| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power measuring device improved in reliability. <P>SOLUTION: Interface voltages Vab, Vbc and Vca among a, b and c phases of a power generator 2 are measured with single-phase VTs 3a to 3c, and line currents Ia, Ib and Ic are measured with CTs 4a to 4c. On the basis of these interface voltages and these line currents, six patterns of single-phase power, that is, WA1=Vab×Ia; WA2=Vba×Ib; WB1=Vbc×Ib; WB2=Vcb×Ic; WC1=Vca×Ic; and WC2=Vac×Ia, are obtained by power conversion devices 5a to 5c. VT abnormality determination means 6a of an arithmetic unit 6 determines abnormality of the single-phase VTs 3a to 3c on the basis of differences among the six patterns of the single-phase power. When it is determined that any of the VTs is abnormal, three-phase power is obtained from a sum of prescribed two single-phase power out of the six patterns of the single-phase power, and hence, the power measurement may be continuously performed, resulting in improving reliability. <P>COPYRIGHT: (C)2012,JPO&INPIT |
