| 摘要 |
<p>PURPOSE:To prevent the effect of electrostatic induction by the primary conductor by a method wherein the electrostatic shield for the primary conductor is installed on the secondary coil of an air-core current transformer. CONSTITUTION:An electrostatic shield 3 is attached on the side of the primary conductor 1 of an air-core secondary coil 2. When a current is applied to the conductor 1, the induction voltage corresponding to the voltage of the conductor 1 is induced on the shield 3 by electrostatic induction, and the voltage corresponding to the conductive current of the conductor 1 and that of the phase lagged by 90 deg. is induced on the coil 2 by the electromagnetic coupling. Then, as the shield 3 is earthed, the coil 2 is not subjected to the influence of electromagnetic induction. Accordingly, the in-phase voltage signal corresponding to the conductive current of the conductor 1 can be obtained by having the signal induced between the two terminals of the coil 2 integrated by an integrator 4.</p> |
