| 摘要 |
<p>PURPOSE:To make it possible to measure three-phase A.C. without any error, by connecting a resistance with secondary side of a current transformer in parallel, and also by inserting the resistance in the secondary side of the currect transformer when measuring T-phase and R-phase currents. CONSTITUTION:Resistance R1 and R2 are connected with secondary sides of current transformers 1 and 2, respectively, which are supplied with R-phase current iR and T-phase current iT, and at the same time, an AC ammeter 5 is connected through changeover switches 3 and 4, and resistances R11 and R21 are also connected through changeover switches 13 and 14. At this time, resistances values of the resistances R1, R2, R11 and R21 are appropriately selected so as to satisfy an equation of (R1.R11)/(R1+R11)=(R2.R11)/(R2+R21)= (R1.R2)/(R1+R2). When measuring respective currents of phase of R, T and S, the measurement is performed by turning ON only the switches 3 and 13, the switches 4 and 14 and the switches 3 and 4, respectively. It is possible, by so doing, to prevent secondary side of a non-selected current transformer from being kept open and also to measure alternate current accurately.</p> |
