US3551626A - Fluid-blast circuit interrupters with improved electromagnetic driving means - Google Patents

Description

United States Patent 72] Inventor Stanislaw A. Milianowicz Monroeville, Pa. [2]] Appl. No. 616,544 [22] Filed Feb. 16, 1967 [45] Patented Dec. 29,1970 [73] Assignee Westinghouse Electric Corporation Pittsburgh, Pa. a corporation of Pennsylvania [54] FLUID-BLAST CIRCUIT INTERRUPTERS WITH IMPROVED ELECTROMAGNETIC DRIVING MEANS 8 Claims, 10 Drawing Figs.

[52] U.S. Cl 200/148, 335/71, 335/201, 200/150 [51] Int. Cl H01h 33/70 [50] Field of Search 200/ 148; 335/71, 201; 3l7/(Inquired); 200/147, 1500 [5 6] References Cited UNITED STATES PATENTS 2,381,244 8/1945 Arnold ZOO/150 2,897,408 7/l959 Kesselring et al 317/60 3,268,687 8/1966 Waghorne et al.... 335/71 3,315,056 4/1967 Furukawa et al. 200/148 FOREIGN PATENTS 1,142,201 1/1963 Germany 200/148 1,190,079 4/1965 Germany 200/148 1,206,056 12/1965 Germany 200/148 514,359 0/1938 Great Britain ZOO/148.1

Primary Examiner-Robert S. Macon Attorneys-A. T. Stratton, C, L. Mc Hale and W. R. Crout L- (LL/ll 11/11 /77\ O) PATENTED [152291970 SHEET 1 OF 3 OPERA MECHA INVENTOR Sfumslow A. Milionowicz BY MM Q "M ATTORNEY FLUID-BLAST CIRCUIT INTERRUPTERS WITH IMPROVED ELECTROMAGNETIC DRIVING MEANS CROSS-REFERENCES TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION This invention relates, generally, to fluid-blast circuit interrupters and, more particularly, to improved fluid-blast circuit interrupters having electromagnetic fluid-driving means associated therewith.

In U.S. Pat. application (W.E. 38,481) tiled Sept. 1, I966, Ser. No. 576,739, by Russell E. Frink, and assigned to the assignee of the instant application, there is illustrated .and described a novel fluid-blast circuit interrupter utilizing electromagnetic means including a pair of accelerating coils connected electrically into the circuit by means of arc-horn means during the opening operation of the interrupter. The structure functions in such a manner so as to force the fault current to flow through the two accelerating coils thereby generating magnetic fields thereabout, which attract each other to thereby assist the piston means in forcing fluid to effect are extinction.

SUMMARY or THE INVENTION It is a general object of the present invention to improve upon the general type of fluid-blast circuit interrupter of the having inductive coupling therebetween, only one of which is electrically connected into the current path during the opening operation, whereas the other is short-circuited permitting aforesaid application by utilizing a pair of coils, only one of the flow of magnetically induced current therein to provide a repulsion force between the coils for providing accelerated fluid piston flow. v i

Still a further object of the present invention is to provide an improved fluid-blast circuit interrupter utilizing electromagnetic means to assist piston actuation in which all contacts of the secondary coil or coils are eliminated, and the structure is of simplified construction.

According to a preferredembodiment of the invention, there is provided an enclosed interrupting chamber containing a suitable arc-extinguishing gas, such as sulfur-hexafluoride (SF6) gas. Disposed within the chamber is an operating cylinder, within which reciprocally moves a piston structure carrying the movable contact structure and a moving coil. By means of an arcing horn, which is insulated from the main contact structure and is electrically connected to the moving coil, the device functions so that there occurs arc transfer, during the opening operation, to the arcing horn, which inserts the moving coil electrically into the series circuit. Surrounding the operating cylinder is a fixed coil, of a single or multiturn design, which is short-circuited. Because of the inductive coupling betweenthe coils, there is a magnetically induced current flow through the stationary coil, which provides a force of repulsion, and thereby assists the opening fluid-driving motion of the piston member, which carries the moving series coil. t

According to another embodiment of theinvention, there is provided a fluid-flow circuit interrupter including an operating cylinder, within which moves a metallic-floating piston, which cooperates with a moving piston mechanically driven and carrying a moving series coil. Additionally, on the outside of the operating cylinder there is provided a fixed single tum coil and a pair of series-connected single-tum coils, which, through their inductive coupling with the moving coil secured to the aforesaid fluid-driving piston, result in both piston members moving toward each other for accelerated fluid-driv ing action.

