US3489871A - Electric current interrupting device with ionized gas assisting in breakdown and eventual arc extinction - Google Patents

Description

Jan. 13, 1970 H. G. WILLARD 39 3 ELECTRIC CURRENT INTERRUPTING DEVICE WITH IONIZED GAS ASSISTING IN BREAKDOWN AND EVENTUAL ARC EXTINCTION Filed Sept. 22, 1967 nv vav me Mew/er 6T M11420 United States Patent US. Cl. 200144 Claims ABSTRACT OF THE DISCLOSURE An electric circuit interrupter including a pair of spaced stationary contacts and a bridging contact member, together with a pair of elongated outwardly diverging arc runners and a pipe or conduit extending from the area adjacent the stationary contacts to the area adjacent a second pair of elongated outwardly diverging arc runners isolated by an insulating partition from the first arc runners, whereby ionized gases from between the stationary contacts are conducted to the space between the second arc runners to cause electrical breakdown between the second arc runners a short time after an arc has been drawn between the first arc runners, to thereby by-pass current around the first arc runners and assist in the current interruption.

The present invention relates to electric current interrupting devices, and more particularly, to a device of the type in which interruption of electric current in a loadcarrying circuit is achieved in a combination comprising a main circuit path and at least one parallel circuit path which assists in the interruption of current. For convenience, this technique of circuit interruption is referred to as parallel assisted current interruption.

In 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 effective electric 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 is achieved. A parallel assisted current interruption apparatus utilizing such a circuit breaker is disclosed in the co-pending application of Hurtle, Ser. No. 542,806, filed May 15, 1966, now Patent Number 3,430,- 016 and assigned to the same assignee as the present invention. In the latter device, the high arc voltage created in the primary circuit breaker is utilized to supply the triggering potential for a controlled breakdown gap device in the parallel or assisting circuit. The device of the Hurtle application affords many significant advantages in operation because of its high capacity performance characteristics. Nevertheless, the device is limited in application because of the necessity for and cost of the triggerable controlled breakdown gap device.

It is an object of the present invention to provide a parallel assisted circuit interrupting device which may be readily and relatively economically manufactured.

Another object is to provide such a current interruption device which is of compact configuration and adapted for use with a relatively wide range of currents.

Still another object is to provide such a circuit interruption device having a minimum of moving parts and operable without special environments or costly operating components and which is substantially 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.

It has 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 parallel and each having means for moving an are along a predetermined expanding path. The device includes a pair of relatively movable contacts associated with a selected one of such arc dissipation devices for generating an arc therein. Conduit means is provided communicating between the first arc dissipation device and the parallel connected arc dissipation device to conduct charged particles from the first to the second arc dissipation device to form an arc therein by reducing the breakdown potential therein, whereupon the current is transferred from the first dissipation device to the second, but at a reduced level, in a manner to be described, where it is finally extinguished.

The arc dissipation devices in a preferred form include an arc chute with diverging arc runners with walls extending therebetween having a plurality of arc cooling fins thereon. To drive the arc outwardly along the diverging runners, a pair of blowout coils is provided for each arc chute.

In many applications, only two such are dissipation devices may be required. However, in some instances, depending upon the current being interrupted and the dimensioning and electrical characteristics of the arc dissipation devices, it will be desirable to include three or more such arc dissipation devices connected in parallel, which will function similarly by transferring the arc successively to the several devices.

The invention will be more fully understood from the following detailed description, and its scope will be pointed out in the appended claims.

In the drawings,

FIGURE 1 is a semi-diagrammatic illustration of a circuit interrupting device incorporating the present invention;

FIGURE 2 is a semi-diagrammatic illustration in exploded form of a pair of arc chutes interconnected by a gas conduit for use in the circuit interrupting device of the present invention, and

FIGURE 3 is a semi-diagrammatic side elevational view of the circuit interrupting device of FIGURE 1.

Referring now in detail to FIGURE 1, the invention is shown as incorporated in an electric circuit current interrupting device having a line terminal 10 and a load terminal 11. The numeral 12 generally indicates a high are voltage generating circuit breaker, hereinafter referred to as the main circuit breaker, which is connected electrically in parallel with a second arc dissipation device generally indicated by the numeral 14 by connection at points 15 and 16, respectively.

