US2915611A - Tandem vacuum switches - Google Patents

Description

Dec. 1, 1959 E. L. LUEHRING ETAL TANDEM VACUUM SWITCHES Filed Jan. 27, 1958 Fig. l

(PRIOR ART) 2 Sheets-Sheet 1 Fig. 2 (PRIOR ART) mvamons- ELMER 1.. LUEHRING BY HARRY E POE ATTORN EY 1959 E. L. LUEHRING ETAL 2,915,611

TANDEM VACUUM SWITCHES 2 Sheets-Sheet 2 Filed Jan. 27, 1958 J m/111mm ATTORNEY 2,915,611 TANDEM VACUUM SWITCHES Elmer L. Luehring and Harry E. Poe, Cleveland, Ohio,

assignors to Hi-Voltage Equipment Company, Cleveland, Ohio, a corporation of Illinois Application January 27, 1958, Serial No. 711,196 6 Claims. (Cl. 200-145) The present invention relates to tandem or series connected interrupters of the type enclosed in vacuum or immersed in a fluid other than air. The invention has particular significance in connection with high voltage polyphase power line switching apparatus of Well known type comprising main air blade switches and associate enclosed interrupters with interlocking, usually mechanical, such that the main blades will open first, while the circuit is shorted through paralleled interrupters, and that the enclosed-against-ambient interrupters will open last so that there is no destructive arcing. Any desired arrangement can be used upon closure but usually, as for a capacitor bank circuit where it is desired to avoid high inrush currents which would be destructive to the interrupters, there will be a delay of closure of the interrupters until the main blades are first closed.

Without noticeable patent activity, the art has gone forward from a single vacuum interrupter for each air switch to as many as eight vacuum interrupters in series in order to take care of the higher voltages. Thus, as shown in Figs. 1 and 2 of the accompanying drawing, it has-heretofore been known to have (for each phase) an insulating rod and tube surrounded assembly of electrically series connected vacuum interrupters. But the component parts of such an arrangement have heretofore been too fragile and delicate to ship in the assembled condition, and too complicated for ordinary workmen to assemble in the field, and it has heretofore seemed necessary to send an engineer from the home plant to assist in each erection. Furthermore, past shipments, even of separated parts, have encountered rough handling, resulting in there being nothing but a mass of broken glass and broken parts at the receiving end.

It is an object of the present invention to provide simple and inexpensive means for overcoming the above mentioned difiiculties.

In accordance with one aspect of the invention, we obviate the rod and glass tube enclosed prior art assembly by utilizing a combination of modular foam encapsulated vacuum interrupters. Thus each interrupter has its own permanent shockproof shipping container, and the final assembly may be shipped together or the principal components can be shipped separately and damage enroute will be very unlikely, and field installation will be no problem in either case. According to the invention, the modular potting material provides the means for developing a desirable electrical resistance or gradient characteristic to provide a constant voltage gradient over the length of the vacuum assembly instead of concentrating the voltage difference adjacent sharp points at one end of each vacuum interrupter when open circuited. According to another aspect of the invention, We encapsulate vacuum interrupters in a protective cellular foam and still make adequate provision for mechanical operation and for bringing out the electrical leads thereby enabling much more rapid testing of particular units of the apparatus than was ever possible with prior art arrangements.

Additional objects and further advantages will become United States Patent apparent and the invention may be better understood from consideration of the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a greatly simplified and schematic elevational view of a prior art bolted-together assembly of two individual vacuum interrupters;

Fig. 2 is a partial bottom view taken along the line 2-2 of Fig. 1;

Fig. 3 is a top view of a single modular encapsulated vacuum interrupter with protective assembly and constructed in accordance with the present invention;

Fig. 4 is a part-turned elevational section of the interrupter of Fig. 3 as viewed along the line 44, and shows a portion of another like unit to which the former is finally bolted.

