| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a protective relay that can make an accurate operation determination even if a system fault current including a DC component flows. <P>SOLUTION: The protective relay according to an embodiment includes: an input current transformer for transforming the magnitude of an input current and outputting it as an analog signal; an analog converter circuit for converting the analog signal output from the input current transformer into a predetermined analog signal indicating a predetermined analog signal; an A/D converter circuit for converting the predetermined analog signal converted by the analog converter circuit into a digital signal; an arithmetic processing circuit for performing arithmetic processing based on the digital signal converted by the A/D converter circuit; and a relay output circuit for operating a contact output in accordance with the arithmetic result of the arithmetic processing circuit. The analog converter circuit receives the analog signal output from the input current transformer via a negative resistance circuit having a negative resistance value. <P>COPYRIGHT: (C)2012,JPO&INPIT |
