| 摘要 |
An electronic tripping device for low-voltage circuit-breakers comprises means for detection and calculation of a ground-fault current operatively connected to tripping means of said circuit-breaker. The means for detection and calculation comprise: current-sensor means, which supply, for each pole, a signal proportional to the current; means for detection of the sign of the current, which, for each pole, supply a signal representing the sign of the current; current-rectifying means, which, for each pole, supply a rectified signal proportional to the current circulating in said pole; and first numerical-processing means, which supply a value with sign representing a ground fault by means of a numerical-processing operation comprising the multiplication of the signal representing the sign by the corresponding rectified signal.
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