GB623002A - Improvements in dynamo-electric systems - Google Patents

Abstract

623,002. Smoothing direct currents; systems depending on two or more machines. BRITISH THOMSON-HOUSTON CO., Ltd., and PETCH, T. H. Oct. 17, 1945, No. 27134. [Classes 38 (ii) and 38 (iv)] [Also in Group XXXVII] Dynamo-electric machines are operated so as to afford in a variable voltage direct-current circuit the equivalent of a high-capacity condenser having no leakage. The armatures 11 and 12 of two direct-current motors, having suitable inertia, are mechanically coupled and are connected to a variable-voltage supply, the motor field windings 13 and 14 being separately excited from a constant source. Various constants of the motors and their associated circuits 'are so chosen that if the variable applied voltage attains a steady value for a period of time sufficient for the speed of the combination to reach a correspondingly steady value, the back-electromotive force of one of the machines, which acts as the condenser, becomes equal to that value of the applied voltage, the other machine serving to supply the mechanical losses of the first. Each armature may have resistances 17 and 18 connected in series therewith. A fly-wheel may be coupled to the armatures. The Specification contains a mathematical demonstration showing how the arrangement can be made equivalent to a circuit wherein a condenser having no leakage is connected across a variable voltage supply in series with the resistor 18. The applications to systems for timing the rate of closing of a contactor, and for affording a gradual rate of change of the exciting-current of a generator, are respectively illustrated in Figs. 5 and 8 (not shown).