US3489870A - Cascaded electric current interrupting device with ionized gas assisting in breakdown and eventual arc extinction - Google Patents

Description

Jan. 13, 1970 R. L. HURTLE 3,489,870

CASCADED ELECTRIC CURRENT INTERRUPTING DEVICE WITH IONIZED.

GAS ASSISTING IN BREAKDOWN AND EVENTUAL ARC EXTINCTION Filed Sept. 22, 1967 LOAD FMLZ WWM@@ A TT'ORA/E Y United States Patent O US. Cl. 200-444 11 Claims ABSTRACT OF THE DISCLOSURE A novel parallel assisted current interrupting device uses a plurality of arc dissipating devices each having arc chutes with diverging arc runners and arranged in a linear sequence generally in end-to-end relationship and connected in parallel with a circuit breaker which will generate an arc at the converged end of the first arc chute in the linear sequence. After the arc has travelled along the diverging arc runners of the arc chute, charged particles conducted from the diverged end of the arc chute t the converged end of the adjacent arc chute will reduce the breakdown potential in the adjacent device so that an arc will be drawn therein and current transferred thereto.

BACKGROUND OF THE INVENTION Various techniques for assisting current interruption have been proposed to extend the range and the capability of contact opening circuit breakers. Because of the limitations of circuit breaker construction, one technique employs parallel assisted circuit interruption wherein part or all of the interruption current is transferred from the primary circuit breaker to a parallel circuit which assists in the carrying of the current which is to be interrupted and within which final extinction of the current may take place. These devices have proven highly advantageous in operation but generally have been relatively complex in construction and relatively costly to manufacture.

In the copending application Ser. No. 768,963, Hurtle and Willard, filed Oct. 10, 1968, and assigned to the same assignee as the present invention, a highly desirable elec-. tric circuit breaker of novel construction and operation is disclosed which is capable of generating and maintaining an arc voltage during interruption which substantially exceeds the line voltage of the power system in which the circuit breaker is designed to be used. A parallel assisted current interruption apparatus utilizing such a circuit breaker is disclosed in the copending application of Hurtle, Ser. No. 542,806, filed May 15, 1966, now Patent No. 3,430,016, and assigned to the same assignee as the present invention. In this device, the high are voltage created in the circuit breaker is utilized to supply the triggering potential for a control breakdown gap device.

It will be appreciated that the device of the aforementioned Hurtle application affords many significant advantages in operation because of its very high performance characteristics. Nevertheless, such devices are limited in application because of the cost and relative complexity of the construction.

In the copending application of Henry G. Willard, filed concurrently herewith and entitled, Parallel Assisted Electric Current Interrupting Device, assigned to the same assignee as the present invention, there is disclosed and claimed a novel and effective arrangement wherein the charged particles produced by the arc are conducted between a plurality of arc chutes to form an arc sequentially therein. By this use of a plurality of arc chutes sequentially triggered by the charged particles, the arc may be accommodated until the current reaches the null point and is extinguished.

3,489,870 Patented Jan. 13, 1970 It is an object of the present invention to provide a novel parallel assisted circuit interrupting device utilizing a plurality of arc dissipation devices which may be readily and relatively economically manufactured.

Another object is to provide such a current interruption device which is of compact construction and adapted to design for a relatively wide range of current.

Still another object is to provide such a circuit interruption device having a minimum of moving parts and open; able without special environments or costly operating components and which is substantiailly free from any need for matching or adjusting components.

Other objects of the invention will in part be pointed out in the following detailed description and in part will become obvious from the following detailed description of specific embodiments of the invention, and the scope of the invention will be pointed out in the appended claims.

