| 摘要 |
<p>PURPOSE:To obtain a small-sized light wt. safe zero phase current transformer, by providing an optical fiber wound around the respective phase electric wires of a three- phase distribution line and a signal converter. CONSTITUTION:An optical fiber zero phase current transformer 2A is constituted of the single mode optical fiber successively wound around the respective phase electric wires 1a-1c of a three-phase distribution line 1 in the same direction in the same number of windings and a signal converter 5. The converter 5 has a light emitting element 6, a polarizer 7, a detector 8, a light receiving element 9 and an electronic circuit 10 mounted therein. The light from the element 6 is linearily polarized by the polarizer 7 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. When an earth accident is generated, a zero phase current flows to the distribution line 1 and the magnetic field received by the optical fiber 4 also becomes large in proportion thereto and the plane of polarization also rotates in proportion to the zero phase current at the emitting end of the optical fiber 4. Since the electric signal photoelectrically converted by the element 9 changes corresponding to the zero phase current at the time of the generation of earthing, the zero phase current of the distribution line 1 can be detected.</p> |
