Development of custom LSIs for protective relays and their evolution to new static relays

A relay LSI and a filter LSI are developed for static distance relays. The relay LSI is based on the phase-comparison scheme and applicable to a reactance relay, a mho relay, an offset mho relay, and an ohm relay. Key technologies used to meet the relay requirements are CMOS switched-capacitor technologies. Circuit compositions and characteristic test results are described. A prototype relay unit demonstrated superiority to a conventional unit in terms of its compactness. High reliability (because of the small number of parts), high accuracy, and very low power dissipation.<
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