SUMMARY OF THE INVENTION It has now been found that the foregoing and related objects can be readily attained in a circuit interruption device having a plurality of arc dissipation devices arranged in sequence and each having an arc chute providing diverging arc runners for moving an are along a predetermined expanding path in an atmosphere of charged particles. The are chutes of the several arc dissipation devices are arranged linearly in generally end-to-end relationship and the several devices are electrically connected in parallel. An electric circuit breaker for connection in an electric circuit to be controlled by the circuit interruption device includes a pair of relatively movable contacts for generating an are at the converged end of the first arc dissipation device of the linear sequence to produce an atmosphere of charged particles therein. Gas conduit means extend between the diverged ends of the arc chutes of the arc dissipation devices and the converged ends of the arc chutes of the next adjacent arc dissipation devices in the linear sequence to conduct charged particles therebetween in sequence to form an are sequentially in the plurality of arc dissipation devices by reducing the breakdown potential in the succeeding arc dissipation device after the arc has travelled along the expanding path in the device adjacent thereto.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a semi-diagrammatic illustration of a current interrupting device incorporating the present invention; and

FIGURE 2 is a sectional view thereof generally along the line 22 of FIGURE 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detail to the attached drawing, the invention is shown as incorporated in an electric circuit current interrupting device in a circuit having a line terminal 10 and a load terminal 12. The lowermost rectangular area defined by the dotted lines generally indicated by the numeral 14 indicates a combined high are voltage gener ating circuit breaker and are dissipation device (hereinafter referred to as the main circuit breaker) which is electrically connected in parallel with second and third are dissipation devices outlined by the dotted lines and generally indicated by the numerals 16 and 18 respectively. The devices 14, 16 and 18 are disposed within a common housing of insulating material diagrammatically shown by the external dotted line surrounding the several devices.

The main circuit breaker 14 is described more fully in the aforementioned copending application Ser. No. 457,557, Hurtle and Willard, filed May 21, 1965, and assigned to the same assignee as the present invention so that it will be only briefly described herein. Generally, the main circuit breaker 14 includes a pair of spaced stationary contacts 20, 22 at the converging ends of diverging runners 24, 26 defining an arc chute. A generally wedge-shaped movable contact member 28 is carried at the end of a contact operating rod 29 and has contact faces which cooperate with the contacts 20, 22.

A generally cup-shaped insulating enclosure 30 surrounds the area about the movable contact member 28 and the contacts 20, 22 to form a pressure chamber 32 as will be more fully pointed out hereinafter. A first blowout coil 34 is connected between the stationary contact 20 and the line terminal 10, and a second blow-out coil 36 is connected between the stationary contact 22 and the load terminal 12 through the solenoid coil 38 which operates the contact operating rod 29. Special magnetic pole pieces (not shown) direct the flux generated by the coils 34, 36 to the arc area in a manner described hereinafter.

The current follows a path from the line terminal through the main circuit breaker 14 and blow-out coil 34 to the stationary contact 20. It then flows through the movable contact member 28 to the stationary contact 22, and thence through the blow-out coil 36 and solenoid coil 38 to the output terminal 12.

As will be appreciated, the stationary contacts 20, 22 with the arc runners 24, 26 and the blow-out coils 34, 36 are important components of an arc extinguishing device. In addition, a plurality of relatively closely spaced arc cooling plates or fins 40 are provided on the wall of the housing at the diverged end of the arc runners 24, 2 6 and disposed in a row extending transversely of the direction of arc movement.

The movable contact member 28 is normally retained in closed circuit position, i.e., with its contact faces in contact with the stationary contacts 20, 22 by suitable means (not shown) which may be manual and/or automatic. The movable contact member 28 is, however, movable from a closed to the open circuit position shown in FIGURE 1 by the action of the solenoid 38 upon the passage of a sufficiently high current therethrough, irrespective of the condition of such manual and/or automatic operating mechanism. The movable contact member 28 is shown in an extended or open position in FIGURE 1 for convenience.

The second and third are extinguishing devices 16, 18 are similar in construction to the arc extinguishing portion of the main circuit breaker 14. Both have diverging pairs of arc runners 42, 44 and 46, 48 respectively providing arc chutes, and blow-out coils 50, 52 and 54, 56 connected between the respective arc runners and the line and load terminals 10, 12 in parallel with the main circuit breaker 14. At the diverged ends of the are runners 42, 44 and 46, 48, the housing side walls are provided with a plurality of arc cooling plates or fins 58, 60 which extend in a row transversely of the direction of arc movement.

