METHOD FOR MEASURING ZERO PHASE CURRENT BY USING ELECTRO-OPTIC EFFECT ELEMENT

摘要

PURPOSE:To surely insulate electro-optical effect elements against ground potential and to make measurement by disposing search coils to the respective side faces of a three-phase aerial distribution line, impressing an induced voltage to the electro-optic effect elements of an optical voltage sensor and making electrical conversion through an optical fiber. CONSTITUTION:The search coils 1, 2, 3 are disposed in proximity to conductors R, S, T of the three-phase aerial distribution line. The voltage sensor 5 is assembled in a housing 4 consisting of an insulator and the housing 4 is supported by a support 29 which is supported by a pole 22. The sensor 5 is constituted by linearly disposing 3 pieces of the electro-optic effect elements 7 and a quarter wavelength plate 8 between a polarizer 6 and an analyzer 9. Light is applied by the optical fiber 10 to the polarizer 6 and the fiber 11 for photodetection is disposed on the exit side of the analyzer 9. The other ends of the fibers 10, 11 are connected to a signal processor 12. The processor 12 is disposed on the ground or in the position near the ground. The measurement is thus made by surely insulating the sensor against the ground potential.