively movable contact structure for controlling the circuit. The interrupting units I and 2 are mounted on supporting insulators 3 and 4, respectively, one of which is hollow and can be rotated about its vertical axis on a supporting base 5. As shown, the interrupting unit 2 is carried at the end of a tubular conducting switch arm 6 which is secured at its other end to the rotatable insulator 4. Accordingly, the relatively movable contact structures at I and 2 can be moved into and out of circuit controlling engagement with each other by rotation of the insulator support 4. The power line conductors diagrammatically indicated at I' and 2 are suitably connected to breaker terminals at the insulators 3 and 4.

The actuating means for rotating the insulator 4 may comprise any suitable arrangement, such as the gearing indicated at I and 8. When the circuit breaker is to be opened, the drive gear pinion 8 is rotated to cause counterclockwise rotation of the insulator gear 'I and the switch arm 6, thereby causing separation of the interrupting units I and 2. At the same time, an arc extinguishing gas under pressure such as air, is admitted to the units I and 2 from the gas supply lines 9 and I0, respectively. These supply lines are controlled by a three-way valve II hereinafter described for admitting the interrupting gas from a main supply source of pressure indicated at S. The supply line 9 leads directly to the interrupting unit I and the supply line I 0 communicates with-the interrupting unit 2 through the tubular switch arm 6 and the hollow insulator 4. As the arm forms between the separating contact structures, it is subjected in a manner hereinafter described to a blast of the interrupting gas and the circuit is thereby interrupted.

Further opening movement of the switch arm 8 serves to isolate the interrupting units in the open circuit position, When the breaker is to be closed. the switch arm 6 is rotated clockwise until the contact structures engage with each other. A gas blast circuit breaker of this general character is disclosed in Biermanns Patent No. 2,084,885, granted June 22, 1937, for Electric circuit breaker, and assigned to the same assignee as the present invention.

The interrupting units I and 2, referring now to Fig. 2, are provided with coacting tubular contacts I2 and I3 respectively and are substantially similar in construction and arrangement. Re-. ierring specifically to the interrupting unit I, the contact I2 and its control means, etc., are mounted within an insulating housing I 4 that is suitably mounted on the fixed insulator 3. The insulating housing may be of a suitable molded material of high mechanical and dielectric strength and has a switching and blast chamber I5 communicating with the exterior by way of a blast exhaust opening I6 through which the movable contact I2 also operates. The insulating housings of both contact structures are provided at the arcing ends with convex-shaped shields as indicated at I4. The operating means for the contact l2 comprises a piston II operable within a cylinder I8 also mounted at least in part at one end of the chamber I5. Th piston is spring biased at I9 so that the contact I2 is normally urged outwardly towards circuit making engagement with the unit 2. The cylinder is provided with an opening 20 for admitting gas under pressure to the piston and causing retraction of the contact against the bias of its closing spring. The tubular contact I2 is provided with an aperture I2 at a point within the cylinder I8 for admitting interrupting gas from the supply line 9 so that substantially simultaneously with the contact opening movement a blast of gas is directed out of the arcing end of the contact.

The interrupting unit 2 is sufficiently similar in structure so that the same reference numerals are used to indicate corresponding parts. An essential difference is that the tubular contact I3 is smaller in diameter, thereby providing for a gas blast of lower intensity, and its biasing spring is weaker than the spring of the contact I2. As in the case of the unit I, admission of gas under pressure to the cylinder I8 through the tubular switch arm 6 causes retraction of the contact I3 and a blast of gas from the open arcing end of the contact.

For the purpose of interrupting the are by the resistance method above referred to, an auxiliary electrode H is arranged in series with a suitable resistance 22 in shunt circuit across th interrupting unit I. In the specific arrangement shown, the auxiliary electrode is provided with a ball-like arcing tip 23 positioned in the path of the contacts I2 and I3 so that in the closed circuit position the contacts abut and are bridged by the conducting ball 23. The auxiliary electrode is normally spring-biased as at 24 toward the unit 2 so as to close in the manner of a ball valve the blast exhaust opening as illustrated. In the closed circuit position, the spring I9 02 the unit I is sufficiently strong not only to bias the ball portion 23 to its valve seating position against the spring pressure of the contact I3 but also to hold it in its seated position against normal blast pressure within the unit 2.

The operation of the circuit breaker is as follows: When the breaker, as shown in Fig. 2, is to be opened for interrupting a power circuit the valve II is operated by suitable control means (manual means 25 being illustrated in the present instance in the interest of simplicity) to admit pressure gas from the supply source to the pipes 9 and I0. This corresponds to position 0 of the valve. Reference is now made to Fig. 3 which shows the breaker during the arc extinguishing operation. The blast pressure in the interrupting units I and 2 has now retracted the contacts I2 and I3 so that the power are between the contacts is subjected to the individual gas blasts from the open ends of the contacts, and, when the contacts are fully retracted, through the exhaust blast exhaust openings I5. As previously described, the auxiliary electrode arcing portion 23 is interposed in the arc path and is blown by the blast from the unit 2 to the intermediate position shown. The main interrupting blast at the unit I serves to extinguish the power arc within a half cycle or so of arcing, thereby inserting the resistance 22 in the circuit. When and if the arc re-ignites on the next cycle, the reduced current are between the auxiliary electrode 2I and the contact I3 is easily extinguished in the next half cycle or so by the reduced blast from the unit 2.

