Patent GB-1439788-A (GB)
Title: Sealed electrical contact unit capable of being magnetically actuated and arrangement tehreof
IPC: H01H67/30
Filed: 1973-11-29
Abstract: 1439788 Electromagnetic relays INTERNATIONAL ELECTRIC CORP 29 Nov 1973 [1 Dec 1972] 55318/73 Heading H1N A sealed contact unit Fig. 2 which is magnetically actuated, has a flanged cover 1 attached to co-planar base plate assembly comprising a ring-shaped outer portion 2 and a disc-shaped inner portion 3 joined by a non-metallic ring and a flat armature contact 5 is mounted to the cover by a spring 6 so as to face part of the inner portion and part of the outer portion of the base plate. The base disc 3 is made of magnetic material and different modes of operation with the contact attached to the cover at 7, Figs. 4 and 6, are achieved by selecting magnetic or non-magnetic materials for the base ring 2 and for the cover 1 as well as by arranging for the cover to be assembled in a 180 degree manner (Figs. 5, 7, not shown). The contact unit can be used in many ways in electromagnetic relays. With stacked units located between flux guides (12, 13) formed by the arms of a U-shaped electromagnet (11) (Fig. 8, not shown) or with juxtaposed units between the arms of an H-shaped electromagnet (Fig. 9, not shown) the coils of the electromagnet being wound on the base of the U or on the cross-bar of the H, a variety of "neutral" (i.e. non-holding and non-polarized) relays can be obtained. In Fig. 10, and similarly in Figs. 12, 13 (not shown) two contact units 21, 22 have their base plates facing one another with an electromagnet 24, 25 located between the opposed discs 3 and with a permanent magnet 23 between the opposed outer rings 2, the resulting arrangement giving shunt and series characteristics with the permanent magnet providing a degree of pre-excitation. If the pre-excitation is less than the release excitation a "neutral" relay with reduced operating and release values is obtained; if the pre-excitation exceeds the hold value the relay is bi-stable, and if the preexcitation exceeds the operation excitation of the "neutral" relay there is obtained a relay with break contacts. With the magnet 32 designed for use in a magnetic holding relay as exemplified by Fig. 10 the outer rings of the bases of the contact units 21, 22 are magnetic and with the contacts of the units initially open the majority of the flux of the magnet passes between the two base plates in a shunt manner through the air path 26. A short duration excitation of the electromagnet 24, 25 produces a magnetic flux in series with that of the magnet 23, a considerable amount of which flows through the armatures 5 which are then attached flatwise to their base plates for retained contact closure. The armature contacts are released in response to a short duration excitation of the electromagnet in the opposite direction. An arrangement with two contact units facing one another and with an external U- shaped flux guide (46) magnetically connecting the base discs 3 which functions as a holding relay is described (Fig. 17, not shown) and in a further embodiment of a magnetic holding relay, Fig. 18, there are two central portions 50, 51 to a flux guide 49 on each of which is wound a coil 52, 53 for control by co-ordinates X, Y, of a crosspoint matrix there being no coil on the magnetic core 24 between the contact units. This last embodiment can be actuated by short-duration simultaneous excitation of both coils 52, 53 in the same sense to produce magnetic flux in series with that of the permanent magnet 23 in order to close the contacts of the units 47, 48. If only one coil is energized then the flux produced is short-circuited by the other leg but the contact armatures 5 are held both in the open or in the closed position by the flux of the permanet magnet. In relay embodiments the oppositely arranged contact units are insulated from one another by foils or a plastics coating.