US2047000A - Electrical connecter unit for metal clad switch gears - Google Patents

Description

July 1936- F. v. CALVERT 2,047,000-

ELECTRICAL CONNECTER UNIT FOR METAL CLAD SWITCH GEARS Filed Feb. 24, 1931 Invent or: Francis \K Calvert.

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Patented July 7, 1936 UNITED STATES PATENT OFFICE METAL CLAD SWITCH GEARS Francis V. Calvert, Lakewood, Ohio, assignor to General Electric Company, a corporation of New York Application February 24, 1931, Serial No. 517,758

Claims.

My invention relates to electrical connections for high tension metal clad switchgear, more particularly to a connecter unit as an article of manufacture serving as a self-contained jumper or D the like between metallic housings containing electrical apparatus.

Assembly in the field of outdoor metal clad bus and switch stations necessitates that the various parts be in condition to be readily placed in operating position without special treatment. Otherwise, the cost becomes excessive since skilled workmen must work under unfavorable conditions, and also the highest quality of work is not assured. For example, the electrical connections or jumpers between the metal enclosed units of the station, as oil circuit breakers, disconnecting switches, etc., are generally oil filled or of the solid insulation cable type, depending on the voltage used, and need to be very carefully insulated and prepared due to the possibility of failure of the insulation between the conductor and the outer enclosing metal sheathing of the connecter.

' The treatment of these connecters prior to use interior of the connecter during assembly. It is a well known fact that moisture causes deterioration of the type of insulation used in the present case. The moisture together with any accumulation of air or gas in the connecter tend to cause failure of the insulation at the point afiected. Even in a carefully prepared and sealed cable there is a possibility that a bubble or so of air or gas may form within the oil-filled interior and eventually cause trouble if not removed.

A principal object of my invention is the provision of an improved self-contained, oil-filled or insulated jumper or connecter unit, as an article of manufacture, hermetically sealed with respect to the electrical apparatus interconnected thereby and which may be readily mounted in operative position without special preparation.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is a fragmentary, elevational View, partly in section, of metal clad switchgear embodying my invention; Fig. 2 is a similar view of a modification illustrating the application of my invention to high voltages; Fig. 3 is an enlarged detailed View, partly in section, of an end bushing shown in Fig. 2, and Fig. 4 is an enlarged cross sectional view taken along the line 4--4 of Fig. 3.

In accordance with my invention, there is provided as illustrated in Fig. 1, a self-contained connecter unit or jumper l interconnecting electrical apparatus within the metal housings 2 and 3. As previously indicated, the electrical apparatus within the housings may comprise an oil circuit breaker as partly illustrated at 4, and other associated switchgear. The jumper l forming an article of manufacture comprises in the present instance an outer rigid metallic sheathing 5 of non-magnetic material for example, having flanges 6 at its opposite ends secured to the housings 2 and 3, and a copper conductor 1 of suitable current-carrying capacity provided with insulation 8 and extending centrally through the sheathing 5. The securing flanges 6 likewise serve to ground the sheathing 5 through the housings 2 and 3. At the points of entrance to the housings 2 and 3 the jumper also comprises the sealing insulating bushings 9 and I0 through which the conductor 1 extends. The outer ends of the conductor I are suitably connected to the flexible leads H and I2, which in turn are connected to the apparatus within the housings.

At one end of the jumper the insulating bushing 9 is rigidly mounted at 9' to the sheathing 5, the conductor I likewise being suitably sealed to the outer end of the insulator, thereby entirely sealing that end of the connection.

Prior to complete sealing of the connection, the insulating material surrounding the conductor 1 and the entire interior of the sheathing 5 are suitably treated, as by evacuation and drying, to remove all traces of moisture so that danger of insulation breakdown is minimized.

The opposite end of the connection is provided with a resilient or flexible mounting for the insulator l0 for the purpose of preventing fracture of the comparatively brittle insulating bushings in the event that one housing settles a certain amount with respect to the other housing, and to compensate for cyclic expansion and contraction of the conductor. In the present instance this resilient mounting comprises a metallic bellows or sylphon l3 suitably connected at its opposite ends, as by welding, to an annular abutment M of the sheathing 5 and a metallic sleeve H5 in turn secured, as by cement, to the insulator ill. It will, therefore, be apparent that the insulator i0 is in floating relation to the rigid housing 3 and that the sylphon i3 prevents fracture of either of the insulating bushings due to slight relative movement of the housings 2 and 3. The sealing of the insulator i0 is completed by the end cap it through which the conductor l extends to connect with the flexible conductor H2 in turn connected to one terminal of the oil circuit breaker d.

Although my invention is not limited to a horizontal arrangement of the jumper or connecter unit, the same is illustrated as being comparatively simple in construction and assembly. In this arrangement the insulating bushings instead of entering the housings through. the top, thereby necessitating looped connections, enter through the sides thereof through the removable plates H and I8 suitably bolted to the housings. The jumper may therefore serve as a disconnecting device between electrical apparatus in the metal clad housings by simply unbolting the plates i! and I8 and connections, and lifting the jumper from position. When serving particularly as a disconnecting device the jumper may be electrically connected in any suitable manner, as by sliding connections, with the associated apparatus and the disconnecting operation performed by either raising or lowering the jumper.

