GB823554A - Improvements in or relating to electrical control apparatus for machines - Google Patents

Abstract

823,554. Control of motors; controllers. IGRANIC ELECTRIC CO. Ltd. May 2, 1956 [May 13, 1955], No. 13533/56. Class 38 (3). [Also in Group XXXV] An electric motor 12 driving press 10 is started by closing a switch 34 to energize contactors 18, 24 and 22 in sequence. A solenoid 16 is energized to release brake 15 and to couple the press to the motor through clutch 14, by actuating " run " button 36 whereby contactor 24 is de-energized, but contactor 22 is maintained through contact 22a. Such operation actuates contactor 20 for energizing the solenoid 16. After the press-parts have moved to a position in which the operator cannot get hurt; switch 30 closes a maintaining circuit for contactor 20. Upon release of the " run " button, contactor 24 is re-energized. A short time later in the cycle of press operation, switch 28 opens to de-energize contactor 22 so that contact 22c re-establishes the maintaining circuit for contactor 18 across switch 26 which opens later. After a period, press-operated switches 26, 28 re-close in sequence, and, near the end of the cycle of press operation, switch 30 opens to deenergize contactor 20. This causes the press to be un-coupled from the motor and the brake to be applied. The arrangement is such that the press cannot be operated continuously by keeping the " run " button depressed. Moreover, failure of any of the contactors to respond in a correct manner prevents continued operation of the press. The contactor 20 is duplicated by contactor 50 to afford additional protection. Modifications of the part of the system indicated by rectangle 42 are referred to, Figs. 3-6 (not shown).