US3639892A

US3639892A - High-voltage connector

Info

Publication number: US3639892A
Application number: US38161A
Authority: US
Inventors: William E Dill; Maurice G La Vault; Stanley L Kokoszka; William W Shrader
Original assignee: Raytheon Co
Current assignee: Raytheon Co
Priority date: 1970-05-18
Filing date: 1970-05-18
Publication date: 1972-02-01
Anticipated expiration: 1989-02-01

Abstract

A high-voltage power connector, and method of manufacture thereof, for use with plug-in modules, each section of the contemplated connector consisting of at least one central conductor and a shielding member coaxially disposed about the at least one central conductor and held in position by a dielectric disc which is so shaped as to eliminated areas of excessive electrical stress, the free ends of each conductor and shielding member being movable orthogonally to the dielectric disc so that when the modules are in their operating positions a shielded power connection is formed.

Description

Unite States r en Dill et al. 5] Feb. 1, 1972 [54] HIGH-VOLTAGE CONNECTOR 2,368,889 2/1945 Setterblade ..339/2Il X 72 Inventors: William E. mu, Natick; Maurice G. La 32:3 :22 11322 gf fi' 4 2 3;

vault Ashland; Stanley L Kokoszka 1C 0 as Framingham; William W. Shrader, West I Newton, a of Mass Zrn utvy Ecamu erlsi4arvm A. lihsainplijon ssls ant xammer awrence aa Assignee: Raytheon Company, Lexington, Mass- Attorney-Philip J. McFarland and Joseph D. Pannone [22] Filed: May 18, 1970 [57] ABSTRACT [21] Appl. No.: 38,161

A high-voltage power connector, and method of manufacture thereof, for use with plug-in modules, each section of the con- [52] "339/ 339/177 R templated connector consisting of at least one central conduceld 0 Search :1" 3 7 7 tor and a shielding member coaxially disposed about the at 3 l least one central conductor and held in position by a dielectric 339/ 7 l 6 14 143 278 C disc which is so shaped as to eliminated areas of excessive R f n Cm! electrical stress, the free ends of each conductor and shielding e ere mg l member being movable orthogonally to the dielectric disc so UNITED STATES PATENTS that when the modules are in their operating positions a 431 412 7/890 S d 339/177 R shielded power connection is formed. tu te 2,778,995 1/1957 Gross et al. ..324/64 4 Claims, 2 Drawing Figures HIGH-VOLTAGE CONNECTOR The invention herein described was made in the course of or under a contract or subcontract thereunder, with the Department of Defense.

BACKGROUND OF THE INVENTION This invention pertains generally to the art of making electrical connections between modules in an electrical system and particularly to making high-voltage connections between such modules.

It is known in the art that high voltage interconnections between separate modules may be made using conventional high-voltage connector techniques, i.e., when there is sufficient spacing between modules, conventional threaded male and female connectors may be used. In certain applications, however, where the spacing is limited, the size of the required connectors militates against their use, especially if it is desired that the modules be of the well-known plug-in" type. That is, plug-in modules of known construction may normally be used only in low power applications.

When high-voltage power connections are made in the vicinity of radiofrequency equipment it is of the utmost importance that there be no radiofrequency interference with such radiofrequency equipment due to such connections. This means that a continuous radiofrequency shield must be provided to isolate the high-voltage power connections from the radiofrequency equipment.

It is also necessary that every plug-in connection be so designed and operated that it remain free of corona. Although high-power connectors of known design are satisfactory with respect to freedom from radiofrequency interference and corona, such connections are, without exception, not easily made or broken. It follows, then, that such connectors are not adapted to use with plug-in modules.

Therefore, it is a primary object of this invention to provide a high-power connector for use with plug-in modules.

Another object of this invention is to provide a high-voltage connector which does not require threaded male and female portions.

Still another object of this invention is to provide a highvoltage power connector for use with plug-in modules which does not allow radiofrequency interference with associated radiofrequency equipment.

A further object of this invention is to provide a high-voltage power connector which is free of corona during operation.

A still further object of this invention is to provide an improved method for designing and fabricating a high-voltage power connector.

SUMMARY OF THE INVENTION These and other objects of this invention are attained by providing a pair of matching connectors, one for each module to be connected, each one of such connectors including a center conductor and an electrical shielding member coaxially disposed with respect to one another, the spacing therebetween being maintained by an interpositioned dielectric disc having a cross-sectional shape such that the maximum electrical strength at any point thereon does not exceed the threshold for corona discharge. The end of each center conductor and each electrical shielding member is so formed and mounted that, when the modules to be connected are in place, the free ends of the two center conductors and the two electrical shielding members make contact, respectively, with one another.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of this invention reference is now made to the following description of a FIG. 2 is a crosssectional view of a matching pair of connectors, according to this invention, the two illustrated connectors being shown in position relative to one another just before seating.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1,

modules

5,6 7 supporting, respectively,

connectors

10, 12 are shown to illustrate the flexibility with which modules using power connectors according to this invention may be mounted. Thus, letting module 5 be a highvoltage power supply for a radar, module 6 be the modulator and module 7 be the radiofrequency power oscillator, it may be seen'that disconnection of any one of the three modules from either, or both, of the other modules may be accomplished by moving the module to be disconnected in a direction as indicated by arrows a, b, c, d. Obviously, the

modules

5, 6, 7 would each be mounted in guides (not shown) to permit motion in a desired direction. It will be observed, for reasons explained hereinafter, that upon disconnection the free end of the connector 10 simply moves out a short distance from the wall (not numbered) of the module to which it is af-- fixed,'thus permitting the module to be removed without interfering with adjacent modules.

