GB376522A - Improvements in controllers for electric motors - Google Patents

Abstract

376,522. Master control of A.C. motors ; controllers. SEEGER, E. W., Wauwatosa, Wisconsin, U.S.A. July 31, 1931, No. 21944. Convention date, Aug. 4, 1930. [Class 38 (iii).] Combination of resistances.-The motor 1 of a printing press has its rotor resistance R arranged in sections the values of which are in geometrical progression, the combinations of the sections being preselected by a switch 13 controlling electromagnetic switches 10, 11, 12. Depression of " run " button 18 causes relays 14, 15 to pick up. Relay 15 completes a maintaining circuit for itself over "stop" and " reverse " buttons 16, 17 and also energizes forward contactor 8. Relay 14 short-circuits sufficient of the rotor resistance R to give the motor the necessary starting torque. Release of " run " button 18 causes relay 14 to open, but completes a circuit, over the maintaining contacts of relay 15, to the switch 13, so that switches 10, 11, 12 are effective to adjust the resistance R to a value selected by the switch 13. If the "run" button 18 is locked in an intermediate position, the circuit for switch 13 is not completed and and the motor runs at low speed with all resistance R in circuit. "Inch" button 19 when depressed causes closure of relay 14 and forward contactor 8, but opens both upon release. Similarly "reverse" button 17 controls relay 14 and reverse contactor 9.