| 摘要 |
487,077. Electric control systems. RUSSELL, W. F. Feb. 17, 1937, No. 4771. [Class 40 (i)] In a system for operating electric power devices such as lamps, water heaters &c. from a remote station over the power transmission network, the devices are operated in turn in response to successive signals of like polarity. As shown, two A.C. power circuits POD2, POD2 are controlled by polarized relays A, B operated in response to D.C. pulses transmitted from a control station. The relay A is normally connected across the line but the circuit of the relay B is normally open at the contacts M of a time-delay relay D, W of watt hour meter type having current and pressure coils CC, PC. Upon reception of the first pulse relay A is operated to switch on the power circuit POD1 and at contacts a1 reverse the polarity of the current in coil CC so as to drive the disc W until projection P engages stop S2 and operates contacts M to prepare the circuit of relay B for operation by the next pulse. In order to disconnect the circuits POD1, POD2, a pulse of opposite polarity is transmitted to restore relays A, B, the restoration of relay A effecting a reverse drive of the disc W to open contacts M. In a modification, all the power circuits may be switched on simultaneously and switched off in turn in response to successive signals.
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