Electronic circuit breaker using digital circuitry having instantaneous trip capability

Abstract From the Canadian patent

Instantaneous trip capability is provided to an electronic circuit breaker, which is of the type that generates trip signals by accumulating squares of power line current samples and thresholds the accumulation results. Samples of power line current are taken directly from the current transformer and analog-to-digital converter cascade generating them. The analog-to-digital converter is of an oversampling type, using a delta-sigma modulator. The samples are threshold detected against a prescribed threshold value without previous squaring, integration and detection. The threshold detector result is checked for two consecutive overcurrent indications before an instantaneous trip signal is …