INSTANTANEOUS OVERCURRENT ELEMENT FOR HEAVILY SATURATED CURRENT IN A POWER SYSTEM

摘要

The instantaneous overcurrent element, used in a microprocessor-based protective relay for a power system, includes a finite impulse response filter which generally is a cosine filter and is responsive to the current waveform from the current transformer for fault determination unless the distortion in the current reaches a preselected threshold, at which point a peak detector circuit is used to provide the current magnitude values for fault determination. The RMS value from circuit (88) is compared against the threshold value in comparator (90).