US3541284A - Combined vacuum circuit interrupter and impedance means - Google Patents

Description

COMBINED VACUUM CIRCUIT INTERRUPTER AND IMPEDANCE MEANS Filed D60. 14,

Nov. 17, 1970 2. A. WACHTA 2 Sheets-Sheet 1 z. A. WACHTA 3,53,2fi

COMBINED VACUUM CIRCUIT INTERRUPTE'R AND IMPEDANCE MEANS Filed Dec. 14, 1967 2 Sheets-Sheet 2 I? w I 2 F E 1 l? 76": x V W I l Wis.

Filed Dec. 14, 1967, Ser. No. 690,597 Int. Cl. H01h 33/6'6 US. Cl. 200-144 4 Claims ABSTRACT OF THE DISCLOSURE A vacuum circuit interrupter comprising a cylindrical glass envelope having a pair of axially aligned relatively movable butt type contact rods extending thereinto is provided with impedance means comprising a pair of cylindrical metal shields which are concentrically arranged with respect to the contact rods and each other and electrically connected to respective contact rods. In one embodiment, the shields are located within the envelope and in another embodiment, the shields are located or embedded within the envelope wall. In a further embodiment, resistance means which also mechanically support the shield are connected in series circuit between each shield and its respective contact rod.

SUMMARY OF THE INVENTION In high voltage electrical systems which use series connected vacuum interrupters, more equal voltage distribution between the interrupters can be obtained by connecting impedance means, such as a resistor or capacitor, in parallel with each vacuum interrupter. Heretofore, this impedance means took the form of separate resistors or capacitors which were externally connected in parallel with each of the series connected interrupters. However, this approach resulted in the extra cost of separate cornponents and mounting means and all components were required to meet the same dielectric requirements of the interrupters themselves.

In accordance with the present invention, there is provided an interrupter, such as a vacuum interrupter, wherein impedance means, such as capacitors and resistors, occupy the same space and dielectric medium of the inter- United States Patent O rupter itself. More particularly, there is provided an interrupter having an envelope with a pair of relatively movable contact rods therein and a pair of concentrically arranged cylindrical shields within the envelope or embedded in it which surround the contact rods and are electrically connected to respective rods. In another embodiment of the invention, resistance means are located within the envelope and are connected in series with the shields.

OBJECTS It is an object of the invention to provide improved electrical circuit interrupters which have impedance means integral therewith for equalized voltage distribution.

Another object is to provide such interrupters wherein the impedance means takes the form of capacitors, resistors, or a combination of both.

Another object is to provide such interrupters which comprise an envelope in which butt type rod contacts are employed and the capacitors take the form of tubular shields which also serve to shield against the diffusion of arc products.

Another obect is to provide an interrupter of the aforesaid character wherein the resistance means in series with the tubular shields form part of the supporting structure thereof.

Other objects and advantages of the invention will hereinafter appear.

DRAWINGS The accompanying drawings illustrate several preferred embodiments of the invention, but it is to be understood that the embodiments illustrated are susceptible of modifications with respect to details thereof without departing from the scope of the appended claims.

In the drawings:

FIG. 1 is a cross sectional view of a vacuum interrupter incorporating capacitors and resistors in accordance with one embodiment of the invention;

FIG. 2 is a view taken along line l'I-II of FIG. 1;

FLIG. 3 is a cross sectional view of a vacuum interrupter incorporating capacitors in accordance with another embodiment of the invention; and

FIG. 4 is a view taken along line IVIV of FIG. 3.

DESCRIPTION OF THE INVENTION Referring to FIG. 1 of the drawing, the numeral 10 designates a high voltage vacuum type electrical circuit interrupter or switch in accordance with one embodiment of the present invention. Switch 10 comprises an envelope 12, preferably made of insulating material, such as glass, which is hermetically sealed at one end by a closure means, such as a metal cap, 14 to which a stationary butt type electrically conductive contact rod 16 is mechanically and electrically connected. Envelope 12 is hermetically sealed at its other end by a closure means 1 8 to which a movable butt type electrically conductive contact rod 20 is mechanically and electrically connected. The exterior ends of the rods 16 and 20 are understood to be adapted for connection in an appropriate electrical circuit. Closure means 18 comprises an electrically conductive ring 22 which is rigidly connected to envelope 12, an electrically conductive collar 24 which is rigidly connected to ring 22, and a bellows 26 which is connected between an annular member or washer 28 on rod 20 and an annular member or washer 30 in collar 24. Collar 24 is provided with an electrically conductive mounting flange 32. It is to be understood that bellows 26 permits axial movement of rod 20 between contact closed position (shown in FIG. 1) wherein the rods 16 and "20 butt, and contact open position (not shown) wherein the rods 16 and 20 are slightly separated.

