US 3670123 A
A vacuum switch has means for selectively opening or closing one or more of plural contact sets each having a stationary contact and a relatively movable contact. Terminals for the stationary contacts are provided within an electrically dead tank which provides the vacuum enclosure for the contacts and also for terminal conductors.
Claims available in
Description (OCR text may contain errors)
United States Patent Luehring 1451 June 13, 1972 MULTI-POINT TO COMMON POINT erences Cited DEAD TANK SWITCH HAVING U I STATES PATENTS VACUUM INSULATED CONTACTS AND 2,906,841 9/1959 Jennings ..200/ 144 B VACUUM INSULATED TERMINALS 3,305,657 2/1967 Roxburgh et al. ..200/144 13  Inventor: 51:11:21- L. Luehring, Cleveland Heights, I FOREIGN PATENTS OR APPLICATIONS 1 1,372,239 8/1964 France .200/144 B  Ass1gnee: Joslyn Mfg. and Supply Company, v
Chicago Primary Examiner-Robert S. Macon  Filed: April 29 7 Attorney -Richard MacCutcheon 21 Appl. No.: 138,562 57 ABSTRACT A vacuum switch has means for selectively opening or closing [521 US. Cl ..200/144 B, 200/145 4 one o more of plural contact sets each having a stationary 511 1111. c1. ..H01h 33/66 Contact and a relatively movable Contact Terminals for the 581 Field of Search ..20o/144 B, 145 R Stationary Contacts are Provided Within an electrically dead.
tank which provides the vacuum enclosure for the contacts and also for terminal conductors.
4 Clains, 5 Drawing Figures PATENTEDJUH 13 1272 SHEET 2 OF 3 INVENTOR.
ELMER L. LUEHRING ATTORNEY PATENTEDJUH 13 1212 3,870,123
sum 3 0F 3 INVENTOR.
ELMER L. LUEHRING ATTORNEY BACKGROUND OF THE INVENTION The present application relates to high voltage power switch-gear and is believed to have particular significance in connection with that type of switch which uses high vacuum as insulation. However, the invention can also have utility in connection with switches having fluid (e.g., oil or a gas other than air) insulation.
While there may be unsuccessful exceptions, heretofore, vacuum switches capable of interrupting high currents (e.g., above 100 amperes) at high rms voltage (e.g., above I KV) have typically been two-terminal devices. Each such device has had its own (usually insulating material) enclosure for a single pair of separable contacts. Conventionally, a metal condensing shield is included within the (e.g., evacuated) insulating material envelope and one of the contact members is movable through a bellows. Such a switch is difficult to enclose to be safe from accidental environmental interferences, pollutants, rain-wetting, and, particularly, water immersion.
Although many prior attempts have been made to provide a dead-tank (e.g., an electrical-ground-surfaced) vacuum switch, the prototypes heretofore have failed, primarily because of conduction to ground during interruption.
An object of the present invention is to provide simple and inexpensive means for overcoming the abovementioned difficulties.
BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages will become apparent and the invention may be better understood from consideration of the following description taken in connection with the accompanying drawings, in which:
FIG. I is a simplified schematic diagram for describing, as a preferred embodiment of the invention, a three point/common point (or three-way) switch;
FIG. 2 is an elevational view in cross-section of a vacuum switch operable for the arrangement suggested by FIG. 1;
FIG. 3 is a schematic illustration of a loop circuit wherein devices according to the invention are useful;
FIG. 4 is a simplified schematic diagram of an arrangement for selectively providing power from a normally preferred source or from an emergency source, as for a hospital; and
FIG. 5 is a cross-section taken on the line 5-5 of FIG. 2.
DESCRIPTION OF THE EMBODIMENTS In FIG. 1, dashed line block 46 represents the outline of a three-way switch having terminals 1, 2 and 3. A fourth point or part 4 is an'internal connection. Three switch gaps have stationary contacts associated with 1, 2 and 3 and have respective movable contacts 11b, 11c, 11a. Whenever contacts Ila, b and c are all open, the internal connection or terminal 4 is isolated.
In FIG. 2, like-functioning parts are like-numbered as in FIG. 1. Though the entire switch apparatus can be tilted around to operate at any angle (e.g., to provide lowermost, thus rain-shielded, line terminals) an up-side-down arrangement of a three-legged stool is somewhat analogous to the FIG. 2 showing of movable contacts Ila, b and 0 each cooperable with a common conductive material wobble plate 4.
Operating rods 21 extend through grounded lower guides 22 each sealed by its own resilient metal (or other material) bellows 23.
Each operating rod 21 cooperates through its own insulating material section 24 with an upper rod portion 25 for moving the respective contact, lla, b or 0, while the upper end of the respective bellows 23 moves and the bellows preserves the vacuum.
Means for selectively moving or wobbling the conductive plate 4 include plural universal, e.g., ball and socket, joints each preferably quite near to the point of associate contact separation. As shown, each rod section 25 terminates in a ball mating with a socket at the top of a respective movable contact support member 26 mechanically, and electrically, associated with the conductive wobble plate 4.