Extending between the outer ends of the outermost of the arc cooling plates 40 of the main circuit breaker 14 and the converged ends of the arc runners 42, 44 of the second arc dissipation device 16 is a gas conduit provided by a pair of converging wall members 62 of insulating material which will channel ionized particles and hot gases from the arc cooling plates 40 into the arc chute provided by the arc runners 42, 44. Similar converging wall members 64 provide a gas conduit between the ends of the arc cooling plates 58 of the arc dissipation device 16 and the converged end of the arc chute defined by the arc runners 46, 48 of the third are dissipation device 18.

At the outermost end of the third are dissipation device 18 and of the common housing is a muffle (not shown) of conventional construction through which the hot gases exit from the housing. The muflle is designed to limit the sound generated by the device and control the gas flow.

In the illustrated embodiment, connected in series with the blow-out coil 52 of the second arc dissipation device 16 is a high positive temperature coefficient resistor 66, and a similar resistor 68 is connected in series with the blow-out coil 56 of the third are dissipation device 18. Generally, such resistors are fabricated from a metal having a high positive temperature coefficient such as iron, tungsten and molybdenum and will increase in resistance from 10 to 20 times from the normal resistance within the temperature range of operation of the are dissipation device.

As the current flows through the resistor and through the arc dissipation device, the temperature rapidly increases with a great increase in the resistance of the resistor. With such resistors, the initial or cold value of the resistor may be relatively low so as to permit ready transfer of the arc to the arc chute from the preceding device. As the current begins to flow therethrough, the heating increases the resistance of the resistor and thus increases the voltage drop and reduces the current. The increased voltage drop facilitates transfer from the second arc extinguishing device to the third arc extinguishing device 18. As a consequence, the overall circuit transiently alters its power factor so as to bring the interrupted current flowing therethrough into phase with the supply voltage, and the current is driven to zero more nearly simultaneously with the supply voltage.

In addition, the resistor 66 in the second arc dissipation device 16 permits an increase in the resistance of the resistor 68 in the third are dissipation device 18 since it increases the voltage drop of the are before it is transferred therebetween. Exemplary of the resistors which may be employed are a resistor 66 having a cold resistance developing 500 volts and a hot resistance developing 5000 volts and a resistor 68 having developing 4000 volts when cold and 40,000 volts when hot.

In operation of the circuit interrupting devices of the present invention, the main circuit breaker will be in the closed position and connected in series with a suitable load (not shown) across a source of electrical power (not shown). All of the current flowing in the circuit will normally pass through the main circuit breaker 14. Upon the occurrence of a short circuit condition, the current in the circuit will increase extremely rapidly to a predetermined value which will actuate the solenoid 38 to move the movable contact member 28 in the opening direction (i.e., to the position shown in FIGURE 1).

As the movable contact member 28 moves towards the open circuit position, a pair of short arcs is drawn between the stationary contacts 20, 22 and the cooperating faces of the movable contact member 28, which are immediately forced together by their own magnetic fields combined with the action of the gas generated by the arc impinging upon the adjacent insulating material. The single are thus formed between the stationary contacts 20, 22 rapidly moves out along the diverging arc runners 24, 26 as the pressure in the chamber 32 increases due to the heating action on the gaseous atmosphere produced by the arc.

As the arc moves along the arc runners 20, 22 towards the diverged end thereof, a portion of the gaseous atmosphere containing charged particles flows through the conduit defined by the converging wall members 62 into the constricted chamber at the converged ends of the arc runners 42, 44 of the arc interrupting device 16 under the influence of the pressure in the arc chute of the main circuit breaker 14 so as to produce an atmosphere of charged particles Within the arc chute of the device 16. When sufficient charged particles have been transported into the chute defined by the runners 42, 44 so as to produce a breakdown potential therebetween, an arc will be drawn between the converged ends of the arc runners 42, 44 and current will flow through the arc dissipation device 16. Since the high voltage drop now existing between the arc runners 24, 26 of the main circuit breaker 12 is considerably in excess of that between the are runners 42, 44 at the point where the arc is initially drawn,

the simultaneous transfer of current to the are runners 42, 44 and continuing increase in resistance in the are between the arc runners 24, 26 will result in the extinguishing of the arc in the main circuit breaker 14.

