US2450273A

US2450273A - High-voltage terminal

Info

Publication number: US2450273A
Application number: US662036A
Authority: US
Inventors: Dubilier William
Original assignee: Cornell Dubilier Electronics Inc
Current assignee: Cornell Dubilier Electronics Inc
Priority date: 1946-04-13
Filing date: 1946-04-13
Publication date: 1948-09-28
Anticipated expiration: 1965-09-28

Description

Patented Sept. 28, 1948 UNITED STATES PATENT OFFICE HIGI-LVOLTAGE TERMINAL Application April 13, 1945, Serial No. 662,036

4 Claims.

This application is a continuation-in-part of my copending application Serial No. 466,901, filed November 25, 1942, for Electrical capacitor, now Patent No. 2,398,417.

This invention relates to high voltage terminals for enclosed electrical apparatus and more particularly to such terminals for electrical apparatus, for example electrical condensers, for operation at very high frequencies as is the case with apparatus used in radio transmitters.

In electrical apparatus, such as condensers, enclosed in a casing with or without a filling of oil or other insulating fluid, the construction of satisfactory high voltage terminals for carrying heavy currents of the order of 50 amperes and upwards at high frequencies becomes difiicult as terminals and conductors of normal construction become hot with the result that the losses are seriously increased and may in some cases be come greater than those of the apparatus itself.

' This difiiculty can be overcome by dividing the current between two or more conductors, as has been proposed in the past, and the main object of the present invention is to provide an improved terminal ccnstruction for such a multiple conductor arrangement.

The invention as to its further objects and novel aspects will become more apparent from the following detailed description taken in reference to the accompanying drawings forming part of this specification, and wherein:

Figure 1 is a cross-section through a terminal structure constructed in accordance with the principles of the invention.

Figure 2 shows amodification of the terminal structure according to the invention.

Like reference characters identify like parts in both views of the drawings.

Referring more particularly to Figure 1, it has been assumed that the terminal shown constitutes the high voltage terminal of a condenser (not shown in the drawing) housed in a metal casing IE], only part of which is shown, the casing constituting the other terminal of the condenser. The casing 10, which may be either cylindrical or square, is closed by a cover ll preferably of insulating material, such as ground mica and a binder compressed into solid shape and known under the registered trade-mark "Mycalex or the like, fixed to a flange of the casing by means of bolts l2, a gasket l3 being provided to maintain the joint liquid-tight. The cover H has a central circular opening M, the edge l5 of which is of reduced thickess so as to provide on each side of the cover seatings for annular gaskets I6 and I1 consisting of cork or other seating material impervious to any liquid used for filling the casing, and having a channelshaped cross-section. Seated on the gaskets It and ll are the inner ends of a pair of insulating tubes l8 and 29 preferably consisting of heatrcsisting glass such as the material sold under the registered trade-mark Pyrex or the like. The outer ends of the tubes It and 20, respectively, fit into further gaskets 2| and 22 in annular depressions in a pair of

discs

23 and 24 of insulating material such, for example, as a phenolic condensation product known under the registered trade-mark Bakelite.

The

discs

23 and 24 are pressed against the tubes l8 and 2t) and the gaskets on the cover H by means of conducting rods 25 and 26, extending through the tubes and having their ends passing through the discs 23-and 2d. The lower ends of the rods 25 and iii are secured on both sides of the disc '24 by means of nuts 21, 28 and 3B, 3!, respectively, and then the whole terminal structure is clamped in a rigid and liquidtight manner by

nuts

32 and 33 on the upper ends of the rods and on the outer surface of the disc '23.

Suitable washers or gaskets 34 and 35 (or a single washer) of cork or the like are interposed between the nuts 21, 28 and the disc 2A to make the joint liquid-tight. Terminal strips or leads 3% and 31 from the condenser or other electrical device (not shown) in the casing are clamped below the nuts 21, 28 so as to be electrically connected to the conducting rods 25 and 2.6, which are preferably made of copper.

The projecting upper ends of the rods 25 and 26 may be joined by a common connecting element such as a metal washer 38 clamped between the

nuts

32, 33 and the disc 23, and additional terminal nuts 43, M may be provided for connections from the condenser to the other apparatus in an electrical system. While only two conducting rods 25 and 26 appear in the figure, actually the construction shown preferably has four, although any desired number from two upwards may be provided in order that there may be two or more separate paths for the current flow through the terminal.

