Magnetic fields in a Faraday-rotator underneath a high-voltage transmission-line conductor

The progress of a research program aimed at measuring the line current of a high-voltage transmission-line conductor is reported. An optical technique is proposed based on the Faraday effect in an appropriate sensor (Faraday rotator) placed in the magnetic field of the conductor. A laser beam is the only connection between this sensor and the measuring instruments placed at ground potential. A numerical method for the analysis of the magnetic field is presented, based on a simulation technique. The simulation technique is used to represent the current carrying conductor, earth return current and Faraday rotator by sets of fictitious current filaments which satisfy the boundary conditions of the system