GB670081A - Improvements relating to magnetic amplifiers - Google Patents

Abstract

670,081. Magnetic amplifiers. MONTGREMIER, P. A. DE, and GACHET, P. Sept. 17, 1948, No. 24479/48. [A Specification was laid open to inspection under Sect. 91 of the Acts, Sept. 13, 1949.] Class 40 (iv). [Also in Group XXXVII] In a magnetic amplifier, two back-to-back connected transductors Tl, T2 each comprise a main winding 6 and a reaction winding 12 which is energized by rectified current from a voltage tapping on the main winding associated with the other transductor. As shown, in each transductor, the main winding is connected in series with a bridge rectifier 8 to a common alternating current supply, while the reaction winding is energized from a variable tap 15 on the main winding of the other transductor through a condenser 16 and a rectifier 14. The transductors are normally balanced, but the application of direct current potential to seriesconnected control windings 9 causes the inductances of the two transductors to change in opposite senses according to the applied polarity. This unbalance is enhanced by a change in current in the reaction windings and by the establishment of a direct current in series-connected windings 18 due to the difference in the rectified main-winding currents passing through resistances 17. A variable resistance 20 is provided to control the intensity of the current in windings 18. Resistances 17 are parts of the output circuit of the amplifier and may be, for example, exciting windings of a motor so that the direction of rotation is controlled by the polarity of the control voltage. In a modification, Fig. 2 (not shown), the rectifiers 8 are transformer-coupled in series with the main windings and the resistance 20 is omitted, windings 18 being energized from various taps on the resistances 17.