GB527192A - Improvements in self-starting synchronous motors - Google Patents

Abstract

527,192. Windings for dynamo electric machines. BARRACLOUGH, E., and MOSSAY, P. A. H. April 3, 1939, No. 10379. Addition to 481,504. [Class 35] In a self-starting synchronous motor with a double layer secondary winding having three phases E1, E2, D; El, E2 being the exciting windings and D serving as a damping winding, the relative arrangement of the groups of coils belonging to the respective phases on or about the periphery entails the sequence El, E2, DE2, E1, D - E1, E2, D and so on in the upper layer and E2, E1, D - E, E2, D - E2, E1, D &c. in the lower layer, D being the damping winding and E1, E2 the exciting windings of the secondary member of a motor. In the form shown, the upper row of references denotes the upper layer and the lower row the lower layer the sequences being as specified above. The winding shown is for a 2-pole machine having coils of full pitch of 180 electrical degrees and adapted for 3-phase star connection, the exciting winding being so connected that the effect is that of a coil pitch of <SP>2</SP>/ 3 full pitch, i.e., 120 electrical degrees, but the zones occupied by the conductors in each group need not be equal. Thus, that of the damping phase may be less or more than and that of each of the exciting windings more or less than 60 electrical degrees. Such a machine can be connected to a standard 3-phase slipring inductor motor starter so that part of the secondary binding gives the maximum excitation and part gives the maximum damping in synchronous running and assists synchronization at starting.