| 摘要 |
PURPOSE:To equalize each current value input to a relay body and reduce an error and to improve the accuracy of detection by correcting the secondary currents of a current transformer by using a matching coefficient computed from the primary-side tap voltage and secondary rated voltage of a transformer and the ratio of current transformation of a current transformer and correcting the secondary currents of the current transformer. CONSTITUTION:The secondary rated voltage V2 of a transformer LRT, each ratio of current transformation ct1, ct2 of current transformers CT1, CT2 and the values of a plurality of primary side tap voltage V'1 are input previously from a setting panel 5, and stored beforehand in a memory, etc., in a device. A microcomputer selects the value of tap voltage V'1 of interest in response to a tap positional signal S1 successively input during the operation of the transformer LRT, and computes a matching coefficient KC1 in succession from the value of the tap voltage and voltage V2 and the ratios of current transformation ct1, ct2 and sets it to a multiplier 2 while setting a matching coefficient KC2 (=1) to a multiplier 3. Accordingly, currents I''1 passing through the multiplier 2 are equalized to currents I''2 passing through the multiplier 3 at all times regardless of the position of a tap for the transformer LRT, thus reducing the error of a current value.
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