| 摘要 |
PURPOSE:To compensate detection error in low current region of a measuring current of and to minimize the fluctuation of error due to power factor of load by adding microcurrent having shifted a certain time in phase to the detected output from a current transformer. CONSTITUTION:A voltage of a measuring circuit is impressed to the terminal 1 of a voltage divider 3 and is divided with a determined diversion factor. The divided voltage is impressed to a multiplying element 3 and a dividing circuit 8 for compensating phase. And to the measuring circuit, a current transformer(CT) 4 to detect its current is connected with terminals 2A and 2B. The output current from the divider 8 is so set to a proper value as to compensate the detection error in the region where the current from the measuring circuit is so small that a negative detection error of CT4 becomes not negligible. When the current from the current circuit is small, the output current phase is shifted by properly setting a condenser capacity in the divider 8. By this, a microcurrent is added to the detected output from the divider, the negative error of the divider in low current region is compensated, and fluctuation of error is decreased. |
