GB647843A - Electromagnetic relays - Google Patents

Abstract

647,843. Electromagnetic relays. WESTERN ELECTRIC CO., Inc. Jan. 23, 1948, No. 2126. Convention date, Feb. 24, 1947. [Class 38(v)] A relay with a slow action has a core 10 carrying an operating winding 1 and shortcircuited coils 14 and an amature in the form of a frame with cross pieces at 64, 48 and 42 is pivoted at 64 so that air gaps pulling the armature in opposite directions are provided between the core and the cross pieces at points 53 and 43 lying on opposite sides of the core. The hinge at 64 includes a separating layer of non-magnetic material which may take the form of washers. The cross piece 42 is bent as shown in Fig. 3 and carries a member 58 which operates the studs 63 which operate the two sets of contact springs arranged on the two sides of the relay. Fig. 2 shows the relay operated. On de-energization a spring 54 helped by the contact springs returns the armature quickly to its other position, Fig. 3. On re-energizing the winding 1 the flux traversing the core and armature consists of a permanent steady flux due to the winding and a transient ever diminishing flux due to the induced currents in the short-circuited coils 14. The latter flux opposes the former, the net result being that to start with nearly all the flux from the magnet 1 passes over the air gap 53, now at its smallest, and none passes through the hinges 64. The attraction at the air gap 53 thus overpowers the attraction at the gap 43, now at its largest. As the transient flux diminishes flux passes more and more through the hinge 64 and less through the gap 53 so that eventually the flux at the gap 43 overpowers the flux at the gap 53 and the relay operates: Adjustment for different times of delay is effected by adjustment of the air gap 53 and by adjustment of a disc 20 of magnetic material which serves to divert some of the flux from the air gap between 10 and 43.