GB294563A - Improvements in or relating to asynchronous motors - Google Patents

Abstract

294,563. Naamlooze Vennootschap Hengelosche Electrische en Mechanische Apparatenfabriek, and Klinkhamer, H. A. W., (Assignees of Budie, E.). July 26, 1927, [Convention date]. Alternating-current induction machines. - To reduce the starting current of a three phase squirrel cage induction motor, each phase of the primary winding consists of two or more parts pertaining to the same poles and comprising different numbers of turns which at the successive starting steps are symmetrically connected so that a stepwise reduction in the effective number of turns is obtained. In the running position all the winding portions preferably are active. The parts which comprise a phase winding may be permanently connected together or they may be separate. Fig. 1 shows a series of connections in which the star-point is moved from d to c and from c to b while the final step gives a delta connection. It is not necessary to place the winding portions in the same slots; for example in the case of a machine having three slots per pole and phase and having twenty conductors in series, two slots may contain seven conductors each and the third six. If each phase is divided into two parts in the ratio of 4 : 1, the greater part may comprise the seven conductors in each of the two first slots and two conductors of the third slot, and the remaining four conductors in the third slot belong to the smaller winding portion. The Specification describes a number of other examples of changes of connection. The invention is applicable in connection with remote control and the regulation may be made automatic. In the Specification as open to inspection under Sect. 91 (3) (a), unsymmetrical starting connection are described. This subject-matter does not appear in the Specification as accepted.