ZERO-PHASE CURRENT DIFFERENTIAL RELAY

WIPO Patent Application WO/2022/149256

A1

This zero-phase current differential relay (40) comprises: a first differential amount calculation unit (210) for calculating a first differential amount on the basis of neutral point current and zero-phase current based on each phase current; a current change detection unit (230) for detecting a change of each phase current; and a first suppression amount calculation unit (220) for calculating a first suppression amount on the basis of the detection results of the current change detection unit (230), each phase current, and the neutral point current. The first suppression amount calculation unit (220) calculates, for each phase current, a subtraction current obtained by subtracting the phase current at a cycle before the present cycle from the phase current at the present cycle and, when the change of each phase current is detected, calculates, as a first suppression amount, a first maximum value among the effective value of the subtraction current of each phase and the effective value of the neutral point current. The zero-phase current differential relay (40) further comprises an operation determination unit (240) for outputting a protection signal for protecting a three-phase transformer when the first differential amount and the first suppression amount are present in an operation region.

WATASE REIJI (JP)
ODA SHIGETO (JP)

PCT/JP2021/000456

July 14, 2022

January 08, 2021

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MITSUBISHI ELECTRIC CORP (JP)

H02H7/045; H02H3/28

JP2019030073A	2019-02-21
US20120140365A1	2012-06-07
JP2016010223A	2016-01-18

FUKAMI PATENT OFFICE, P.C. (JP)

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