Since the arc is now interrupted and the circuit cleared, there is no further necessity for the interrupting blast. Immediately following are interruption, the valve II is operated to the isolating or holding position indicated at I in Fig. 4. In this position, the valve shuts oil? the blast at unit I but maintains the blast pressure at the unit 2. Consequently, the contact I2 under bias of its stronger spring forces the electrode portion 23 to its plugging" position over the blast exhaust opening of the unit 2 thereby preventing further loss of the gas supply. The gas pressure within the unit 2 continues to hold contact I3 retracted so that breaker is held in its open circuit position without wastage of gas. When the breaker is to be reclosed the valve is operated to the initial closed circuit position indicated at C. The blast pressure now being completely removed, the contact springs return the contacts to closed circuit position in abutting relation with the auxiliary electrode.

In case the breaker is not to be reclosed at once, the unit 2 is rotated counterclockwise to a greater isolating distance from the unit I in the manner previously described. In this position the blast pressure is completely removed from both units.

In the modified form of my invention shown by Fig. 5, the auxiliary electrode shown at 28 is permanently mounted on and lmbedded in the unit 2 and is electrically connected to the resistance 22 in the manner above described. The electrode comprises an annular conducting disklike member having a central blast opening at 21 and is positioned for butt contact engagement with the contacts I2 and I3. Th blast opening 21 is in alignment with the tubular contacts in the manner illustrated. The operation is substantially the same as in the previous case since removal of the gas pressure at the unit I serves to cause plugging of the gas exhaust opening of the unit 2 by the contact I2. At the same time the gas pressure is held on the unit 2 to keep th breaker open until it is to be reclosed, thereby conserving the gas supply.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States:

1. An electric circuit breaker of the gas blast type comprising relatively movable contacts separable to form an interrupting arc gap, means for directing gas under pressure to said contacts for causing separation thereof and for interrupting arcing, means normally biasing said contacts toward closed circuit position, and means operable when the gas pressure at one of said contacts is removed after arc interruption for blocking gas flow and holding the gas pressure at another of said contacts thereby maintaining the breaker in open position after discontinuance of the interrupting blast.

2. An electric circuit breaker of the gas blast type comprising two arc extinguishing chambers, means for directing gas under pressure to said chambers for causing a gas blast at each chamber to interrupt arcing, and means operable in accordance with the shutting off of gas pressure at one of said chambers for blocking the flow of gas from the other of said chambers.

3. An electric circuit breaker of the gas blast type comprising two are extinguishing chambers, means for directing gas under pressure to each of said chambers for interrupting arcing by gas blast action, and means operable by and in accordance with the removal of gas pressure at one of said chambers for blocking the flow of gas from the other of said chambers while maintaining gas pressure in said other of said chambers.

4-. An electric circuit breaker of the gas blast type comprising two are extinguishing chambers, means for directing gas under pressure to each of said chambers for interrupting arcing by gas blast action, and means operable in response to shutting oil of gas at one of said. chambers for stopping the blast flow of gas from the other of said chambers, the last-named chamber being arranged to contain interrupting gas under pressure after stopping of said blast flow.

5. An electric circuit breaker of the gas blast type comprising two arc extinguishing chambers, relatively movable contacts separable to form interrupting gaps at said chambers, means for directing gas under pressure to said chambers for causing separation of said contacts and interrupting of arcing by gas blast action, and means operable in accordance with the shutting oil! of gas pressure at one of said chambers for permitting partial closing of said breaker and stopping the blast of gas from the other of said chambers, the last-named chamber thereby being under gas v pressure, one of said contacts being biased by said gas pressure to hold the breaker in open circuit position.

6. An electric circuit breaker of the gas blast type comprising two arc extinguishing chambers, contacts separable to form an arc gap in each of said chambers, means for directing gas under pressure to each of said chambers for separating said contacts and interrupting arcing, and means including one of said contacts operable in response to the shutting oil of gas pressure thereto and to one of said chambers for blocking the flow of gas from the other of said chambers and for holding another of said contacts under gas pressure to keep the circuit open.

7. An electric circuit breaker of the gas blast type comprising relatively movable contacts separable to form an interrupting arc gap, means for directing gas under pressure separately to said contacts for causing separation thereof and for interrupting arcing by gas blast action, means biasing said contacts toward closed circuit position, and means including one of said contacts operable when the gas pressure at said one of contacts is removed after arc interruption for blocking gas flow and holding the gas pressure at another of said contacts thereby maintaining the breaker in open circuit position after discontinuance of the interrupting blast.

8. An electric circuit breaker of the gas blast type comprising two movable contacts separable to form an interrupting arc gap, means for directing gas under pressure separately to said contacts for causing separation thereof and for interrupting arcing by two individual gas blasts, means biasing said contacts toward closed circuit position, and means including one of said contacts operable when the gas pressure at said one of said contacts is removed after arc interruption for blocking the blast flow and holding the gas pressure at the other of said contacts thereby holding said last-named contact in open circuit position after discontinuance of the interrupting blast and until said breaker is to be reclosed.

9. An electric circuit breaker of the gas blast including said auxiliary electrode operable when the gas pressure at one of said contacts is removed after arc interruption for blocking gas flow and holding the gas pressure at another of said contacts thereby maintaining the breaker in open position afterdiscontinuance of the interrupting blast.

10. An electric circuit breaker of the gas blast type comprising relatively movable contacts separable to form an interrupting arc gap, an auxiliary electrode positioned at an intermediate point in said gap for inserting a resistance in the circuit during the interrupting operation, means for directing gas under pressure to said contacts for causing separation thereof and for interrupting arcing by blast action along said arc gap, means biasing said contacts toward closed circuit position, and means including one of said contacts operable when the gas pressure at said one of said contacts is removed after arc interruption for engaging said auxiliary electrode and blocking gas flow and holding the gas pressure at another of said contacts thereby holding said last-named contact in open circuit position after discontinuance of the interrupting blast.

HAROLD E. COX.

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