Referring now to FIG. 2 it should be noted that the matching connectors shown are in position just prior to their seating one against the other. That is, the modules on which the

connectors

10, 12 are mounted are just short of being juxtaposed. Therefore, the spring-loaded members of the

connectors

10, 12 are in their disconnected positions. Connector 10 includes a ring 13 formed from the parent-conductive material of the module wall. The ring 13 is formed so as to support a mushroom configured ring contactor l5. Springs 17 and retaining bolts 19 coact between the ring 13 and contactor 15 as shown to force the contactor 15 to the left before the module is seated in its desired final position. Electrical contact is made between ring 13 and contactor 15 with leaf springs 16. The ring 13 also supports a dielectric disc in any desired manner. As shown here, it has been chosen to provide clamping element shown generally at 23 which is bolted to the ring 13. It is noted here in passing that the clamping element 23 preferably is formed integrally with the dielectric disc 21 so as to create a liquid seal as well as a support for such disc. A circular opening (not numbered) is formed centrally of the dielectric disc 21. Such disc is undercut as indicated and an electrically conductive coating 27 is applied as shown. It is preferred that the dielectric disc 21 be fabricated from high strength porcelain although other materials such as polycarbonate, sometimes known by the trademark of General Electric Corporation, LEXAN, glass filled diallyn phthalate or aluminajmay be used. The leakage path across the dielectric disc may, as shown on the left-hand side of the dielectric disc 21, be lengthened by forming concentric rings. A bushing 29 is mounted in the opening in the dielectric disc 21. One end of the bushing 29 may be shaped in any desired manner to permit connection of the bushing 29 with the center connector 31 of a powercable. For example, here the right-hand side of the bushing 29 is beveled so that the complementary end of the center conductor 31 may be bolted to it as indicated. An electrical contactor 33, which generally has the shape of a mushroom, is slidably mounted as shown in the bushing 29, there being a helical spring 35 and a number of leaf springs 37 disposed between the stern of such electrical contactor and the bushing 29 to force the electrical contactor 33 to the left in the Figure when the module is not seated and to permit current flow from the center conductor 31 to the contactor 33 without passing through the helical spring 35. A stop 39, which may be threaded on the bushing 29 as indicated, holds the electrical contactor 33 within the bushing 29 and serves as an oil seal.

The connector 12 is, except as will be now noted, identical with connector 10. Thus, the ring 13' supports a number of leaf springs 41 in place of the contactor 15. Each one of the leafsprings 41 may be affixed to the ring 13' in any convenient manner as, for example, by a retaining ring 43 which is screwed onto the ring 13' in the manner illustrated. Each one of the leaf springs 41 is so dimensioned and positioned that it may be deformed by the conductor 15 when the modules are juxtaposed. The electrical contactor 33 which is mounted on the bushing 29' as shown is fabricated from any desired electrical contact making material and may as here shown be a simple spring-loaded button contact.

When the modules are juxtaposed the contactor 15 presses against individual ones of the leaf springs 41 and the electrical contactor 33 presses against the electrical contactor 33, thus making connection between the power cable in each module.

It should be noted here that the mating of the two connectors may be accomplished by moving the two modules toward each other along a line parallel to the axis of symmetry of

connectors

10, 12 or by moving the modules relative to each other along a line perpendicular to such axis. In this latter mode of movement an automatic safety feature is inherent when the electrical contactor 33 presses against the leaf springs 41 to discharge lethal voltages.

While any one ofa variety of known design approaches may be taken to determine the shape of the dielectric disc 13 for any particular application, it is preferred that the extrapolated Liebmann method as outlined in Analysis and Computation of Electric and Magnetic Field Problems, pg. 270, by K. J. Binns and P. J. Lawrenson, published by MacMillan Company, New York 1963, be followed. According to the Liebmann method, the design problem may be solved by specifying the boundaries of the various materials in the region of interest, the dielectric constants of each and the voltages at the boundaries of the region of interest. Such information is then used to program a computer to lay out a resistance analog matrix of resistors wherein the value of each resistor is inversely proportional to both the dielectric constant of each material and the distance from the axis of symmetry of the connector. A typical matrix size is 48 80, but larger or smaller matrices may be used, depending upon the accuracy required of the computation. The voltage at each point of the matrix is then determined in terms of the voltage at the adjacent four points. When an iterative procedure is followed it will be found that, after a number of calculations subsequent calculations change by a very small amount. The final voltage matrix may then be used to determine the equipotential lines across the dielectric disc. In a practical embodiment it should be noted that the equipotential lines across the dielectric disc should be as equally spaced as possible to avoid areas where the electric stress on the material of the dielectric disc may be in excess of the potential at which a corona discharge may occur. After the equipotential lines are computed, the geometry of the dielectric disc, center conductor(s), and shield may be altered, and the calculation repeated.