It will be appreciated that the are between the arc runners 42, 44 will similarly tend to move outwardly and increase in length so that the voltage drop will increase, which effect is greatly accentuated by the resistor 66. As the arc moves outwardly along the arc runners 42, 44 in the second device 16, charged particles from it are conducted by the converging wall members 64 into the converged end of the arc runners 46, 48 of the third device 18. As the arc moves to the end of the arc runners 46, 48, such charged particles cause a sufiicient lowering of the breakdown potential in the third device 18 so as to cause the arc to be drawin therein. Again, the voltage drop will increase as the arc moves outwardly along the arc runners 46, 48, and the resistor 68 greatly magnifies this effect.

If the several elements have been properly dimensioned and the resistors properly selected, the short circuit current should be brought into place with the supply voltage and driven to zero concurrently with the supply voltage so that the arc is extinguished before it reaches the end of the arc runners 46, 48. Then, the hot gases are vented to the atmosphere through the mufile (not shown). The are cooling plates 40, 58 and 60 are conducting heat from the interior of the devices to the exterior walls of the housing to dissipate the heat generated by the arc.

It will be appreciated that some devices embodying the present invention may utilize four or more arc dissipation devices in series depending upon the current to be interrupted and the electrical characteristics of the several devices. Moreover, it is possible to utilize only two devices in the series.

Various configurations and constructions may be utilized for the arc dissipation devices so long as diverging arc runners provide an expanding arc chute and means to drive the are along the expanding path. In the preferred devices, to drive the arc outwardly along the diverging arc runners, a blow-out coil cooperates with each arc runner with one terminal electrically connected to its cooperating arc runner and its other terminal connected electrically to one of the contacts of the electric circuit breaker. In this manner, the plurality of arc dissipation devices are electrically connected in parallel with the circuit breaker through the blow-out coils.

Although the illustrated embodiment utilizes high temperature coefiicient resistors in series with the blow-out coils of the second and third arc dissipation devices, it is possible to omit such resistors albeit with less efiectiveness in developing maximum potential drop and optimizing power factor correction. Moreover, as previously indicated, such resistors so increase the potential drop that greatly increased resistance may be provided in the next device.

It will be appreciated that the stationary contacts of the main circuit breaker may be located adjacent the converged end of the arc runners of the first arc dissipation device instead of the preferred and illustrated arrangement wherein the pair of fixed contacts are actually supported on the converged end of the arc chute so that the arc will be drawn at the converged end of the chute itself. The gas conduit means between the several devices may assume a variety of forms but is most conveniently provided by simple walls on the housing which extend between the arc chutes. Although the several devices have been illustrated as disposed within a common housing, each may be individually encased with cooperating apertures in their housings to provide the gas conduit therebetween.

Thus, it can be seen that the circuit interrupting device of the present invention provides a novel means for effecting arc dissipation and may be readily and economically manufactured. The circuit interrupting device is of compact configuration and is adapted for utilization over a relatively wide range of current requirements and has a minimum of moving parts. Moreover, it is operable Without special environments and costly operating components and is also substantially free from any need for matching or adjusting components.

Accordingly, it is therefore intended by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

I claim:

1. A circuit interruption device comprising:

(a) a plurality of arc dissipation devices arranged in sequence and each having an arc chute providing diverging arc runners for moving an arc along a predetermined expanding path in an atmosphere of charged particles, the arc chutes of said plurality of arc dissipation devices being arranged linearly in generally end-to-end relationship and said devices being electrically connected in parallel;

(b) gas conduit means extending between the diverged ends of the arc chutes of said are dissipation devices and the converged ends of the arc chutes of the next adjacent arc dissipation devices for conducting charged particles therebetween in sequence to form an are sequentially in said plurality of arc dissipation devices by reducing the breakdown potential in the succeeding device after the arc has travelled along the expanding path in the device adjacent thereto; and

(c) an electric circuit breaker for connection in an electric circuit and including a pair of relatively movable contacts for generating an arc at the converged end of the linearly first of said plurality of arc dissipation devices and producing an atmosphere of charged particles therein.

2. The circuit interruption device in accordance with claim 1 wherein at least one of said arc dissipation devices includes a high positive temperature coefficient resistor which increases in resistance as the arc moves along the arc chute.

