| 摘要 |
PROBLEM TO BE SOLVED: To reduce leakage current which flows from the interior of equipment and a load to a ground line and is propagated through alternating-current power lines, and stably reduce noise. SOLUTION: A zero-phase current transformer 21 detects leakage current, propagating through alternating-current power lines, as a difference between currents passing through lines E1 and E2 at a power conversion circuit portion 3 side than capacitor C7. The detection ratio is '1'. Detected current is induced in a secondary winding of the zero-phase current transformer 21, and an amplification circuit 22 amplifies this current. The amplification factor is '1'. A noise reduction circuit portion 4 supplies the current as compensating current to a ground line through a capacitor C6 in opposite direction to leakage current so that the leakage current is cancelled out. Since the amplification factor of the amplification circuit 22 is '1', oscillation or the like does not occur. COPYRIGHT: (C)2003,JPO
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