US1610903A - Insulated terminal for electrical apparatus - Google Patents

Description

Dec. 14, 1926; 1,610,903

H. TRENCHAM TNSULATED TERMINAL Eon ELECTRICAL APPARATUS Filed July 29, 1920 Invent or: Henry .Tend-lam byfw 4. M His Attorney Patented Deel 14, 1926.

' UNITED STATES Pa'rrslvr4 OFFICE,

' HENRY TRENCAM, 0F RUISLIP, ENGLAND, ASSIGNOR T GENERAL ELECTRIC COM- PANY, A CORPORATION OF, NEW YORK.

InsuLA'rnD TERMINAL non nnncritrcan APPARATUS.

. Application filed July 29, 1929, Serial No. 399,944, and in Great Britain January 3, 1920.

rial, such as a grounded metal casing, the.

casing being formed to receive the bush-1 ing. With such a recessed bushing or in-V sulator, it is well known that electrical dis- `charges of afbrush or corona nature take place very easily from the edge of any conductor carried therein, resulting in decreased safety and leadin to danger or' breakdown. 'lhe object of t is inventionv is to provide l an improved construction of insulated terminal device which will prevent such discharges taking place, and to that end it consists in providing a combined metal sheath and bushing, the sheath being connected to a termnial within the bushing and placed so as to surround the terminal and project beyond it.

rlhe annular space contained between the terminal and the surrounding sheath is filled with insulating material so that the edges of the sheath are entirely embedded therein. As is well known, the vprovision of such a sheath arrangedias described will relieve the inner termnial ,of the electrical stress which l wouldotherwise produce the discharge referred to, and will transfer such stress to the edge otthe sheath. As the edge ot this sheath is entirely' embedded in insulating material Vto the exclusion of all air, nobrush or corona discharge can ltake place, and consequently no ionozation of the air in the neighborhood ofthe terminal can occur.

The invention will bemore clearly understood by reference to the accompanying drawing, the single figure of which shows a cross-sectional view of my insulated termirial device. f

With reference to the drawing, l is an 1 insulator bodymounted in a vgrounded metal casing 2,# which may be, for instance, a portion of a transformer casing.l Y i The' insulator comprises a body provided l with a. central bore 3, one end of which is expanded to form an enlargement or chamber 4. In the end of the insulator body opposite the enlarged portion of the bore, and concentric with the smaller portion thereof is a cavity 5 in which is located av metal sheath 6 electrically connected as by conductive strips 7 vwith a conductor terminal 8 located in the smaller end of the bore 43.

The metal sheath 6 preferably projects a little beyond the lower end of the terminal member 8, and is embedded in insulating material as illustrated, the space 5, in the rear of the insulator, being filled with an 55 insulating compound, as shown.

ln installing my device, a conductor or cable from the transformer or other electrical apparatus within the main casing is secured by soldering or otherwise to the termi- 7G nal 8 which may be detached from the remainder of the device while this is being done. 'lhe terminal 8 is then brought into place within the bushing or insulator l and the strips 7 bolted thereto, the strips Z serv- 75 ing to maintain the terminal in position as well as to .connect it electrically with the sheath 6. The space 5 is then `filled with enough Vinsulating compound to cover the sheath 6, stripsy7 and the bolts and u per Bo end of the terminal 8, this compoun effectively preventing corona over theA surfaces of the conductive parts covered thereby. i

In the embodiment illustrated, the insulator is in one piece and shaped especially 85 to allow for the required construction of the terminal and sheath, but it will be understood that the insulator may be built up from more than one part to facilitate manufacture and assembly, and the arrangement .90 may be modified in other ways without departing from the spirit of my invention, the scope ot which is set forth in the appended claim.

`What 'I claim as new and desire to secure 054 by Letters Patent of the United States, is

An insulated terminal device com rising an insulator body having a central ore, va n metal casing surrounding said insulator body, a terminal mounted in one end of said' 100 bore, a conductor connected to the outer end of said terminal, said insulator body having a cavity concentric with said bore'and into said cavity and extending beyond the open at the end of said insulator 'body outer end of said terminal to seal the s ace y in .which the terminal is mounted, a metal between said conductor and the surounding l sheath located in said cavity and electrically metal casing. connected to said terminal, said metal sheath In witness whereof, I have" hereunto set Vsurrounding the inner end of said terminal my hand this twelfth da of Jul 1920.

and insulating material sealing said sheath l HENR TRE CHAM.

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