GB550036A - Improvements in and connected with direct current electrical supply systems comprising motor driven boosting generators - Google Patents

Abstract

550,036. Electricity supply systems. STONE, & CO., Ltd., J. Aug. 29, 1941, No. 11037. Convention date, May 13. [Class 38 (iv)] Variable-speed generators, with boosting by dynamo-electric machines.-A motor 20, connected across a variable voltage switch 11, 11a and arranged to run at constant speed, drives a boosting generator 24 in series with the source, and the field of the booster is caused to vary inversely with source variations whereby a constant voltage output 14, 28 is produced. Fluorescent lamps may thus be run at 60 or 80 volts from a variable-speed generator and battery system 2, 12 giving voltages varying between 28 and 45 volts. Rapid starting is provided by a series winding 19 on the motor which is subsequently counteracted by load current in a winding 51. The main motor field is composed of windings 17 in series with non-linear resistances 42a - d wherein increase of voltage causes a fall in resistance so that the motor field increases with applied volts and the speed remains constant. The booster has a series field 23, a constant current field winding 25 energized by the output voltage through a stabilizing ballast lamp 36, and a field winding 27 opposing the others and comprising a non-linear resistance as aforesaid whereby the boost volts fall as the source volts rise ; the field 27 may be in series with the motor field 17 and may be in a separate circuit with its own non-linear resistance. The resistances 42a - d are secured in positions on the booster such that their negative temperature coefficient compensates for temperature changes.