| 摘要 |
PURPOSE:To prevent the secondary winding side of a current transformer from damaging by the high-frequency voltage, by a method wherein the third winding that contains a circulating circuit having a capacitor is wound between the primary and secondary windings. CONSTITUTION:At a commercial frequency, the magnetic flux phi that is produced by a normal current I1 flowing in a primary winding 16 flows in a ring iron core 15, and then a secondary current I2 flows in a secondary winding 18. On the other hand, a current I3 hardly flows in a circulating circuit 22 because the impedance of a capacitor C is high at the commercial power frequency. Therefore, the current I2 is a current corresponding to a current transformation ratio. Next, for a primary current I1 at a high frequency, the impedance of the capacitor C is low, and then almost the entire I3 corresponding to the high frequency current I1 circulates in the circuit 22. Accordingly, the high-frequency voltage by a high-frequency current is inhibited to transfer, and the amount of the secondary voltage V2 can be suppressed. |