In order to better understand the setting of the present invention, reference is made first to the prior art arrangement of Figs. 1 and 2 where 'a toggle frame 10 and a spring-and-actuator crank 11 are associated with toggle links 12-13 and a toggle release sear 14. When an initial signal is sent by some apparatus (not shown) the above mentioned parts combine to move a pair of insulated operating rods 15 to simultaneously operate the various vacuum interrupter units which are electrically connected in series with each other and mechanically arranged in tandem with the combination usually in parallel with a main air break switch (not shown). In Fig. 1, only two vacuum units 16, 17 are indicated in outline, but it should be understood that as many as six or even more might be arranged in series and in tandem, according to total operational voltage, as previously mentioned. It might be mentioned that there is no necessity of the units being all electrically in series. They might be connected electrically in parallel or different ones (or more electrically in series) might be operative in each of plural phases, but it is assumed that the cascaded tandem units are 'substantially (e.g., except for shipping, maintenance, testing or repair) permanently mechanically connected in series. Each interrupter need not necessarily be of vacuum type since the enclosed contacts might be immersed in an inert gas or in a liquid such as oil. Suitable inner construction is old and known to the art and not of particular importance in connection with the present invention. Something must be used to keep the vacuum interrupters apart and correctly in place. In the past it has been conventional to have an actuator mechanism base 20 with depending support pipes or rods 21 to which are clamped (as by means of set screws not detailed) interrupter support brackets such as 22 and 23. A sear release or trip rod 24 may be included, and suitable electrical connection is made between interrupters, and as shown, there may be a cable shunt 26 at the top end, and a pigtail connection 27 at the bottom end. Because the equipment is usually mounted outdoors, and thus is subjected to dirt and weathering, and because the electrical terminals operate at high potential and thus should be enclosed from a safety standpoint, it is conventional to enclose the assembled vacuum interrupters in an outer glass tube 28, and this tube usually serves to provide mechanical support for the whole apparatus.

As previously intimated, attempts to ship the entire assembled vacuum bottle interrupter apparatus often results in nothing but a mess of glass and broken parts arriving at the receiving end, while, particularly because the high voltages make the mechanical and electrical connections somewhat complex, any attempt to provide for erection in the field seems to end up in requiring the home plant to send an engineer to take care of the installation which, of course, is most uneconomical. Further difiiculties arise in that the prior art equipment provides no way to take leads (for example between units) out for tests to determine whether there are any defective interrupters and because prior an apparatus has been subject to ionization and failure due to concentration of voltage stresses at determinate points.

By contrast, apparatus according to the present inven- "tion obviates all these disadvantages, as will be seen by referring to Figs. 3 and 4. Although but one unit is shown in its entirety in Figs. 3 and 4, it should be understood that a number of like units are to be arranged in tandem, and to this end and to provide axial alignment of successive units each enclosed interrupter 16 has an outer shell of insulating material, and the annular outer shell of each of the like units is provided with a socket or groove 31 at one end and a corresponding plug or tongue 32 at the opposite end. Flange holes 33 may be provided at each end for receiving bolts 3311 (Fig. 4) for fastening together similar like units each containing a vacuum (or fluid filled) interrupter apparatus 16. Good results have been obtained using for each interrupter a vacuumized envelope having metal end caps, and separate contact rods extending into the envelope one from each cap and engaging the other rod inside a vapor shield within the envelope, with means external to the envelope for moving one of the rods relative to the other rod, and means such as a bellows interposed between the mobile rod and the envelope for preserving the vacuum of the envelope while allowing .movement of the mobile red as described, for example, in US. Patent 2,740,867 issued April 3, 1956, on an application filed by I. E. Jennings, and assigned to the Jennings Radio Manufacturing Corporation. In accordance with the present invention each of the originally enclosed interrupters, which at least ultimately are arranged in tandem, is separately encapsulated in its own somewhat resilient material permanent and shockproof container comprising a cellular foam 34. Good results have been obtained using foam 34 around and above and below the envelope of each interrupter 16 and within the annular outer housing 30, as shown in the drawing. While numerous resilient materials are available for such application, we have found that excelsior, a usual packing agent to prevent damage during shipping, is not suitable because it absorbs moisture and thus forms dangerous conducting paths. On the other hand, good results have been obtained using a material called Lockfoam commercially available in jars from the Nopco Chemical Company, Harrison, New Jersey, with labels stating that the word Lockfoam is a registered trademark of the Lockheed Aircraft Corporation and that the material is covered by one or more of Patents 2,577,279;

