Patent GB-191415871-A (GB)
Title: Improvements in Interrupting Devices for High Tension Electric Currents.
IPC: H05G1/70
Filed: 1914-07-02
Granted: 1915-08-05
Abstract: 15,871. Siemens Bros. & Co., [Siemens & Halske Akt.-Ges.]. July 2. R÷ntgen-ray and like apparatus.-Relates to a combination of low tension and high tension interrupters for use with a group of X-ray tubes or other devices energized by current impulses. The high tension interrupter consists of rows of stationary segmental conducting plates c, Fig. 3, and revolving bridge-pieces p mounted on arms b rigidly attached to a motor-driven shaft a. During the revolution, the bridge-pieces come into line simultaneously with the plates of a row, leaving small air-gaps across which discharge takes place. The first and last plates of the respective rows c1, c2, c3, Fig. 1, are joined up in parallel circuit with the respective X-ray tubes R1, R2, R3, and with the secondary t2 of the sparking transformer J. The motor M driving the shaft a also drives synchronously therewith the low-tension primary coil interrupter U which is of the revolving mercury-jet type. The stationary contacts e<1>, e<2>, e<3> are so disposed relatively to those of the high tension interrupter that the secondary circuit is closed when the primary is opened and not otherwise. The object is to pass 'direct' impulses through the tubes and to eliminate inverse' impulses. To prevent inverse' impulses from passing across the air-gaps, the bridge-pieces are arranged in staggered relation. Hand switches are inserted in the primary circuits of the tubes so that any tube can be disconnected. In a modified arrangement, the sparking transformer has two primaries oppositely wound and alternately energized by the mercury interrupter the stationary contacts of which are placed close together. In the case of an even number of tubes a discharge is transmitted by the secondary interrupter at every reversal. In the case of an odd number of tubes, double the number of stationary contacts may be used on the primary interrupter, each alternate one overlapping with the next. The reversal between the overlapping contacts is slow in consequence of temporary short-circuiting whereas the quick reversal between the alternate separated contacts produces effective secondary impulses. The breaks between the primary interrupter contacts may be bridged over by closing switches, for the purpose of throwing one or more of the tubes out of action. In another modified arrangement for working with an odd number of tubes and double the number of contacts in the primary interrupter, a resistance w, Fig. 7, is placed between one of two transformer windings and the alternate contacts e<2>, e<4>, e<6>. Each alternate breakage is stated to produce a strong secondary impulse. In a further modification for the same purpose, a resistance is interposed in the middle of each of the stationary contacts, and the points of connexion to the transformer windings are so disposed that the resistance is included in the circuit at alternate breakages. Modifications for use on three-phase circuits are also described. In one of these the arrangement is like that shown in Figs. 1 and 2 with the addition of a three-phase, star-wound, auto-transformer directly connected to the mains. One terminal of the primary of the spark transformer is connected to the neutral point of the star, and the other terminal to the mercury of the revolving jet. The stationary contacts traversed by the jet are connected through regulating resistances to the respective windings of the star transformer. One or more of the tubes in the secondary circuit can be put out of use by placing short-circuiting bars across the corresponding terminals of the high tension interrupter. In another arrangement, shown in Fig. 11, for three-phase working, the short interval between the stationary contacts e', e', e<3> of the mercury interrupter U is stated to produce a reversal of magnetism in the primary t<1> and thus an augmented impulse in the secondary t<2> of the transformer J. Each contact is divided into two parts bridged over by switches, one or more of which are opened when the tubes are put out of use.