| 摘要 |
<p>PURPOSE:To obtain the magnitude of an earth current by digital display, by providing a modulation circuit for modulating the output signal from a comparator on the basis of a synchronous pulse signal, a light emitting and flashing circuit, a photoelectric circuit, a counter and a calculation circuit for calculating an earth current value. CONSTITUTION:The synchronous pulse of a clock pulse generator 9 is counted at each time when a shift register generates random numbers and the analogue quantity (er) of M-series random numbers from a D/A converted 2 is compared with a.ig (a is a constant control coefficient), obtained by correcting an earth current (ig) by a correction device 8, by a comparator 3. When a.ig>=er is formed, an output signal is generated from the comparator 3, and said signal and synchronous pulse signal are modulated by a modulator 4. The modulated signals are photoelectrically converted by a photoelectric converter 11 through a light emitting and flashing circuit 10 to be judged and separated by a judge and separation device 6 to be inputted to counters 51, 52. The number of output signals and the number of synchronous pulse signals are counted by the counters 51, 52 and an earth current is calculated by a calculation circuit 12. By this method, the magnitude of the earth current is obtained by a digital display.</p> |
