GB108226A - Improvements in or relating to Apparatus for Producing Unidirectional Electric Currents of a Potential Sufficiently High to Operate X-ray Tubes. - Google Patents

Abstract

108,226. Rieber, F. Sept. 7, 1916. Commutator switching-arrangements.-In apparatus for producing unidirectional currents of high potential from a source 10, 11 of alternating current, for operating X-ray tubes &c., a transformer having its primary winding 12 connected to the source 10, 11 is provided with a number of low-potential secondary windings 13 which are connected through reversing-switches C in series to a unidirectional high-potential circuit D. The rotating parts of the reversing-switches are mounted on a shaft 14 driven by a synchronous motor at such a speed that two positive and two negative half-waves are impressed upon each switch with each revolution of the shaft 14. The stationary parts of each reversing-switch comprise four pairs of brushes 15, 15a; 16, 16<a>; 17, 17a; 18, 18<a> arranged round the shaft at intervals of ninety degrees. One set of brushes 15, 16, 17, 18 is arranged to make contact with a brass segment 19 of about one hundred and eighty degrees in extent and sunk in the insulating material of which the shaft is made; the other set of brushes 15a, 16<a>, 17a, 18<a> co-operates with a similar brass segment 20 mounted on the opposite side of the shaft. Each pair of brushes is connected by a conductor 21 and the terminals of each transformer secondary are connected with the brushes 15, 17 of the adjacent switch, the brushes 16, 18 being joined in series by wires 22, 23 leading to the circuit D. Each segment 19, 20 is held on the shaft by dovetails 26; the shaft is formed with ribs 27 forming insulating extensions of the segments. The transformer and switches are placed together in a casing filled with oil. The shaft 14 is hollow and open at one end to admit the oil, and, to prevent arcing, oil ducts 29 are provided in the shaft adjacent to the ends of the segments 19, 20, causing jets of oil to be thrown out as the shaft rotates. A continuous-current voltmeter E may be connected across one or more of the switches and a continuous current ammeter F may be connected in circuit; a safety connexion 30 to earth may be made from the junction of the meters, as shown,