US1946324A - High tension switch - Google Patents

Description

Feb. 6, 1934. KUNTKE 1,946,324

HIGH TENSION SWITCH Filed Dec. 51, 1931 Patented Feb. 6, 1934 UNITED STATES 1.94am. men TENSION swrrcn Alfred Kuntke, Eindhoven, Netherlands, assignor to C. H. F. Muller Aktiengesellschaft, Hamburg,-

Germany Application December 31, 1931, Serial No. 584,225,

and in Germany January 19, 1931 9 Claims. (Cl. 200-111) Switches for high voltages of the type as used in X-ray installations must have a considerable distance between their contact members when being opened so as to avoid a sparking-over. When closing such a switch the movable part must consequently cover a long path so that the switch must have a large size. However, this entails the drawback that the switching on operation requires more time than if the said path were 1 shorter.

The present invention relates to an improved switch having a small size and which provides for a short switching time.

It is known that metal parts between which a 6 high tension is set up may be disposed closer to each other by increasing the radius of curvature of the opposing surfaces of such parts. Therefore in high tension technics often conductors are used having a slight curvature. For this rea- 80 son, for instance, metal globes are used as contact pieces which contact with each other on switching on-the current. However, said globes have the drawback that due to their comparative- 1y large size they are not adapted to be very rapidly operated, whereas, as stated, an extremely quick operation of such relay switches is desired.

The high tension switch according to the present invention is so constructed that the switching path is formed between two opposing conductive bodies, whose surfaces have a radius of curvature which is large enough to prevent a sparking-over, and which bodies are not displaced with respect to each other. For switching on a separate part is used having a small 5 inertia with respect to the stationary conductive bodies adapted for establishing a discharge and which through an aperture provided in one of the surfaces is moved towards the surface of the other conductive body, thus establishing a discharge between.the movable part and the opposed stationary body.

This movable contact member forms part, for instance, of a relay or is connected, to the armature thereof, which in its turn is partly or entire-' 1y surrounded by the corresponding conductive surface.

In order to be able to switch on very quickly the device is arranged in such manner that the movable switching. member is electromagnetically retained behind the aperture of the corresponding conductive surface, whereas it snaps out by gravity as soon as the exciting current of the relay is interrupted.

The switches referred to above may be used with advantage in X-ray installations for closing the current of an X-ray tube at any desired moment. Especially when it desired to switch on withas little inertia as possible, the switches according to the invention are very advantageous, for instance, in apparatus for instantaneous pho- .0 tography in which the energy of a charged condenser is used for making an X-ray exposure and in which it is desired to send a current through the tube at any desired moment after charging the condenser.

The invention will be more clearly understood by reference to the accompanying drawing, representing, by way of example, a form of construction thereof used in an X-ray installation.

In this drawing 1 denotes an X-ray tube whose anode 2 is connected to one plate of a condenser 3 through a selfinduction 4. With the aid of means not represented this condenser may be charged up to a tension which permits a sufilcient current to be sent through the tube for a 76 short time. The selfinduction 4 has for its purpose to influence the course of the current strength as favourably as possible. The incandescent cathode 5 of the X-ray tube is connected to a metal globe 6. A second metal globe 7 rep- 80 resented in section is connected to the other plate of the condenser through the intermediary of a grounded conductor 8. The globes 6 and 7 form part of a switch with the aid of which the discharge current of the condenser may be switched on. They have metal surfaces by which the production of a breakdown discharge is avoided due to their slight curvature. Within the globe '7 is located a relay coil 9 secured, for instance, to the end of a metal tube 10 extending within the globe, said tube carrying the globe and forming part of the conductor 8. The coil 9 is connected between the metal tube 10 and a supply wire 11 which is led through the said tube so as to be insulated therefrom. The supply conductors 10 and 11 are connected to the two terminals of a current source 12 and between the conductor 11 and the source 12 is inserted a switch 13. Within the electro-magnet is arranged an armature ending at the bottom side in a pin 14. Due to the magnetic force this pin is retained in the position represented on the drawing in fulllines. The end of this pin lies behind an aperture 15 of the wall of the globe '7. If the switch 13 is opened the relay is deenergized and the armature drops so that the end of the pin 14 approaches the globe 6 through the aperture 15. Thus a discharge mayoccur between the globe 6 and the pin 15 which was impossible hitherto on account of the slight curvature of the surfaces of the lie globes 6 and 7. If desired, the distance of travel of the armature may be such that the pin 14 in its lowered position directly contacts with the globe 6, as indicated in dotted lines in the drawing, thus establishing a direct metallic connection between the incandescent cathode 5, the tube and the condenser. In many cases, however, this will not be required. since a suflicient quantity of energy is supplied by a spark discharge. In this case the path to be covered by the pin 14 is reduced to a minimum value.

