GB324360A - Improvements in and relating to electric motor starting apparatus - Google Patents

Abstract

324,360. Allan, J. E. Aug. 24, 1928. Master control systems, electromagnetic; systems &c. depending on the use of two or more motors; automatic starters. - Two or more motors of a group are arranged with a single common starter and separate control switches for each motor, so that the motors can be started one after another in any order, each motor after its own starting operation is completed, being disconnected from the common starter and being connected across the supply mains. Fig. 1<A> is a simplified diagram of one arrangement according to the invention, in which a resistance R and electromagnetic contactors R, R<2>, R<3> are connected between a negative main N through either of two motors M<1>, M<2> to a positive main P. Each motor has a push-button switch A and when either of these is closed, electromagnetic switches N<1>, S<1> join the corresponding motor to the mains through the resistance; the closure of the push-button also by means of a relay T determines the closure of the first contactor R<1> and the subsequent closure of the second and third in succession. By opening contacts t<1>, t<2> the relay prevents premature starting of the second motor. Suitable hold-on connections :for the contactors and the relay are formed through auxiliary contacts not shown in the Figure. The closure of the last contactor energizes the closing magnet of a switch P<1> which connects the corresponding motor across the mains, and causes the opening of the switch S<1> and the return of the relay T. The second motor can then be started in like manner. In a modification the starting resistance is cut-out by a moving contact-member actuated by a solenoid core fitted with retard:.ng means such as an eddy-current brake; the movement of the solenoid-core proceeding automatically, after the closure of a relay, until all resistance has been excluded and the corresponding motor has been put across the mains; and afterwards moving back to the original position ready for the starting of the next motor. The arrangements may be adapted for use with AC. motors, for example, induction motors with rotor resistance. The invention is stated to be applicable to motors driving auxiliary machines in marine engine rooms.