In accordance with another embodiment of the present invention, there is provided a fluid-driving piston carrying a moving coil and moving contact structure, with an arcing horn so arranged as to send the series current through the moving coil. The operating cylinder, within which the moving piston reciprocates, comprises a continuous conducting metallic portion and a noncontinuous portion remote from the closed position of the piston assembly. During the opening operation, the series fault current is forced to flow through the moving coil carried by the piston, and due to theinductive coupling, the continuous metallic walls of the operating cylinder have current induced therein, which acts to repel the moving coil and thereby accelerate the fluid-driving motion of the piston.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings.

BRIEF DESCRIPTION OF TI-IE DRAWINGS FIG. 1 is a vertical sectional view, partially in side elevation, of a fluid-blast type of circuit interrupter incorporating the principles of the present invention, the contact structure being illustrated in the closed-circuit position;

FIG. 2 is a considerably enlarged vertical sectional view taken through the interrupting structure of the circuit interrupter illustrated in FIG. 1, again the contact structure being illustrated in the closed-circuit position;

FIG. 3 is a view similar to that of FIG. 2, but showing arc establishment during the opening operation of the interrupter;

FIG. 4 is a graph of the current peak and force peak envelopes for a pair of inductively coupled coils;

FIG. 5 is a similar graph for a different coil construction;

FIG. 6 is a vertical sectional view taken through a modified form .of the invention in which a metallic-floating piston member cooperates with the mechanically driven piston member through a series-coil arrangement to provide accelerated fluid-driving action, the contact structure being illustrated in the closed-circuit position;

FIG. 6A is a diagrammatic view indicating the coil arrangement of the construction illustrated in FIG. 6;

FIG. 7 is a view similar to view 6, but illustrating the position of the several parts during the opening operation;

FIG. 8 is a vertical sectional view taken through a further modified form of the invention, the contact structure being illustrated in the closed-circuit position; and

FIG. 9 is a view similar to that of FIG. 8, but illustrating the position'of the several parts during the opening operation. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a fluidblast type of circuit interrupter. Generally, the fluid-blast circuit interrupter 1 includes a top line terminal casting 2, an upstanding insulating casing 3, of some suitable weatherproof material, such as porcelain, and a lower mechanism casing 4. As well-known by those skilled in the art, the several casings may have flanged bolted connectionsto secure them together, as shown in FIG. 1. The casing contains, preferably, an ambient gas pressure of the order of 60 p.s.i. of sulfur-hexafluroide (SF,,) gas, for example. Of course, other suitable arcextinguishing gases at various pressures, could be used.

Extending downwardly interiorly of the upper line terminal casting 2 is a stationary tubular venting contact 5 making contacting engagement with a plurality of circumferentially disposed contact fingers 6, which are carried by a movable insulating piston member 8 reciprocally operating within an outer operating cylinder 10. The operating cylinder 10 is maintained in a stationary position within the casing 3 by having a radially outwardly extending flange portion thereof,

being bolted to a stationary support ring 11 ,the latter, in turn,

fully described hereinafter, the fluid-moving piston member 8 reciprocally operates within the stationary operating cylinder 10 to compress a suitable fluid 13, such as sulfur-hexafluoride (SF,,) gas, within the region 14 below the movable piston member 8, and force the compressed SF gas into the established are 15 to effect its extinction.

As shown in FIG. 1, the movable piston assembly 8 is mechanically connected to a conducting piston and contact rod 17, which extends through an opening 18. in the base 19 of the stationary operating cylinder 10, and is pivotally connected, as at 20, to a floating link 21, the latter, in turn, being pivotallyconnected, as at 22, to a rotating arm 23 fixedly secured to a rotatable drive shaft 24. The drive shaft 24 extends through a seal 25 externally of the casing 4, and has an external crank-arm 26, the latter being connected to an operating mechanism, generally designated by the reference numeral 27.

