GB366251A - Improvements in and relating to electric motor control - Google Patents

Abstract

366,251. Maintaining equal speeds. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Rogers; H. W. ; 10, Parkwood Boulevard, Schenectady, New York, U.S.A.) Jan. 13, 1931, No. 1165. Convention date, Jan. 15, 1930. [Class 38 (iii).] Each unit of a multiple unit machine, for example a printing press, is driven by two synchronous motors, having " stators " 19, 21, and rotors 20, 22. One of the stators 21 is fixed, and the other rotates to drive a press unit 10, the rotors being on a common shaft and fed with direct current 31. The fixed stator 21 is supplied with alternating current of constant frequency 38, and the rotating " stator " 19 with a supply of variable frequency 29. The supply 29 is obtained from an alternator 39 driven at variable speed by a motor 40. In operation, the switch 42 is closed and the speed of the motor 40 is adjusted, by moving its brushes, until the frequency of the alternator 39 is the same as that of the supply 38, a frequency meter being used for this adjustment. Then switches 37, 28, and 60 are closed, and the rotors 20, 22 brought to synchronism, whereupon switches 34 are closed to connect the rotors to their direct current supply. To drive the units 10, the switch 60 is opened, and the frequency of the alternator 39 gradually reduced, so that the "stators" 19 rotate at a speed proportional to the difference between the frequency of the alternator 39, and the supply 38. Specifications 25358/11 and 328,019, [both in Class 35, Dynamoelectric generators &c.] are referred to.