For the purpose of adequately insulating the conductor 1 from the sheathing 5 the annular space l9 between the conductor and the sheathing is filled with suitable insulating oil which is 5 maintained at suitable pressure during variation down.

A metallic shield may be applied over the insulation 8 between the terminals when it is desirable to remove electric stress on the oil within the sheathing.

In Fig. 2 there is illustrated a modification of my invention particularly adapted for high tension circuits. In this arrangement the housings 2 and 3 are interconnected by a jumper or connecter unit 22 comprising a high tension cable of the type commonly used for underground conductors. The unit 22 is provided with the insulating bushings 23 and 24 mounted within the corresponding housings 2 and3, and is supported at intermediate portions by the members 25 carried by the adjustable cross bar 26 secured to the housings. The supporting cross bar 26 is adjustable, as by the bolt and slot connection 21, so that inequalities in the relative positions of the housings 2 and 3 are provided for.

As in the previous instance the unit is horizontally positioned with respect to the housings so that it may readilyfunction as a disconnecting device in the manner above described, and the cable by reason of its flexibility is somewhat lower at the central portion thereof. Accordingly, any accumulation'of air or gas within the aoazooo cable would tend to rise and follow the cable to the opposite ends of the insulating bushings. For the purpose of removing air or gas bubbles from the end bushings and cable where insulation breakdown might occur, the oil reservoir 20, which is supported by the framework 28 on the cross bar 26 is in communication through the oil pipes 29 and 30 with the terminals of the unit. Referring more particularly to Figs. 3 and 4, a suitable construction of the cable and connection to the end bushings are indicated. The cable extends through and is connected to a conical sleeve 3i suitably clamped as at 32 to the removable plate 33 of the corresponding housing. The seal between the cable and the member 3| comprises a wiped connection 34 and the interior of the sleeve 3! is in communication with the reservoir 20 through the pipe 29. The insulator 23 is suitably secured to the member M, as by cement, and is provided at its outer end with a 20 cap 35 through which the conductor 36 of the cable extends in sealed relation. In view of the fact that the cable end opens within the space enclosed by the insulator 23 and the sleeve 3|, it

will be apparent that any formation of air or 25 gas is free to pass from the cable into this space and from there into the pipe 29 to the reservoir.

Referring more particularly to the construction of the cable which may be of the conventional high tension type previously referred to, the cable core or conductor 36 comprising a plurality of stranded conductors is surrounded by suitable insulating material 31, as specially treated paper impregnated with oil, the structure so formed being sheathed in a lead covering 38, as is well known in the art. For the purpose of insuring that the insulating material shall be properly impregnated with the oil at the proper pressure, the interior of the sheathing is provided with spiral grooves 39 extending longitudinally of the cable and'communicating with the opposite oil chambers formed by the end bushings. Accumulation of air or gas bubbles within the cable is therefore substantially prevented and the danger of insulation breakdown from this cause is greatly decreased. It shall be understood of course that the cable above described may be chosen to satisfy the particular voltage or operating requirements. For example, the solid insulation type may be used for low and medium voltages. Likewise for the higher voltages the well known solid oil, hollow core type of cable may be used.

The connecter units illustrated in Figs. 1 and 2 p are complete as an article of manufacture before. assembly of the apparatus in the field, and hence the oil, when used, within the unit is distinct and separate from and cannot be contaminated by the oil in the housings containing the associated switchgear. Furthermore, since the units are completely sealed at the factory there is no danger It should be understood that my invention is 70 not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

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

1. As an article of manufacture, a jumper unit for detachably interconnecting high tension, metal clad switchgear having separate metal housings comprising a continuous conductor, a continuous metal sheathing surrounding and insulated from said conductor, said sheathing containing aninsulating oil, insulating terminal bushings connected to and hermetically sealing opposite ends of said sheathing, said terminal bushings being detachably connected with respect to said switchgear, and means communicating with said sheathing for supplying the same with insulating oil, said jumper and oil supply means constituting a replaceable self-contained hermetically sealed unit. I

2. A self-contained jumper unit for high tension metal clad switchgear comprising a conductor, a rigid metal sheathing surrounding and insulated from said conductor, an insulating bush ing mounted at and hermetically sealing one end of said sheathing and conductor, an insulating bushing at the opposite end of said conductor and sheathing, and a flexible sealing member interconnectingv said sheathing and insulating bushing for permitting limited relative movement between said bushings without causing fracture of the same.

3. A jumper unit for metal clad switchgear comprising a conductor, a rigid metal sheathing surrounding and spaced from said conductor, insulating oil filling said sheathing, insulating bushings mounted at the opposite ends of said "sheathing hermetically sealing the jumper unit,

' ing and mounted at the opposite ends of said cable, said bushings and cable being arranged so that the center of the cable is lower than the end bushings, and an oil reservoir mounted on said supporting structure and above said cable and communicating with said bushings so that gas formed within said cable tends to escape to the end bushings and to said reservoir thereby minimizing insulation failure.

5. As an article of manufacture, a flexible jumper unit for detachably interconnecting high tension, metal clad switchgear having separate metal housings comprising a conductor, a continuous flexible metal sheathing surrounding and insulated from said conductor, said sheathing containing an insulating oil, and insulating terminal bushings connected to and hermetically sealing opposite ends of said sheathing so that said jumper constitutes a self-contained hermetically sealed unit, said bushings being detachably connected with respect to said switchgear.

FRANCIS V. CALVERT.

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