As is obvious from an inspection of FIG. 1, operation of the operating mechanism 27 will effect either opening or closing rotative movement of the rotatable drive shaft 24, which in turn, will effect opening and closing vertical movement of the piston, or contact rod 17. Y Y

With reference to FIGS. 2 and 3 of the drawings, it will be noted that a connection 30 is provided between the movable arcing horn 31 and one terminal 32 ofthe moving coil 33. The other terminal 34 of the moving coil 33 is electrically connected by a connection 29 by brazing 36, to the contact rod 17.

Surrounding the stationary operating cylinder 10 is a fixed coil 37, which may be of single, or multiturn design, which is short-circuited. As a result, the inductivecoupling between the coils 33, 37 permits the flow of magnetically induced currentto flow in the stationary coil 37, which will produce a force of repulsion between the two coils, which is used to assist piston motion 8 as shown in FIG. 3. Such an arrangement is particularly desirable during fault-current interruption in which-back pressure caused by the are. 15, would otherwise necessitate a powerful operating mechanism 27.

Existing magnetic puffers, of the type set forth in the aforesaid Frink patent application, utilize coil arrangements where all the coils form a part of the current path through the interrupter. The present invention proposes the use of inductive coupling i.e. one coil 33 in the current path, and the other short-circuited permitting the flowof magnetically induced current therein. Such pair of coils 33, 37 will produce a force of repulsion, which assists the pistons motion 8,, and consequently enables the use of a low-power operating mechanism 27.

As shown in FIGS. 2 and 3, the gas pressure generated below the piston assembly 8 is forced up through apertures 38 provided therein and through an insulating nozzle member 39 to cause arc transfer to the arcing horn 31. This effects electrical connection intothe circuit of the moving coil 33, and provides the required repulsion action. 7

The flow of current in the fixed coil 37 results due to the in duced e.m.f. therein because of the, changing flux of the moving coil 33. The force of repulsion between the coils 33, 37 will be proportional to the mutual inductance of the two coils,

and will be quite significant throughout the opening stroke of travel. 7

An important advantage of the present invention in utilizing a short-circuited coil 37 is the elimination of sliding contacts, which are unavoidable in arrangements of magnetic puffer in which all of the coils are inserted into the series electrical circuit.

CALCULATIONS Calculations were performed for a current of 40,000 amcoil consisting of 12.8 inches O.D. X 9.7 inches I.D. X 2 inc hes 7 long, 10 turns supplied by 40,000 amperes r.m.s. The secondary coil is assumed to be 16 inches O.'D. X 14 inches l.D. X12 inches long and to consist of a single-tum short-circuited. The reference numeral 41 in FIG. 4 illustrates the peak force of repulsion between the two coils, with the curves 42 and 43 indicating, respectively, the peak currents through the coils.

For another set of coil dimensions, calculations result in the graphical representation, as illustrated in FIG. 5. In this case, the current peak and force-peak envelopes for a pair of inductively coupled coils are illustrated. In this case, the primary coil consists of 12.5 inches O.D. X 10.5 inches l.D. X 2 inches long, and consisting of 10 turns supplied by 40,000 amperes r.m.s. Also, the secondary coil consists of 15.75 inches O.D. X 13.75 inches I.D. X 2 inches long, and consisting of a single turn, which is short-circuited. The reference numerals 45, 46 and 47 respectively, indicate the repulsion force, and the currents through the respective coils, as illustrated in FIG. 5 of the drawings.

FIGS. 6, 6A and 7 illustrate a modification of the invention in which a metallic-floating piston 50 is provided, which cooperates with the movable fluid-driving piston assembly 8. This results in a more rapid compression of the fluid within the space 14 below the piston 8 for accelerated fluid-driving action. In the circuit-interrupting arrangement 51 of FIGS. 6 and 7, it will be noted that there is provided a moving coil 33 electrically connected into the series circuit as was the case in FIGS. l-3, but, additionally, there is provided a fixed coil 37 and a pair of serially connected coils 52, 53, which are electrically connected in series, as more clearly illustrated in FIG. 6A of the drawings.

A resetting spring 54 is provided to initially locate the floating piston 50 at the lower end of the operating cylinder 56, as illustrated in FIG. 6 of the drawings. During the opening operation, as illustrated in FIG. 7, the moving coil 33 has the series current transferred therethrough, and this inductively causes current to flow in the fixed short-circuited coil 37. The addition of the two series coils 52, 53 results in a repulsion action forcing the metallic-floating piston 50, which constitutes a short-circuited turn, upwardly within the operating cylinder 56 to provide additional fluid pressure, as illustrated in FIG. 7 of the drawings.

