Patent GB-165985-A (GB)
Title: A method of and apparatus for utilising an electric current to produce a modified curent or a correspondingly modified magnetic flux
IPC: H04B1/04
Filed: 1920-04-22
Abstract: 165,985. Igranic Electric Co., Ltd., (Cutler-Hammer Manufacturing Co.). April 22, 1920. Vapour and vacuum or low-pressure apparatus, arrangements of; frequency, changing. - In electronic apparatus for producing alternating current of a given frequency from direct current or from alternating current of different frequency, independent means are provided for positively subjecting the grids of the apparatus to an alternating potential. In the arrangement shown in Fig. 1, for converting direct current supplied by the lines L, L<1> into alternating-current of given frequency for driving a motor M, two electronic devices 2, 3 are employed, the anodes 9 of which are connected to the line L<1> and the cathodes 7 to the line L through the primary windings 4, 5 of a transformer T. A generator G producing current of the desired frequency is provided with two pairs of slip-rings 16, 17, the rings of each pair being connected to the grids 10 and cathodes 7 of one of the electronic devices 2, 3. The connections are such that the generator voltage is impressed alternately upon the two grids, thereby causing intermittent pulsatory currents to flow through the windings 4, 5 with a displacement of 180‹. The windings 4, 5 are connected to the cathodes in opposite, directions so that an alternating current of a frequency determined by the speed of the generator G is induced in the secondary winding 6 of the transformer T. In a modified arrangement, Fig. 2, a single electronic device 22 is provided, and the generator G has a single pair of slip rings connected to the primary winding 34 of a transformer t, with two secondary windings 35, 36, connected in opposite directions to the cathode 24 and to the grids 28, 29. The anodes 26, 27 are connected to the direct-current lines L, L<1> through the primary windings 4, 5 of transformer T' as shown. Batteries 23 are preferably included in the grid circuits. The electron discharge passes alternately to the anodes 26, 27, causing intermittent currents to flow in opposite directions through the windings 4, 5, to produce an alternating current of the desired frequency in the winding 6. An arrangement for converting three-phase current of any frequency to single-phase current of a given frequency is shown in Fig. 3. The electronic device 41 is provided with a single cathode 51 heated by a battery 60 which also energizes the. generator G through an adjustable resistance r. The current is supplied to the device 41 from the lines L<2>, L<3>, L<4> through a transformer T<1> comprising deltaconnected primary windings 42, 43, 44 and two sets of star-connected six-phase secondary windings 45 - - 50. The device 41 is provided with two sets of six anodee 52 - - 57, each anode being connected to one of the secondary windings of the transformer T<1>. The cathode 51 is connected to the star points of the secondary windings through windings 4, 5, the connections being such that the rectified currents produced in the device 41 traverse these windings in opposite directions. The generator G has two sets of slip rings 65, 66 arranged to produce potentials displaced by 180‹, the rings of each set being insulated through half their circumference. The rings are connected to the grids 58, 59 as shown, preferably through batteries 71. Intermittent pulsatory currents are thus produced in the windings 4, 5, which may be employed as the stator windings of a motor M<1>, or may be used to produce alternating current of desired frequency in a secondary winding 6. Specification 165,986 is referred to. Reference has been directed by the Comptroller to Specification 144,720.