| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a ZCT which can measure a ground fault current with a high precision by reducing residual current, which will increase as the frequency increases, for experimental researches which are recently performed in terms of early detection at a ground fault accident to determine the causes and point of a ground fault accident on the basis of a high-frequency portion included in zero-phase current generated at the ground fault. <P>SOLUTION: To make residual current flow only through the coil as a cyclic current when the frequency of each primary current increases, the inside and outside of the coil are covered with thin copper sheets so that the coil is sandwiched between the thin copper sheets. This makes the copper thin sheets be at the same potential, and induced voltage with a different phase generated from each primary current by a leakage flux arising from residual current will pass through the capacitance between the thin copper sheets at the same potential and the coil. Thus, cyclic current flows, preventing an increase in residual current without adversely affecting zero-phase current characteristics. <P>COPYRIGHT: (C)2004,JPO&NCIPI</p> |
