| 摘要 |
The energy supplied by the network to each consumer installation (20) is measured in a control unit (1) by tariff metering (5) comprising a power section (2) with an integrator (3) in conjunction with a memory (4). The unit also includes a communications module (7), transmitting data and receiving commands to and from the network's central management unit over power line carrier circuits (31), incorporated in the network, a memory (8) into which the management unit places and updates a threshold power setting, and a comparator (9) with output to an interruptor unit (14). The latter interrupts the consumer's supply through a circuit-breaker (13). This has a thermal delay feature (11), catering for short-term overloads, e.g. motor starting, whose characteristics are simulated by a filter (6) in the measured load input to the comparator to reflect the primary circuit conditions. An instantaneous overcurrent trip (12) is also fitted. The set threshold for each consumer's power demand, held in the control unit memory (8), is related to the network daily load curve, being reduced at peak load times and raised off-peak. Opt., the controller is arranged to initiate an audible or visible alarm as the threshold is approached; the consumer can then reduce his load to anticipate the interruption which will otherwise follow. Opt., also, the circuit-breaker controls selected load elements rather than the whole installation load.
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