| 摘要 |
PURPOSE:To reduce a leakage current to a value close to zero by supplying a current of an opposite phase to a ground line with respect to a leakage current flowing to ground through the said earth wire of a noise filter from a non-grounding wire of a commercial AC power supply. CONSTITUTION:A primary winding 27 of a transformer 26 is connected to a non-ground line 22 and a ground line 23. The polarity of a secondary winding 28 is reversed to that of the primary winding and the one terminal is connected to the ground line 23 and the other terminal 30 is connected to a ground wire 24 through a capacitor 29 in series. A voltage at the terminal 30 of the secondary winding 28 is a voltage of the opposite phase to that of the non-grounding line 22 and a current 31 flows through the capacitor 29. When a turn-ratio of the transformer 26 is 1:1 and the capacitance of the capacitor 29 is the same as that of the capacitor 13, the leakage current 21 and the current 31 are the same and the leakage current flowing to the ground wire 24 is made zero. When the turn ratio of the transformer 26 is not 1:1, the leakage current 21 and the current 31 are made the same by selecting the capacitance of the capacitor 29 thereby making the leakage current flowing to the earth wire 24 zero. |