The main circuit breaker 12 is described more fully in the aforementioned co-pending application Ser. No. 457,557, Hurtle and Willard, filed May 21, 1965, and assigned to the same assignee of the present invention so that it will be only briefly described herein.

The main circuit breaker 12 includes an insulating casing or support 17 (see FIG. 3) having a pair of spaced stationary contact assemblies 18, 19, mounted thereon (see FIG. 1) by suitable means, not shown. The contact assemblies 18, 19 include contacts 20, 21, respectively, whichare supported at the ends of the arc runners 22, 23, respectively, which diverge outwardly in a direction away from the contacts 20, 21. A generally wedge-shaped movable contact member 24 is carried at the end of a contact operating rod 25 and has contact faces 26, 27 which cooperate with the contacts 20, 21.

A generally-cup-shaped insulating enclosure 28 surrounds the area about the movable contact member 24 and contact faces 20, 21 to form a pressure chamber 29, as will be pointed out more in detail hereinafter. A first arc blowout coil 30 is connected between the stationary contact assembly 18 and the connection point 15 leading to the line terminal 10. A second blowout coil 31 is connected between the stationary contact assembly 19 and a solenoid coil 32, which in turn, is connected to the connection point 16 leading to the load terminal 11. Magnetic pole pieces, not shown, may be utilized to direct the flux generated by the coils 30, 31 to the arc area in a manner described hereinafter. The solenoid 32 includes a movable plunger portion 33 connected to the contact operating rod 25.

The current follows a path through the circuit breaker 12 whereby it flows from the terminal through to connection point and blowout coil to the stationary contact assembly 18 and its contact face 20. It then flows from the contact face 26 through the movable contact 24 and contact face 27 to the contact face 21 of the stationary contact assembly 19. From here, it flows to the blowout coil 31 and thence through the solenoid 32 to the connection point 16 and output terminal 11.

A plurality of relatively closely spaced arc cooling plates 35 is also provided on the wall 46 and disposed in a row extending transversely to the direction of arc movement, the end plates 35a, 351) being slightly longer than the other plates.

The movable contact member 24 is normally retained in closed circuit position, i.e., with the faces 26 and 27 in contact with the faces 20 and 21, respectively, by suitable means, not shown, which may be manual and/or automatic. In the illustrated embodiment, the movable contact 24 is movable from a closed to the open circuit position shown in FIGURE 1 by the action of the solenoid 32 upon the passage of a sufliciently high current therethrough. The movable contact member 24 is shown in an extended or open position in FIGURE 1 for convenience.

The arc extinguishing device 14 is generally similar in construction to the arc extinguishing portion of the main circuit breaker 12 and includes an arc chute generally designated by the numeral 37 providing an enclosed portion 38 at its lower end forming a pressure chamber 39. Extending from the pressure chamber 39 are are runners 40, 41 which diverge outwardly therefrom. A plurality of arc cooling fins 42 with longer end plates 42a, 42b are provided adjacent the outer ends of arc runners 40, 41 comparable to plates 35 are provided, disposed in a row extending transversely to the direction of arc movement.

A blowout coil 43 has one terminal connected to the arc runner and its other terminal connected to the connection point 15 for the line terminal 10. The blowout coil 44 is similarly connected between the arc runner 41 and the connection point 16 for the load terminal 11. Thus, the arc runners 22, 23 and the arc runners 40, 41 are connected electrically in parallel through their blowout coils 30, 31 and 43, 44.

The structure of the arc chutes of the main circuit breaker 12 and arc extinguishing device 14 is more fully shown in FIGURE 2 wherein it can be seen that a conduit 45 extends between the pressure chamber 29 of the main circuit breaker and the pressure chamber 39 of the arc extinguishing device 14. The rear walls 46, 47 of the main circuit breaker 12 and are extinguishing device 14, respectively, are also shown and can be seen to support the arc cooling fins 35 and 42. In addition to the rear walls 46, 47, the arc chutes are also provided with front walls 48, 49 as seen in FIGURE 3 to form substantially complete enclosures for the arcs therein.

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 4 normally pass through the main circuit breaker 12. 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 to move the movable contact member 24 in the opening direction (i.e. to the position shown in FIGURE 1).

As the movable contact member 24 moves towards the open circuit position, two short arcs are drawn between the contact faces 20, 26 and 21, 27 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 contacts 20, 21 rapidly moves out along the diverging arc runners 22, 23 as the pressure in the chamber 29 increases due to the heating action on the gaseous atmosphere produced by the arc.