In more detail, the current induced in the top fixed coil 52 of the two series-connected coils 52, 53 flows through the lower coil 53. This lower coil 53 acts as primary to the metallic-floating piston 50, which acts as a single-tum short-circuited coil. The floating piston 50 is located inside the cylinder 56 and near the lower end, being spring-loaded lightly in a downward direction in order to return to the bottom of the operating cylinder 56. When current flows through the lower fixed series coil 53, it induces a current in the metallicfloating piston 50, and a repulsionforce is produced, which accelerates the floating piston 50 upwardly. This action increases the rate at which the gas in the cylinder 56 is being compressed, as well as imparting extra energy to the gas. The result is a higher pressure occurring earlier in the opening operation of the interrupter 51, which can be utilized either as an improvement in the interrupting performance, or as a means of reducing the mechanical energy requirement for an interrupter of fixed capacity.

FIGS. 8 and 9 illustrate a further modified form of the invention in which the repulsion force is a function of the axial distance between the fixed and moving coils, and will be increased by having a portion of the upper walls of the operating cylinder being continuous, so asto function as a short-circuited turn. In other words, it will be observed that the repulsion force, described in the circuit interrupter of FIGS. l-3, is a function of the axial distance between the fixed and moving coils and will be decreasing toward the end of the opening stroke of the interrupter. This effect, as is encountered in the circuit interrupter of FIGS. 1 and 2, can be counteracted by approximate design of the fixed coil to work with a moving coil of comparatively small cross section. By making the cross section of the fixed coil nonuniform radially and axially, a large variety of force patterns can be obtained. For different positions of the moving coil along the axis of the fixed coil, it should be noted that the magnitude of the force would depend upon the rate of change of primary current, the geometry of the coils and also on the electrical conductivity of material used for the secondary coil.

As shownin FIGS. 8 and 9, a simple case of many possible variations may be used in which the fixed coil is radially uniform but axially long. A radial cut57 filled with insulation 58 is used. The axial center of the fixed coil 60 is positioned so that it will be above" the axial center of the moving coil, when the moving coil is permitted to. carry the interrupter short circuit current i.e. when current is transferred to the arcing horn 31. This will produce a downward force upon the piston 8. The magnitude of this force will not be at first very large, but as the moving coil 33 moves downwardly, it will keep on increasing as more and more of the fixed coil section 60 finds itself above the axial center of the moving coil 33. This force will become largest when the moving coil 33 reaches the lower end of the fixed coil 60. in this manner, it is possible to have a travel-force characteristic where the force increases as the moving coil 33 moves along the breaker stroke toward the low open position, as illustrated in FIG. 9. This characteristic is opposite to that arising from the arrangement illustrated in FIGS. 1 and 2, where the force always decreases as the piston moves downwardly along the operating cylinder during the breaker-opening stroke.

The forces discussed hereinabove areaxial forces, which I are used to propel piston motion 8, which compresses the gas within the cylinder 62. There are also radial forces in all of the arrangements described, but these cannot be utilized within' including a stationary contact and a cooperable movable contact structure separable to establish a main current arc, said movable contact structure including a main movable contact and a movable arcing contact insulated from said main movable contact, fluid-forcing means including piston means comprising an operating cylinder member and a piston member relatively movable with respect to each other, said movable contact structure being carried by one of said relatively movable members, electromagnetic means for assisting in the fluid-driving motion of said piston means comprising at least one accelerating coil movable with said one relatively movable member and electrically connected to said movable arcing contact, a coil including one or more short-circuited turns inductively coupled to said movable accelerating coil for repelling said movable accelerating coil and so assisting piston action, whereby the higher currents are more easily interrupted.

2. The combination of claim 1, wherein the piston member is movable within a relatively stationary operating cylinder member, and a the piston member carries the accelerating coil therewith.

3. The combination of claim 2, wherein the movable piston member carries an orifice structure to direct fluid against the a main current are.

metallic piston member moves within the operatin cylinder member, a pair of series COllS are provided externa ly of the operating cylinder member, one coil adjacent the short-circuited winding and the other serving as a primary winding for the floating metallic piston member, whereby the two pistons move toward each other for rapid fluid compression.

8. The combination according to claim 1, wherein the shortcircuited coil comprises a portion of the operating cylinder member.

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