| 摘要 |
PURPOSE:To accurately integrate minute input signals, by removing offset voltage by drawing DC voltage signals that are proportional to input currents, absolute values being equal and the polarity differs at the secondary side of a power transformer. CONSTITUTION:A rectifying circuit 22 consisting of diodes D1-D4 and current- voltage converting elements Ri1, Ri2, Ci is mounted at the secondary side of a current transformer 21 installed to a feeder, and DC voltage is signals ep, en that are proportioned to AC input currents, the absolute value is similar and the polarity differs and drawn between the output terminals. The signals, ep, en are alternately supplied to an integration circuit 24 by means of a switch 23, the output of a comparator 25 is inverted every time integration output reaches fixed voltage and the switch 23 is changed over in response to inversion output. Thus, frequency fo formed by the inversion output of the comparator 25 proportional to the AC input currents. |