A portion of the gaseous atmosphere containing charged particles flows through the conduit 45 into the pressure chamber of the arc interrupting device 14 under the influence of the pressure in the chamber 29 so as to produce an atmosphere of charged particles within the arc chute 37. When sufiicient charged particles have been transported into the arc chute 37 so as to lower the breakdown value between the arc runners 40, 41, to a point lower than the potential built up by the arc traveling outwardly along the arc runners 22, 23, an arc will be drawn in the arc chute 37 and current will flow therethrough. Since the high voltage drop now existing between the arc runners 22, 23 of the main circuit breaker 12 is in excess of that between the arc runners 40, 41 at the point where the arc is initially drawn, transfer .of current to the arc chute 37 occurs, resulting in the extinguishing of the arc in the main circuit breaker 12.

It will be appreciated that the arc between the arc runners 40, 41 will similarly move outwardly and increase in length so that its voltage drop will also increase. The are generated by the short circuit current may thus be accommodated in the arc extinguishing devices without damage thereto until such time as the alternating current reaches the null point and the arc is extinguished. In using three or more are extinguishing devices connected in sequence, the ionized particles from the first arc chute will be conducted to the second arc chute to draw the arc therein as described above. As the arc flows in the second device, charged particles from it will cause a sufl'icient lowering of the breakdown potential in the third device so as to cause the arc to be drawn therein, etc. Since the arc extinguishing devices are relatively compact units, it is quite feasible to arrange a multiplicity of these units in sequence connected by suitable gas conduits so as to handle very high short circuit currents.

Thus, it can be seen that the circuit interrupting device provides a novel means for effecting arc dissipation and may be readily 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.

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

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

1. A current interrupting device comprising:

(a) a support;

(b) a first pair of elongated diverging arc runners supported on said support, said are runners comprising a pair of closely-spaced end portions defining a space therebetween and a pair of widely-spaced end portions;

(c) means for creating an electric are between said first pair of arc runners at said closely-spaced end portions;

(d) means for moving said are outwardly along said first pair of arc runners from said closely-spaced end portions toward said widely-spaced end portions;

(e) a second pair of elongated diverging arc runners supported adjacent said first pair of arc runners, said second pair of arc runners comprising a pair of closely-spaced end portions defining a space therebetween and a pair of widely-spaced end portions;

(f) means connecting said second pair of arc runners electrically in parallel with said first pair of arc runners to form a second current path in parallel with a first current path including said first pair of are runners;

(g) conduit means extending from said space between said closely-spaced end portions of said first arc runners to said space between said closely-spaced end portions of said second arc runners, whereby at least a portion ionized gases generated in said space between said first arc runners upon the occurrence of an are between said closely-spaced portions of said first arc runners flow through said conduit to said space between said closely-spaced end portions of said second arc runners to initiate electrical breakdown between said second arc-runners upon build-up of arc voltage between said first arc runners and transfer of current from said current path including said first pair of arc runners and transfer of current fom said first path to said second path.

2. A current interrupting device as set forth in claim 1,

said device including insulating means separately enclosing each of said first and second pairs of arc runners.

3. A current interrupting device as set forth in claim 1,

said device also including:

(a) a pair of stationary contacts carried by said closelyspaced end portions of said first pair of are runners respectively;

(b) a bridging contact member;

(c) means carried by said support supporting said movable contact member for movement into and out of engagement with said stationary contacts to initiate an arc therebetween.

4. A current interrupting device as set forth in claim 2,

10 said device also including at least one of said first and second pairs of arc runners.

5. A current interrupting device as set forth in claim 2 wherein said conduit means comprises an elongated tubular member.

References Cited UNITED STATES PATENTS 1,819,207 8/1931 Slepian 200-144 2,508,954 5/1950 Latour et a1. 313306 X 2,900,566 8/1959 Fischer 31536 3,093,766 6/1963 Cobine 313-306 X 3,436,597 4/1969 Hurtle 31711 FOREIGN PATENTS 25,287 12/ 1905 Great Britain. 991,926 5/ 1965 Great Britain. 199,715 12/1965 Sweden.

ROBERT S. MACON, Primary Examiner ROBERT A. VANDERHYDE, Assistant Examiner U.S. Cl. X.R. 200145, 147

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