GB159939A - Improvements relating to dynamo electric machines - Google Patents

Abstract

159,939. White, A. E., (U.S. Light & Heat Corporation). Nov. 11, 1919. Rotary transformers; exciting.-Continuouscurrent dynamo-electric machines for operation as rotary transformers or balancers, double-current and self-regulating generators, &c. are provided with a single fractional pitch or other winding on the armature and with two distinct sets of windings on the field magnet giving rise to fields which may be regulated independently to vary the voltages at different sets of commutator brushes. Figs. 1 and 2 illustrate a construction in which the poles 11, 12, 14, 15 are provided with coils 17 - - 20 connected in series across the mains 21, 22, and producing a field with which the brushes 7, 8 co-operate, the poles 11, 12 being of one polarity and the poles 14, 15 of the opposite polarity. The poles 13 - - 16 are fitted with coils 23 - - 26 also connected in series across the mains 21, 22 and tending to make the poles 13, 14 of one polarity and the poles 15, 16 of the opposite polarity; brushes 9, 10 co-operate with this field. The two fields cross one another substantially in the form of the Greek letter #. The coils of the armature winding have a pitch of approximately 120‹. The machine may be operated as a rotary transformer by admitting primary current through one set of brushes, for example, the brushes 7, 8 and taking current from the brushes 9, 10, or it may be driven to act as a double-current generator, currents being taken from both sets of brushes; the voltages of the circuits may be adjusted either by hand or automatically by means of rheostats 27, 28 and a reversing-switch 29. The brush 10 may be dispensed with, the two external circuits being connected between the brushes 7, 9 and 8, 9 respectively. A three-brush machine may be used to step down the supply voltage for battery-charging and arc-lighting, Figs. 12 and 21, or as a balancer on a three-wire circuit, Fig. 20, or to develop a three-wire system from a two-wire supply. Figs. 22 and 23 illustrate a double-current generator with a battery connected to the brushes 10, 11 and a lighting or other load circuit connected on the one side to the brush 10 and on the other side to the brushes 12, 13 which are joined through windings 18, 19 arranged on the poles 6, 7 so as to magnetize these with the same polarity. The windings on the other poles tend to give the poles 2, 3 one and the same polarity and the poles 4, 5 the opposite polarity; the current from the brushes 10, 11 remains unchanged in direction when the direction of rotation is reversed. An automatic rocking-switch may be added to cause current to pass through both windings 18, 19.