| 摘要 |
498,640. Electromagnetic relays. BRITISH THOMSON-HOUSTON CO., Ltd. March 18, 1938, No. 8421. Convention date, March 20, 1937. [Class 38 (v)] [Also in Group XXXVIII] A relay connected to a supply circuit and responding to a ripple superimposed on the supply in order to close a circuit after attaining a predetermined amplitude of oscillation, comprises a rotary member F controlled by a pair of coils A, B after the manner of an induction motor, the effect of the coils being normally in balanced opposition. Coil B is fed by the secondary of a transformer T, the primary of which is in series with a saturated choke so that any variation of the supply voltage has a greater effect on coil B than on coil A. The member F is thus set in oscillation, controlled by spring R, at the frequency of the ripple and ultimately makes contact at G, I ; H, K to operate a relay S which closes lamp circuits &c. The Specification also refers to a relay comprising a solenoid with a spring-loaded oscillating core.
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