LED-POF Compound as Current Sensor for High-Voltage Transmission Lines

Abstract

Transmission line and substation operators need to know the electrical currents circulating in their equipment to control energy demands, short-circuits, excess heating, and impulsive surges. Nevertheless, current transformers are bulk, heavy with a large footprint, making them difficult to install. Optical current transformers based on the Faraday effect on optical fiber reached the market but employed complex and expensive technology. In this paper, we describe an optoelectronic high-voltage current sensor applying a LED as a current sensor and a plastic optical fiber (POF) as a link to the ground potential. This system was tested in two field applications: A current transformer for in-field surveys at 13.8 kV distribution lines and to measure leakage currents in 500-kV high-voltage insulators. In a conclusion, the systems described in this work demonstrated to be portable, cheap, and easy to install, presenting advantages such as they do not require in-situ energization, the POF transmitting media guarantees electromagnetic immunity as well electrical isolation between high voltage potential and the ground potential, and the possibility to install in live-line.