| 摘要 |
518,621. Signalling over power circuits. SANGAMO WESTON, Ltd., GILLIVER, G., and TAGG, G. F. Aug. 26, 1938, No. 25133. [Class 40(i)] Unidirectional signal impulses are applied to a power main via a transformer. As shown, the operation of a key 5 connects the battery in one or other direction across the transformer primary 2 and connects the secondary 7 between the neutral wire and the main 10. At the same time a normally energized contactor switch 15 is released to remove a shunt from a resistance 12 which is connected in the neutral wire and an impulse is applied across this resistance from another secondary winding. The key contacts are arranged to operate in succession. to prevent the transmission of a reverse impulse when a key is released. Condenser 26 enables a small battery to be used. Specification 518,620 is referred to. |
