GB234146A - Improvements in or relating to means for regulating direct current machines - Google Patents

Abstract

234,146. Rushen, P. C., (Siemens- Schuckertwerke-Ges.). Dec. 17, 1923. Exciting.-The speed of a continuous-current machine is maintained constant by exciting the, field with an electron current controlled by two factors, one depending on the speed of the machine.. and the other depending on an additional adjustable. voltage. A continuous-current motor 1, Fig. 2, has a shunt field winding 2 and a separate winding 3 acting in the same direction and fed from the mains through a thermionic valve. In the circuit of the valve grid 6 there are connected a tachometer dynamo 7 driven by the motor and an adjustable opposing battery 12. The voltage of the battery 12, and the rheostats are adjusted so that at the desired speed a mean current flows through the winding 3. An increase of motor speed results in an increased potential of the grid 6 and the motor slows down again owing to the greater current in the winding 3. The speed of the machine may be varied by a simultaneous adjustment of the rheostat 8 in the main field circuit and the voltage of the battery, and the speed is kept automatically at this value. In the arrangement shown in Fig. 5, the motor 1 has constant excitation due to the winding 2, and the speed is varied by altering the voltage EB applied to the brushes. The adjustable voltaga opposing the tachometer-dynamo voltage may be obtained by tapping off a portion of the applied voltage E<B>. In the case of a motor adapted for speed regulation on the Ward- Leonard principle, the opposing voltage may be tapped from the terminals of the generator field winding. A magnetron may take the place of the electron tube shown.