Having described a preferred embodiment ofthis invention, it is evident that other embodiments incorporating its concepts may be used. For example, the shape of the central conductors may be changed if, for example, it is desired to pass more than one powerline through the connectors. Further, the shape of dielectric discs may be changed ifa dielectric liquid is not used within either or both modules.

It is felt, therefore, that this invention should not be restricted to its disclosed embodiments but rather should be limited only by the spirit and scope ofthe appended claims.

What is claimed is:

1. High-voltage electrical power connectors for plug-in means for maintaining the maximum gradient of the electrostatic field between the central conductor and the shielding element at a value less than the value causing a corona discharge;

b. means for affixing the shielding element of each one of the mating coaxial lines to a separate one of the plug-in modules to be connected;

or spring-loaded contact means mounted on the free end of one of the conductors and one of the shielding elements for completing a shielded electric circuit between the pair of mating coaxial lines when the plug-in modules are juxtaposed and,

d. the dielectric spacer in one of the mating coaxial lines being spaced from the corresponding dielectric spacer of the other one of the mating coaxial lines when the plug-in modules are fully engaged.

2. High-voltage electrical power connectors as in claim 1, wherein the dielectric spacer is undercut adjacent to the central conductor, the area undercut being covered with an electrically conductive glaze.

3. High-voltage electrical power connectors for plug-in modules as in claim 1 wherein one surface of each one of the dielectric spacers is convoluted and the second surface of each one thereof is substantially planar for adapting such connectors to use when a dielectric liquid covers the surfaces of the connectors within such modules.

4. High-voltage electrical power connectors for plug-in modules comprising:

a. a pair of mating coaxial lines, each one thereof including:

i. a central conductor; and ii. a shielding element, such shielding element being concentric with the central conductor;

iii. a dielectric spacer, such dielectric spacer being disposed between the central conductor and the shielding element, for maintaining the coaxial relationship between the central conductor and the shielding element, the cross-sectional shape of such dielectric spacer varying to maintain the maximum gradient of electrostatic field between the central conductor and the shielding element at a value less than the value causing a corona discharge; and

iv. a chamber, such chamber being partially bounded by the shielding element and the dielectric spacer;

b. means for affixing the shielding element of each one of the mating coaxial lines to a separate one of the plug-in modules to be connected; and

c. spring-loaded contact means, mounted on the free end of one of the conductors and one of the shielding elements, for completing a shielded electric circuit between the pair of mating coaxial lines when the plug-in modules are juxtaposed, such spring-loaded contact means being mounted such that the volume of the chamber is invariant with the relative position of the plug-in modules.

Claims

1. High-voltage electrical power connectors for plug-in modules comprising: a. a pair of mating coaxial lines, each one thereof including: i. a central conductor; ii. a shielding element concentric with the central conductor; and iii. a dielectric spacer disposed between the central conductor and the shielding element for maintaining the coaxial relationship between the central conductor and the shielding element, such dielectric spacer including means for maintaining the maximum gradient of the electrostatic field between the central conductor and the shielding element at a value less than the value causing a corona discharge; b. means for affixing the shielding element of each one of the mating coaxial lines to a separate one of the plug-in modules to be connected; c. spring-loaded contact means mounted on the free end of one of the conductors and one of the shielding elements for completing a shielded electric circuit between the pair of mating coaxial lines when the plug-in modules are juxtaposed and, d. the dielectric spacer in one of the mating coaxial lines being spaced from the corresponding dielectric spacer of the other one of the mating coaxial lines when the plug-in modules are fully engaged.

4. High-voltage electrical power connectors for plug-in modules comprising: a. a pair of mating coaxial lines, each one thereof including: i. a central conductor; and ii. a shielding element, such shielding element being concentric with the central conductor; iii. a dielectric spacer, such dielectric spacer being disposed between the central conductor and the shielding element, for maintaining the coaxial relationship between the central conductor and the shielding element, the cross-sectional shape of such dielectric spacer varying to maintain the maximum gradient of electrostatic field between the central conductor and the shielding element at a value less than the value causing a corona discharge; and iv. a chamber, such chamber being partially bounded by the shielding element and the dielectric spacer; b. means for affixing the shielding element of each one of the mating coaxial lines to a separate one of the plug-in modules to be connected; and c. spring-loaded contact means, mounted on the free end of one of the conductors and one of the shielding elements, for completing a shielded electric circuiT between the pair of mating coaxial lines when the plug-in modules are juxtaposed, such spring-loaded contact means being mounted such that the volume of the chamber is invariant with the relative position of the plug-in modules.