| 摘要 |
1,117,309. Signalling over power lines. LONDON ELECTRICITY BOARD, and A. J. BAGGOTT. 9 June, 1966 [9 March, 1965], No. 10026/65. Heading G4H. A data transmission system comprises means for repetitively imposing an interrogating signal on a repetitive waveform, a number of responder stations forming a group, means at each responder station to identify the interrogating signal, means to enable the responder stations to respond in sequence to the interrogating signal, storage means at each responder station and means controlled by the stored data to impose a corresponding identifiable response signal on the repetitive waveform. The invention is applied to meter the maximum demand of several consumers on electric power supplied over lines 24, 25, Fig. 1. Each has a meter 20 which gives an output pulse when a given quantity of electricity has been consumed, e.g. 1 kW- hour. This signal is stored in store 21 which is read out and reset periodically by pulses from a selector 22. If the rated maximum consumption is 20 kW the stores are read-out 20 times an hour. The interrogating signal 38, Fig. 3, is a spike on the power waveform. This is transmitted from the central station and detected at the responder stations. It is used to step each of the selectors 22, which may be ring counter. Each responder station is connected to a different one of the outputs so that the corresponding stores are read out in turn each at a particular differential time. If, since a store was last read-out, a kilowatt-hour has been consumed, the store 21 will be set and in being reset, it applies a spike 39 to the waveform of line 24, the timing of which identifies the responder station. At the control station the interrogating pulses are applied to a counter 32 having an output for each consumer, corresponding gates being enabled at the correct differential times to pass the signals to the store of a computer. The interrogating signal is imposed on the waveform by triggering a thyristor or silicon-controlled rectifier connected across the lines, the triggering signal being derived by phase displacing the carrier waveform and deriving a pulse at the zerocrossing point. A series of interrogating signals is sent out at predetermined intervals as determined by a timing device. Each series contains a number of pulses corresponding to the number of consumer stations to be read. A three-phase system is described.
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