| 摘要 |
A protective relay receives current and voltage inputs, digitizes them and reduces the effects of high and low frequency noise. In the case of a distance relay, incorporated in the relay is a signal generator which generates "operate" and "restraint" sinusoidal signals. In the case of a current or voltage relay, operate is a digitized version of current (voltage) and restraint is a pre-specified constant. In all cases, a magnitude comparator, implemented using short (two sample) data window algorithms, compares the magnitude of the operate and restraint signals and outputs a trip condition signal. The trip condition output is limited to a finite number of values by a limiter system and sent to an adaptive trip counter system. The adaptive trip counter system employs trip counter processing, which determines whether a trip signal will be initiated, immediately or after a period of delay.
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