This improved insulated terminal structure, besides enabling simple parts of relatively inexpensive materials to be used, has the further advantage that no continuous path exists through the dielectric between the high potential terminal and the casing. Consequently, the electric strain in the dielectric material is greatly reduced. This makes it possible to use a cheaper material or to increase substantially the operating voltage for which a. terminal of given size can be used.

Thus, electric flux will pass from the casing 18 through the cover H to the edge of the opening M and from there through intervening air space to the high potential conductors 25 and 26. Only a small amount of flux will pass through the considerably longer path offered by the tubes I8, 20,

discs

23, 24, and the intervening air gaps. Accordingly, therefore, the dielectric material of the cover II will be greatly relieved of electrical stress, so that the operating safety is substantially increased or a higher operating voltage can be used.

In addition to the improved dielectric properties referred to above, the division of the current between two or more parallel conductors prevents or reduces over-heating and thus avoids the disadvantages referred to above.

It will be appreciated that the above description is by way of example only and that structural details may be varied within the scope of the invention. Thus, instead of using open-ended tubes, these members may be formed with one end closed, that is, may be cup-shaped as shown at 44 and 45 in Figure 2, and assembled with their open ends abutting against the edge l of disc or cover I i the conductors passing through suitably formed holes in the closed ends. Furthermore, the conductors themselves may consist of wires or strips (instead of rods with screwthreaded ends) and may be secured in position after assembly and the application of sufficient tension to insure that the joints are liquid-tight, by welding or soldering the lugs thereon or in any other convenient manner.

While I have shown and described a desirable embodiment of the invention, it is understood that this disclosure is for the purpose of illustration and that various changes in shape, proportion and arrangement of parts, as well as the substitution of equivalent elements and materials for those herein shown and described, may be made without departing from the spirit and scope of the invention as defined in the appended claims. The specification and drawing are accordingly to be regarded in an illustrative rather than a limiting sense.

I claim:

1. A terminal structure for a high frequency, high voltage apparatus enclosed in a metallic casing having an insulating wall provided with an opening, comprising a pair of cup-shaped insulating members each having a bottom portion and a cylindrical portion separate therefrom and engaging a groove of said bottom portion, said members being arranged on each side of said wall with the open ends of said cylindrical portions abutting against the opposite edge zones of said wall around said opening, a plurality of conductors passing through said opening and said bottom portions, said conductors being spaced from each other and from the edge of said opening, and means for mechanically securing said conductors to said bottom portions to hold the complete assembly together.

2. A terminal structure for a high frequency, high voltage apparatus enclosed in a metallic casing having an insulating wall provided with an opening, comprising an insulating wall member provided with an opening a pair of cup-shaped insulating members having cylindrical and bottom portions and arranged on each side of said wall with the ends of said cylindrical portions abutting against opposite seatings of reduced thickness of saidv wall around said opening, a plurality of conductors passing through said opening and the bottom portions of said members, said conductors being spaced from each 'other and from the edge of said opening, and

means for securing said conductors to said bottom portions to hold the complete assembly together.

3. A terminal structure for a high frequency, high voltage apparatus enclosed in a metallic casing having an insulating wall provided with an opening, comprising an insulating wall member provided with an opening, a pair of cupshaped insulating members having cylindrical and bottom portions and arranged on each side of said wall with the inner ends of said cylindrical portions abutting against opposite seatings of reduced thickness of said wall around said opening, sealing gaskets interposed between said members and said seatings, a plurality of conductors passing through said opening and the bottom portions of said members, said conductors being spaced from each other and from the edge of said opening, and means for securing said conductors to said bottom portions to hold the complete assembly together.

4. A terminal structure for a high frequency, high voltage apparatus enclosed in a metallic casing having an insulating wall provided with an opening, comprising a pair of cup-shaped insulating members each having a bottom portion and a cylindrical portion separate therefrom and engaging a groove of said bottom portion, said members being arranged on each side of said wall with the open ends of the cylindrical portions abutting against the opposite edge zones of said wall around said opening, a plurality of conductors passing through said opening and the bottom portions of said members, said conductors being spaced from each other and from the edge of said opening, means for securing said conductors to said bottom portions to hold the complete assembly together, and sealing gaskets interposed between the cylindrical and bottom portions of said members and between said members and said wall.

WILLIAM DUBILIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 608,906 Poche Aug. 9, 1898 1,089,549 Halbleib Mar. 10, 1914 1,160,702 Faccioli Nov. 16, 1915 1,932,456 Gaston Oct. 31, 1933 FOREIGN PATENTS Number Country Date 7 233,880 Great Britain May 21, 1925 77,584 Sweden Feb. 17, 1932