GB404739A - Improvements relating to direct current electric motor equipments operated in connection with rotary direct current transformers - Google Patents

Abstract

404,739. Control of D.C. motors. PESTARINI, G. M., 4, Tapton House Road, Sheffield. July 28, 1932, Nos. 21337/32 and 16479/33. [Class 38 (iii).] In a system in which a motor 7, Fig. 1, is supplied with constant current from a rotary transformer 2 provided with a variator winding 9 whereby the current may be adjusted, the motor field winding 8 and the variator winding 9 are supplied with a voltage which varies inversely as the secondary voltage of the rotary transformer. As shown in Fig. 1, the windings 8 and 9 are connected in series across brushes 4, 5, of the transformer. Alternatively, one of these windings may be connected across the brushes 4, 5, in series with the field of an exciter supplying the other winding, or the windings may be energized in series from an exciter having a field winding connected across the brushes 4, 5. The excitation of such an exciter may have a component of constant value. In Fig. 5 the windings 8, 9 are supplied from an exciter 11 having opposed field windings energized respectively by the supply, and an exciter 19 driven by the motor 7. In a modification the exciter 11 has two fields, one constant and the other energized by the primary current of the transformer 2. In a further modification, both windings of the exciter are energized from the supply and one is regulated by resistance under the control of a wattmeter relay measuring the power of the motor circuit.