GB117298A - Improvements in and connected with the Control of Electrically Operated Switches. - Google Patents

Abstract

117,298. West & Co., A., and Wise, W. L. July 11, 1917. Master control systems.- Relates to notching relays for controlling the successive operation of contactors in motor-control systems and consists in a construction of relay whereby the initial rush of current passing through a setting- magnet attracts an armature 6 and separates the contacts 10, 10<a> of the relay which are then maintained separated by a second magnet 8 until normal conditions are established in the main current circuit. The contacts of the relay are normally held closed by the spring 11 and in the construction shown, the initially attracted armature 6 acts mechanically on a second armature 7 which carries the contacts 10. The coil 3 of the magnet 1 is a shunt circuit containing also the operating-coil 4 of the contactor 5 and the main control switch 14. When the switch 14 is closed the relay is set in the open position by the attraction of the armature 6 and maintained there by the main current in the coil 9. Subsequently the contactor 5 bridges the contacts 5<b> thereby preparing the circuit of the operating-coil 12 of the contactor 13 which is completed when, by the falling-off in the currents in the coils 3 and 9, the spring 11 brings the relay to the closed position. The closure of the contactor 13 cuts out the first section of resistance and connects a second relay in circuit, this relay being set in the open position, as before, and subsequently closed (when the current has fallen) so as to complete the circuit of the second contactor cutting out the second section of resistance. The complete connexions for a three-phase motor are described in which six sections of resistance are cut out of the rotor circuit in succession bv six contactor switches in connexion with six notching- relays, two additional contactors being employed to provide for forward and reverse running. In a modified construction of relay a single pivoted armature is used carrying the contacts at one end and at the other acted on by the shunt setting magnet and the main current magnet against the action of a spring.