GB740033A - Speed-indicating and automatic control system for electric motors - Google Patents

Abstract

740,033. Control of several motors. FORGES ET ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE JEUMONT. March 22, 1954 [March 27, 19531, No. 8283/54. Class 38(3) [Also in Group XXXVIII] The speed of a main motor 1 is indicated by the position of a contact arm 24 movable over a potentiometer 17 to regulate the speed of an auxiliary motor 12 to equality with that of the main motor, the contact arm being driven in accordance with the difference of the motor speeds through a differential mechanism. The differential sun-wheels 7, 11 are driven by the respective motors 1, 12 through electromagnetic clutches 6, 13 and various controls are effected as a function of the speed of the main motor by de-energizing one or the other of these clutches. Thus, rocking a brake lever 9a de-energizes the winding 8 of clutch 6, and locks the sun-wheel 7, whereby the contact arm 24 is driven by the auxiliary motor at a continuously decreasing speed to the position a where it closes limit contacts 26 which may de-energize the main motor armature 3 and operate a brake 5 to stop the motor. The closure of contacts 26 may also act on the generator supplying the main motor or upon various safety or signalling devices to produce precise slowdown and stopping of the load 2, e.g., a mine hoist, driven by the main motor. The motor 1 may be reversible, in which case a reversing device 28 is provided for the auxiliary motor. Similarly, by using the brake 15a to disengage clutch 13 and lock the sun-wheel 11, the contact arm 24 is driven at a speed corresponding to that of the main motor to position e to close limit contacts 27. This closure may control various safety operations and initiate the slow-down of the main motor.