| 摘要 |
<p>PURPOSE: To reduce an adverse influence that the motion of a cable gives to the accuracy for measuring current by providing a light port, an optical cable, and a photodiode. CONSTITUTION: A switch 60 is in closed position and a switch 62 is in open position during one half of each switching cycle, and light advances from an LED 24 to a photodiode 28 via a cable 16, ports 12 and 14, and a cable 18. Also, during the other half cycle of each switching cycle, light advances toward a photodiode 30 from an LED 26 via the cable 18, the ports 14 and 12, and the cable 16. Then, by applying the output of a circuit 40 to an inverter 50, signals applied to a low-pass filter 66 during the alternate half cycle of the switching sequence contain +e and -e noises, and the noises can be suppressed by setting the cut-off frequency of the filter 66 to a switching frequency or less.</p> |