As FIGS. 1 and 2 show in accordance with the invention, switch 10 is provided with a first electrically conductive tubular shield or member 34 which is spaced apart from and surrounds the contact rods 16 and 20 in coaxial relationship and serves as one plate or element of a capacitor. Means are provided to electrically and mechanically connect shield 34 to rod 20- and such means take the form of an electrically conductive ring or member 36. In accordance with one aspect of the invention, ring 36 could merely be made of highly conductive metal, such as copper. However, in accordance with another aspect of the invention, ring 36 could be made of material having high electrical resistance and would then serve as a resistor in series circuit with one side of the capacitance means herein described. In addition to its function as a capacitor plate, shield 34 also serves to prevent the dispersion of are products during separation of the rods 16 and 20.

Switch '10 is further provided with a second electrically conductive tubular shield or member 38 which is spaced apart from and surrounds the first shield 34 in coaxial relationship and serves as another plate or element of a capacitor. Means are provided to electrically and mechanically connect shield 38 to rod 16 and such means take the form of an electrically conductive ring or member 40.

3 Ring 40, like ring 36, could be made of highly conductive metal, such as copper, or could be made of high resistance material.

The shields 34 and 38, which are substantially coextensive with each other in the embodiment shown in FIG. 1, add substantial capacitance to the circuit when the rods 16 and 20 are energized and are in spaced apart, open circuit position. For example, the inherent capacitance of an actual switch similar to switch (but having a single shield 34 to suppress are products) was on the order of 3 micromicrofarads. Capacitance increased to about 40 micromicrofarads with the arrangement shown in FIG. 1. Further increases or decreases in capacitance would depend on the shape, spacing and area of the shields 34 and 38 and the size and shape of the rods 16 and 20.

Referring to FIG. 3 of the drawing, the numeral 50 designates another high voltage vacuum type electrical circuit interrupter or switch in accordance with another embodiment of the present invention. Switch 50 comprises a glass envelope 52 which has closure means 54 and 58 at opposite ends which are similar to the closure means 14 and 18 hereinbefore described in connection with FIG. 1. Switch 50 also has contact rods 56 and 60 similar to the contact rods 16 and 20 hereinbefore described.

As FIGS. 3 and 4 show in accordance with the present invention, switch 50 comprises first and second coaxial tubular shields 74 and 78 which, for example, are similar in size, shape and function to the shields 34 and 38 hereinbefore described. However, the shields 74 and 78 are I embedded in the wall of insulating envelope 52 of switch '50 which mechanically supports them.

The shields 74 and 78 serve as capacitance means in substantially the same manner as the shields 34 and 38 hereinbefore described. Since the shields 74 and 78 are embedded, shield 74 is not available as a condensing shield for arc products. Accordingly, a separate condensing shield 79 is provided in switch 50.

Means are provided to electrically connect the shields 74 and 78 to their respective rods and such means take the form of electrically conductive extensions 76 and 80, respectively, of the shields. However, other forms of electrical conductors or resistors could be used instead of the extensions 76 and 80.

As is apparent, switches such as 10 and 50 have the impedance means integral with switch structure itself rather than externally attached, and the dielectric integrity of the switch extends also to the impedance means. Thus, the need for separately mounted and insulated units is eliminated thereby reducing the number or; components, eliminating additional space requirements, andreducing costs.

The embodiments of the invention in which an exclu- 41 sive property or privilege is claimed are defined as follows:

1. In a vacuum interrupter,

an envelope,

a pair of relatively movable contact rods extending into said envelope and adapted to make butt' contact therein, v

' a first electrically conductive tubular capacitance mem ber surrounding portions'of both of said contact rods, first resistance means for electrically connecting said first member to one of said contact rods,

p a second electrically conductive tubular capacitance memberspaced apart from and surrounding said first member and portions of both of said contact rods, said second member being substantially coextensive with and immovable with respect to said first memb v I and second resistance means an electrically connecting said second member to the other of said contact rods,

said first and second electrically conductive tubular capacitance members and said first and second resistance means cooperating to provide impedance means in parallel with said pair of movable contacts for voltage distribution purposes,

- 2. 'A vacuum interrupter according to claim-1 wherein said'envelope is made of insulating material and said members are embedded in said envelope.

3. A vacuum interrupter according to claim 1 wherein said members are located within said envelope.

4. A vacuum interrupter according to claim 1 wherein said electrical resistance means provide mechanical support for the members with which it is in series.

References Cited UNITED STATES PATENTS 2,185,719 1/ 1940, Baker 200- 2,358,553 9/1944 Beldi. 3, 147,35 6 9/1964 Luehring -1 .200.-144.2 X r 3,185,800 5/1965 Titus 200-1442 3,43 0,015 2/ 1969 Crouch et a1. 200' 144.2 2,979,588. 4/1961 Jennings 20 0,144.2 Y FOREIGN PATENTS "693,827" 9/ 1964 Canada. 975,483 12/1961 Germany.

oB-ERT s. MACON, Primary Examiner i U.S. c1. X.R.

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