GB420304A - Improvements in and relating to means for obtaining constant voltage from variable speed dynamos - Google Patents

Abstract

420,304. Automatic regulation; dynamoelectric machines. DYNAMIC DEVICES, Inc., 2973, Kingsley Road, Cleveland, Ohio, U.S.A. May 29, 1933, No. 15463. Convention date, June 3, 1932. [Classes 35 and 38 (iv)] The voltage of a variable-speed generator is rendered constant by the provision of a constantly energized auxiliary field winding opposing the main field winding and partially neutralizing it, thereby producing very rapid changes of flux on the operation of a vibratory contact in the main field circuit. This contact may be operated by the flux of the neutralizing winding as indicated in Fig. 1, where a resistance 47 in series with the main field windings 6 is intermittingly short circuited by a contact 25 subject to the flux of the neutralizing winding 7. As shown in Fig. 2 the contact 25 is operated by the flux of a ferrous core member 13 embracing the winding 7 and secured in a cut-away portion of the field yoke 1. The winding 7 occupies one pole of a four pole machine and the main windings 6 occupy the remaining poles. Preferably the winding 7 is weaker than a winding 6. In another arrangement, Fig. 4 one winding 7 has a part 71 in series with the contact 25, and the windings 6 discharge through this part, the resistance 47 being omitted. The flux of the winding 7 may operate a reverse current cut-out 161 as indicated in Fig. 5. An overload coil in series with the dynamo output may insert a resistance in series with the main field windings 6 on excess current demand. In an application of this method of voltage regulation to a third-brush current-regulated generator the main field winding circuit is connected in series with the third brush and the neutralizing winding across the main brushes. In a bipolar generator a neutralizing winding 182 is arranged on one of the field poles in addition to the main winding 6, and the vibrating contact 25 may be arranged as indicated in Fig. 8. The invention may be embodied in accessory apparatus, Fig. 10, consisting of a base 203 secured in a gap in the field yoke by a single screw 204. The base carries the vibrating switch and a neutralizing coil 196 adapted to encircle one field pole and to energize a magnetic member 213 operating the switch. In a modification the neutralizing winding 196 is coiled around a core energizing a co-operating spring-mounted armature carrying the switch contact.