GB562461A - Improvements in electromagnetic relays - Google Patents

Abstract

562,461. Electromagnetic relays. PLESSEY CO., Ltd. March 19, 1943, No. 4520. Convention date. March 19, 1942. [Class 38 (v)] In a relay responsive to a special frequency of alternating or intermittent current, two reeds 13, 14 having the same natural period of vibration and carrying armatures or magnets 16, 17 arranged near the pole 11 of the electromagnet 12, vibrate towards and away from each other to close and open. contacts 18, 19. If the reeds vibrate at 60 cycles per second they will thus be responsive to an intermittent current of 60 pulses per second or to an A.C. current of 30cycles. The relay can be made responsive to A.C. of 60 cycles by having a second polarizing winding energized by D.C. current on the pole 11, Fig. 4 (not shown). This will convert the A.C. into intermittent D.C. current of 60 cycles. The same arrangement can also be made responsive to intermittent D.C. of 30 cycles by arranging the polarizing winding in opposition and so producing A.C. of 30 cycles. By utilizing the above principle, the same relay can be made to operate under current of one frequency, which operation will then make it selective to current of double the frequency. A circuit may also be made responsive to a combination of frequencies by use of two relays. In a modified form of relay, Fig. 3 (not shown), permanent magnets replace the armatures 16, 17. U.S.A. Specification 2,190,685 is referred to.