Of course, the arrangement may also be such that the position of the switching member 15 which it assumes under the influence of gravity switching on is effected by means of an electromagnet. Furthermore it is also possible to use a spring instead of gravity.

If it is desired to use the switch also for switching 03 energies, one of the globes may be movably arranged, the interruption being effected by increasing the distance between the globes, whereupon the distance is reduced again to such an extent as it is adequate in accordance with the tension to be applied.

It is not absolutely necessary that the metal surfaces which due to their form prevent sparking-over be shaped as globes, since they may be also paraboloids or have other similar shape. Furthermore both surfaces or one of them may be constituted by a flat plate whose edge is bent or thickened so as to form a rounded portion.

What I claim is:

1. A switching device for electric currents un der high tension comprising two conductive members spaced apart to form a gap and having smooth adjacent surfaces of such character as to minimize concentration of the electrostatic field therebetween, one of said members having an aperture opposing the second member, a rodshaped switching member electrically connected to the apertured member and disposed behind the saidaperture and means to cause the switching member to project through the aperture in the direction of the opposite member.

2. A switching device for electric currents under high tension comprising two conductive globes spaced apart a distance which isv smaller than the breakdown distance of sharply bent surfaces and larger than the breakdown distance of the globes proper, one of the globes having at its ber and aligned with said aperture, means for holding said rod-shaped member in a position in which it is electrostatically shielded from the opposite member by the hollow member, and means comprising an electromagnet for causing the rodshaped member to protrude through said aperture toward the opposite member.

4. A high-tension switch comprising two conductive members spaced apart to form a gap which cannot be broken down by the high voltage tobe employed therewith, one of said members being hollow and having an aperture facing the, opposite member, a rod-shaped switching member enclosed by said hollow member and being held by gravity in a position in which it is electrostatically shielded from the opposite member by the enclosing member, and means comprising an electromagnet for forcing said rodshaped member against gravity and moving it into the electric field between the conductive members.

5. A high-tension switch comprising two conductive members spaced apart to form a gap longer than that which can be broken down by the voltage to be employed therewith, one of said members being hollow and having a perforation facing the opposite member, a movable rodshaped switching member enclosed in said hollow member and a spring biasing said switching member in a position in which it is electrostatically shielded by said hollow member from the opposite member, manually controllable means for moving said rod-shaped member to a position in which it protrudes through the aperture into the electric field between the conductive members.

6. A high-tension switch comprising two conductive members secured to high-tension conductors and spaced apart in vertical alignment to form a gap, the adjacent surfaces of said members being slightly curved, the distance of said members being smaller than the corresponding breakdown distance between sharp edges, the upper member being hollow and enclosing a vertically disposed rod-shaped switching member electrically connected with the enclosing member, the wall of the latter having at its lowermost portion an aperture through which the rod-shaped member may pass, and means operable at the will of the operator to prevent the rod from falling down through the aperture or render it free to fall down and cause the passage of the current between the members.

7. A high-tension switch comprising two stationary conductive members having each secured to it a high-tension conductor and a circuit controlled by said switch comprising said conductors, said members being mounted one above the other and spaced apart to form a gap, the adjacent surfaces being without sharp edges and protuberances to form a smooth corona-less surface, the distance of the members being smaller than the breakdown distance of the corresponding pointto-point discharge gap, the upper member being hollow and having at the bottom an aperture, a rod-shaped switching member disposed in the upper stationary member and vertically aligned with said aperture, a magnet coil and an auxiliary current source energizing said coil to prevent said switching member from dropping through the aperture by gravity and thereby causing the hightension circuit to be closed as long as the auxiliary current flows.

8. In a high-tension electric circuit a source of high-tension, a gap between two stationary conductive members, which cannot be broken down by said high tension, the adjacent surfaces of the members being. substantially spherical, one of the spherical surfaces being perforated and concealing from the non-perforated member a metal rod electrically connected to the perforated member, means for actuating the metal 'rod to project it through the aperture and to so condition the gap that it is bridged under the influence of said high tension.

9. Switching means for use in an X-ray system wherein the X-ray tube is operated by condenser for the e o! the switching member, and means for controlling the movement of the switching member to cause its passage through the aperture and to thereby discharge the condenser through the X-ray tube at a. desired instant.

ALFRED KUNTKE.

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