2,642,403. Applicants do not know the exact formulation of this material but it is said by Nopco to be a foamed-in-place plastic. It may be that the material is obtained by the reaction of polyisocyanates and resinous polymers, and it may be that as thus produced and as furnished by Lockheed and Nopco, the cells are individual rather than chain type and that therefore they are less hygroscopic, but applicants do not know this to be true and merely suggest Lockfoam and possibly other cellular materials obtained by chemical reaction as being examples of suitable non-hygroscopic, somewhat resilient (but preferably not so resilient as to be resilient to the touch) electrical resistance materials. As already explained, voltage gradient through the packing material is of importance since the packing material is to be left in place during operation to provide a result which is far superior to having a voltage difference exist through air around the vacuum interrupter envelope as has been the case according to the prior art.

As seen in Fig. 3, the foam 34 contains diametrically opposite vertical insulating material tubes 35 each containing an insulating material operating rod 36. Convenient y, the vertical tubes and the operating rods which they contain may be made of Bakelite. While each unit could have had its own operating rod extending only slightly more than the length of one encapsulated unit and provided with interconnecting threads (for accommodating rods of other units), with the arrangement contemplated in Fig. 4, the organization is otherwise and operating rod 36 is presumed installed as a long unitary member at the time of final assembly. The vertical rods 36 operate a cross bar 37 for each unit, and the cross bar is in turn connected to the mobile contact rod 38 of the interrupter itself. As shown, a flexible top lead 39 is taken out from electrical contact with the mobile contact assembly, i.e., through a notch in the end of the outer shell 30, and a stationary bottom lead 40 is taken out through the outer shell 30 from a conductive base 41. If desired, this base or bottom mounting plate 41 may mechanically hold the operating rod tube 35 with respect to the foam and with respect to the vacuum interrupter 16 and hold the vacuum interrupter with respect to the foam and thus with respect to the outer shell 30, meanwhile being electrically associated with the interrupters stationary contact rod. Similarly,

but operating at opposite electrical potential, there may be a stationary top metal disc 42.

There is thus provided an arrangement of the type described permitting either completely assembled shipment or field assembly by help with minimal experience qualifications since critical parts may be almost completely prefabricated at the factory where the greatest accuracy and economies prevail. Further, the finally assembled device, despite all the desirable ruggedizing and shockproofing, permits of easy testing for each unit at any time, permits simplified repair, and provides a desirable resistance characteristic over the length of each interrupter enclosure despite ambient conditions of humidity, storms, and leakage either during assembly or during operation.

While we have illustrated and described a particular embodiment, various modifications may obviously be made without departing from the true spirit and scope of the invention which we intend to have defined only by the appended claims taken with all reasonable equivalents.

We claim:

1. In the combination of mechanically substantially permanently tandem connected electric circuit interrupters each of the type having an envelope enclosing against ambient, the combination of separate annular housings each arranged about while spaced away from an associated one of the interrupter envelopes, with each housing constructed to interfit end for end with each like housing for each other interrupter envelope, and an en casing material extending from each annular housing inwardly to hold and protect the associate interrupter envelope.

2. For use with identical or like units, a modular enclosure of a frangible envelope enclosing a high voltage interrupter having contacts, said enclosure having a cellular foam material of the type obtained by chemical reaction and arranged about the interrupter envelope, an annular shell arranged about the foam material, interfitting end means at each end of the shell for aligning and connecting with shells of identical or like units, means traversing the foam end for end for accommodating mechanical means to operate the interrupter and electrical connection means extending out beyond the foam and out from association with the interrupter contacts through the annular shell to permit of electrical interconnection and individual test of each identical or like unit as and when such units are later assembled together.