Plural, electrically floating, condensing shields 27, in cooperation with other baffles, serve to completely hide" the contact pairs (1 Ia-IZ, I Ib-l2, etc.) from ground, and to hide each from remote terminals. That is, the contact pair associated with terminal I is hidden from terminal 2, and from temiinal 3. A separate, preferably ceramic, insulating material shield cylinder 29L not only supports but isolates each (presumably metal) shield 27 from any foreign source of current. For example, if there is any contact metal vapor stream, it is stopped by shielding means which surrounds the particular contact set. An associate terminal lead rod 51 associates each fixed contact 12 with a respective (e.g., threaded) terminal 3, 2 or I, surrounded, respectively, by upper insulative cylinder means indicated generally as 29U.
A metallic shield cup means 52 is used to prevent metallic vapor from reaching a grounded surface out the bottom end of shield 27, and a separate metal terminal flange 53, a different one in cooperation with each of the (as shown, three) lower insulating cylinders 29L, prevents metallic vapor from reaching a grounded surface at the top end of shield 27.
As previously intimated, and later more fully explained, the switch can thus be provided with a substantially completely enclosing dead or grounded tank. The tank could take many forms but it is assumed to have a bottom plate, 558, a cylinder side wall, 55C, and a top, 5ST, with circular adapter seals 56 provided to preserve the vacuum while making a semi-flexible connection between, for example, a rigid metal tank top 5ST and preferably ceramic terminal insulation 29.
For operation, all control rods 21 could be pulled to opened position simultaneously, but that is only occasionally contemplated. Instead, as just one rod, such as that associated with contact 11a, is pulled, the wobble plate 4 pivots about a line through the mating points of the other contacts, 11b and 1 1c.
It is not necessary that there be a three-legged arrangement. There might be only two legs (outside terminals) or (for standardization and for ease of making connections) there could be three legs with the contacts of one leg always held closed (as by a spring means) as might be found useful for the arrangements about to be described in connection with FIGS. 3 and 4.
FIG. 3 is a one-line diagram of a loop system 31, 32, 33 such as might be used for underground distribution of energy from a source 34. Each tap, such as 35 from the loop as to a residence or transformer, requires a similar switch having at least two breaks (switch gaps) associated with a common point. For each such tap, the three-gap switch of FIG. 2 can be employed or there might be a two-gap switch at each such location and still it would in no-wise escape the scope of the present invention so far as the prior art permits.
FIG. 4 illustrates application of a two (or three) gap common point switch for switching between an ordinarily preferred power source 41 and an emergency source 42, as for supplying a hospital or large public building, represented in the schematic merely by the transformer symbol 43. In any event, and whether the switching is automatic (e.g.,' by preferred source voltage sensing) or manual, the switch gap 44 would be normally closed and switch gap 45 would be normally open while switch 44 would open and switch 45 close if preferred source voltage is lost at the load, or ahead of the load if an automatic transfer back is desired.
SUMMARY OF OPERATION AND ADVANTAGES There is thus provided apparatus of the class described providing many advantages.
In considering actual operation, and referring to FIG. 2 as an example, suppose that the contact pairs are all closed, and
that it is desired to open contact pair 1 10-12 and that its opening starts. As contact 1 la is moved to open position (e.g., fullopen being a A-inch gap), the conductive plate 4 and all parts rigidly connected to it will revolve substantially about a line through mating points of contacts 11b and 110. Any arc products from contacts Ila-l2 move away from the contacts and condense on associate shield 27. 7
With the assumed sequence of operation, of contact pair Ila-12 opening while the other contact pairs are closed,-arcing is preferential between contact 11a and 12. Associate shield 27 is conductively isolated from any other source of current by insulator shield 29. Thus; there will be no arcing to metal shield 27, and no current will flow through it, because -two arcs in series would be required to maintain a circuit through 27. With the equilateral spacing assumed (see FIG. 5), two arcs in series would require a greater voltage than the single are at contact gap and the two arcs cannot start because preceded by the single arc path.
This affords a novel switch design wherein not only open gap insulation but also terminal-to-terminal (or conductor) and also contact-to-ground insulation comprises high vacuum, or some inert fluid if that be desired. There is thus provided a switch design useful even in submersible applications wherein the outside of the switch is at ground potential and whereby electrical connection may readily be made from concentric neutral cables (not shown) with solid insulation so as to completely contain the electric field.
And there is provided a versatile switch of simple design having three (or two, or any plural number of) terminals capable of use for switching branch circuits and loop circuits within common vacuum chamber means.
Arrangements according to the invention can have other uses than those described. For example, with simultaneous operation of operating rods, a plural-break switch can be achieved for series application to raise the operating voltage rating of a single enclosure, and this may be possible primarily because of present invention novelty in isolating the (as disclosed, inner) shield for any contact set from that of any other tended to be defined only by the appended claims taken with all reasonable equivalents.
I claim: 1. In a high voltage electrical switch, the combination of an outer tank means which forms a substantially single enclosure protected against ambient and for containing substantially no air, plural contact sets located within the tank means and each comprising a relatively stationary contact and a relatively movable contact, plural operating rods at least partly insulative and arranged forselectively moving each of the movable contacts each selectively independent of position or movement of any other, an internal common member electrically in circuit with all movable contacts, plural terminal connectors each associated with a respective one of the stationary contacts, plural shielding means each spacingly surrounding a respective stationary contact with said shielding means being electrically isolated each from the other. 2. In a high voltage switch, the combination of claim further characterized by the internal common connection member being plate-like,
and there being movable contact support members which interconnect the operating rods with the movable contacts and with the internal common connection member through universal joints. 3. In a high voltage switch, the combination of claim 1 further characterized by the switch being a plural way to common point vacuum