| 摘要 |
<p>An apparatus for controlling the load of an alternating-current electricity supply system supplying power to a plurality of consumers. At each consumer's premises the load (1) is connected to an AC mains (2) via a controllable load switch (3). Across the mains is coupled a frequency measuring means (4, 5 and 6) whose output is compared in comparators (7, 8) with predetermined threshold values stored in limit registers (9, 10). The threshold values correspond to frequencies below the normal frequency of the power supplied. When a threshold value is exceeded due to a fall in frequency, an interrupt signal is provided at the output of one or other comparator, depending on the severity of the fall in frequency. The interrupt signal is extended to an input of a processor (11) which operates the load switch after a predetermined delay provided by delay registers (13, 14) associated with the comparators, and disconnects the load from the mains.</p> |
