| 摘要 |
<p>PURPOSE:To obtain a small-sized light wt. safe zero phase current transformer, by winding an optical fiber around a three-phase distribution line so as to surround the same and connecting a signal converter between both ends thereof. CONSTITUTION:An optical fiber zero phase current transformer 2A is constituted of the single mode optical fiber 4 wound around a three-phase distribution line 1 and the signal converter 5 connected between both ends of the optical fiber 4. The converter 5 has a light emitting element 6, a polarizer 7, a light receiving element 9 and an electronic circuit 10 mounted therein. The light emitted from the element 6 is linearly polarized by the polarizer 7 permitting the passage only of light of a wave component in one direction to be incident to the optical fiber 4. When a magnetic field is applied to the optical fiber 4, the plane of polarization thereof rotates in proportion to the magnetic field applied by Faraday effect. Now, when an earth accident is generated, as the result of the flowing of a zero phase current to the distribution line 1, the circumference integration of the magnetic field surrounding said line 1 becomes the value proportional thereto and the plane of polarization of the linearly polarized light passing through the optical fiber 4 also receives the rotation proportional to the zero phase current and the electric signal photoelectrically converted by the element 9 through the detector 8 also changes to make it possible to detect the zero phase current.</p> |