3. For use with each of the multiple substantially permanently tandem arranged electric circuit interrupters each having conductive ends and a frangible fluid-tight casing between the ends and coaxial contacts for mating within the casing while electrically associated with the interrupter ends, the combination of a coaxial arrangement of a cellular foam arranged as a shockproof electroresistance packing around the. interrupter casing and axially extending at least co-extensive with the length of the casing, a coaxial outer shell of insulating material surrounding the foam and axially extending beyond the interrupter conductive ends, said shell being characterized by plug and socket ends for mating with other like units, means for mechanically operating the interrupter contacts from either end of the foam, and conductive means associated with the conductive ends for making electrical connections radially outside the shell.

4. For use as a modular unit interfitting end for end with other like units, a tubular outer casing having at each end thereof a radially outwardly extending flange adapted to receive circumferentially spaced means for fastening to like flanges of such other units, a mechanical shock and electrical resistant material co-axially arranged and extending radially inwardly from contact with the inside of the casing, a frangible electric circuit interrupter co-axially arranged with respect to said casing and said resistant material and radially centrally thereof and mechanically supported by said insulating material extending axially beyond and at least partially around the ends of the interrupter, means traversing the resistant material end for end while radially within the casing and outside the interrupter and for accommodating mechanical means for operating each associate interrupter from either end of any of the casings, and at each end of the interrupter electrical connection means extending radially outward to points outside of the casing.

5. For use as a modular unit, the combination as in claim 4 further characterized by the resistant material being a cellular foam.

6. For use as a high voltage disconnect, a plurality of substantially permanently end for end connected units each having a tubular outer casing, each having a shock resistant material extending inwardly from its casing, each having a coaxial frangible electric circuit interrupter radially centrally of the resistant material and supported by the resistant material extending axially beyond and radially inwardly partially around the ends of the interrupter, and mechanical means traversing all of the units end for end for operating the units mechanically in tandem from either end, and separate electrical connections extending from each end of each interrupter of each unit radially outward beyond the associate casing for connecting the units in series, in parallel, per phase or for separate test of each, as desired.

References Cited in the file of this patent UNITED STATES PATENTS 2,683,767 Cunningham June 13, 1954 2,737,579 Wehrlin et al. Mar. 6, 1956 2,810,805 Schwager Oct. 22, 1957 2,838,636 Schwager June 10, 1958 2,838,637 Schwager June 10, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,915,611 December 1, 1959 Elmer L. Luelp ring et al.

t is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below,

In the grant, lines 2 and 3, for assignors to Iii-Voltage Equipment Company, of Cleveland, Ohio, a corporation of Illinois," read assignors. to Eli-Voltage Equipment Company, of Cleveland, Ohio, a division of Joslyn Mfg. and Supply Company, a corporation of Illinois, line 12, for Hi- Voltag'e Equipment Company, its successors" read Hi-Voltage Equipment r- Company, a division of Joslyn Mfg. and Supply Company, its successors in the heading to the printed specification, lines 4 and 5, for "assignors to Iii-Voltage Equipment Company, Cleveland, Ohio, a corporation of Illinois" read assignors to TIL-Voltage Equipment Company, Cleveland, Ohio, .a division of Josly'n mg, and Supply Company, a corporation of Illinois Signed and sealed this 24th day of May 19600 I (SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON ttesting Officer Commissioner of Patents UNI'l ED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,915,611 December 1, 1959 Elmer L. Luehring et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below,

In the grant, lines 2 and 3, for "assignors to Hi -Voltage Equipment Company, of Cleveland, Ohio, a corporation of Illinois," read assignors. to Iii-Voltage Equipment Company, of Cleveland, Ohio, a division of Joslyn Mfg, and Supply Company, a corporation of Illinois, line 12, for Hi- Voltage Equipment Company, its successors" read Hi-Voltage Equipment Company, a division of Joslyn Mfg, and Supply Company, its successors in the heading to the printed specification, lines 4 and 5, for "assignors to Hi-Voltage Equipment Company, Cleveland, Ohio, a corporation of Illinois" read assignors to Iii-Voltage Equipment Company, Cleveland, Ohio, a division of Joslyn Mfg, and Supply Company, a corporation. of Illinois Signed and sealed this 24th day of May 1960.,

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents

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