GB480455A - Improvements in or relating to means for delaying the response of electro-magnetic switches - Google Patents

Abstract

480,455. Electromagnetic switches; master control of D.C. motors. WEST & CO., Ltd., A., and BREEZE, V. Sept. 14, 1936, No. 25034. [Classes 38 (iii) and 38 (v)] The armature 15 of an electromagnetic switch is, at the non-attracted position, subject to control by an electromagnetic control device which, without positively impeding the movement of the armature towards its attracted position, determines, by the degree of energization of its winding 8, whether the armature 15 occupies an intermediate or an extreme non-attracted position, at which it respectively can or cannot be moved to the attracted position by its operating winding 5a. In the construction shown in Fig. 2, when the control winding 8 is energized, its armature 17 is attracted and an arm 19 is moved to the right to permit the armature 15, which is pivoted at 16, to move to'the extreme position shown in broken lines. When the winding 8 is de-energized, its armature 17 drops, and the arm 19 moves the armature 15 to the intermediate position in which it can be attracted by the winding 5a. In the arrangement shown in Fig. 1, three of the switches are provided, having closing windings 5a ... 7a, contacts 5 ... 7 adapted to short-circuit sections 2 ... 4 of a starting resistance, and control windings 8 ... 10. On closing a switch 11, a winding 12a is energized to close a main contactor 12 which connects the motor 1 to the line through the resistances 2 ... 4. The windings 8 ... 10 are simultaneously energized, so that the armatures of the electromagnetic switches are in their extreme '' off " positions. The contact 5 has auxiliary contacts 5b, which close when the contact 5 is in the extreme " off " position and energize a winding 14a which closes a discharge circuit for the winding 8 at 14, a maintaining circuit for the winding 14a at 14b, and energizing circuits for the windings 5a ... 7a at 14c. As soon as the winding 8 is deenergized, contact 5 closes to short-circuit the resistance section 2 and the winding 9 ; the latter then discharges and after an interval permits the contacts 6 to close to short-circuit the resistance section 3 and winding 10. As soon as the current in the winding 10 has died down, the contact 7 closes to short-circuit the resistance section 4.