3. The circuit interruption device in accordance with claim 1 wherein said circuit breaker has at least one fixed contact at the converged end of said are chute of said first arc dissipation device and at least one contact movable with respect to said first contact to draw the arc therebetween which passes along the chute of said one device.

4. The circuit interruption device in accordance with claim 1 wherein said are chutes are enclosed within a common housing providing sidewalls extending therebetween and said sidewalls have a plurality of arc cooling fins adjacent the diverged ends of said chutes.

5. The circuit interruption device in accordance with claim 3 wherein said first contact is provided on the converged end of said are chute of said first arc dissipation device.

6. The circuit interruption device in accordance with claim 1 wherein said art interruption devices include a blowout coil cooperating with each arc runner, one blowout coil having one terminal electrically connected to its cooperating arc runner and its other terminal electrically connected to one of said relatively movable contacts of said electric circuit breaker, the other blowout coil having one terminal electrically connected to its cooperating arc runner and its other terminal electrically connected to the other of said relatively movable contacts of said circuit breaker, said plurality of arc dissipation devices being electrically connected in parallel with said circuit breaker through said blowout coils.

7. The circuit interruption device in accordance with claim 1 wherein said gas conduit means comprises insulating wall portions converging from the diverged end of one arc chute to the converged end of the adjacent arc chute.

8. A circuit interruption device comprising:

(a) a housing of insulating material;

(b) a plurality of arc dissipation devices arranged in sequence within said housing for moving an arc along a predetermined expanding path in an atmosphere of charged particles, said plurality of arc dissipation devices being electrically connected in parallel and each including an arc chute with a pair of diverging arc runners and are cooling fins on the sidewalls of said housing adjacent the diverged ends of said are runners, said are chutes being arranged linearly in generally end-to-end relationship;

(c) an electric circuit breaker for connection in an electric circuit including at least one first contact at the converged end of the arc chute of the linearly first of said are dissipation devices and at least one contact movable with respect to said first contact to draw an arc therebetween and produce an atmosphere of charged particles therein whereby the are thus drawn passes outwardly along the diverging arc runners of said first arc dissipation device; and

(d) converging gas conduits communicating between the diverged end of the arc chutes of said disipation device and the converged ends of the arc chutes of the next adjacent arc dissipation device in the linear sequence for conducting charged particles therebetween in sequence to form the arc sequentially in said plurality of arc dissipation devices by reducing the breakdown potential in the succeeding device after the arc has travelled along the expanding path in the device adjacent thereto, said are chutes being dimensioned so that an arc will be drawn in the arc chute of the succeeding device after the arc has travelled along substantially the full length of the diverging arc runners of the device adjacent thereto and the current is rapidly transferred to the succeeding arc dissipation device.

9. The circuit interruption device in accordance with claim 8 wherein said are interruption devices include a blowout coil cooperating with each arc runner, one blowout coil having one terminal electrically connected to its cooperating arc runner and its other terminal electrically connected to one of said relatively movable contacts of said electric circuit breaker, the other blowout coil having one terminal electrically connected to its cooperating arc runner and its other terminal electrically connected to the other of said relatively movable contacts of said circuit breaker, said plurality of arc dissipation devices being electrically connected in parallel with said circuit breaker through said blowout coils.

10. The circuit interruption device in accordance with claim 8 wherein said converging gas conduits are provided by insulating walls on the sidewalls of said housing extending from adjacent the ends of said are cooling fins to conduct the gas therefrom.

11. The circuit interruption device in accordance with claim 8 wherein at least one of said are dissipation devices includes a high positive temperature coefiicient resistor which increases in resistance as the arc moves along the arc chute.

References Cited UNITED STATES PATENTS 1,819,207 8/1931 Slepian 200-144 2,508,954 5/1950 Latour et a1 313-306 X 2,900,566 8/1959 Fischer 315-36 3,093,766 6/1963 Cobine 313-306 X 1,796,160 3/ 1931 Paul 200-147 3,448,231 6/1969 Heft 200-144 FOREIGN PATENTS 25,287 12/1905 Great Britain. 1,160,922 l/ 1964 Germany. 199,715 12/1965 Sweden.

ROBERT S. MACON, Primary Examiner R. A. VANDERHYE, Assistant Examiner US. Cl. X.R.

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