GB353816A - Improvements relating to electric motor starting systems - Google Patents

Abstract

353,816. Master control of several motors. SUNDERLAND FORGE & ENGINEERING CO., Ltd. and PFOB, S., St. Luke's Road, Pallion, Sunderland. Dec. 17, 1930, No. 38078. [Class 38 (iii).] In a starting system for a number of motors in which each motor in turn is first connected to a common starter, and when up to speed is transferred to the supply mains, a common resistance is provided so that when an attempt is made to start two or more motors simultaneously or to start one motor before a second has been brought up to speed, the current is insufficient to operate the motor contactor coils. When a button A is pressed, coils s, n are energized by a circuit passing through the common resistance K. Switches S<1>, N<1>, W close, and the motor M receives current through a starting resistance R. When the switch S<1> closes auxiliary switches s<1>, s<2> close, the former completing a maintaining circuit for the coils u, s through a coil t, independent of the button A. The switch T therefore closes to energize coils V, E, the former actuating the plunger v<1> to cut out the resistance R at a rate regulated by the coil E. When all the resistance is out and the motor M is up to speed, contacts 13, 14 are closed and a circuit is completed for a coil p through switch s<2> and resistance K. As a result the switches P<1>, p<1> are actuated, the former placing the motor M across the supply mains and the latter de-energizing the coil s but closing a maintaining circuit for the coil p, n. When the switch S<1> opens switches s<1>, s<2> also open, the former de-energizing the coil t and breaking the circuit for coils V, E, so that the apparatus is ready for starting a second motor. Specification 324,360, [Class 38 (iii), Electric motor control systems &c.], is referred to.