Development of portable equipment for monitoring currents and voltages of power transmission lines

We propose portable equipment that monitors current and voltage of high-potential power transmission lines. In the equipment, a current and voltage sensor are attached to a hollow insulator that supports a power transmission line. A current of a power line is detected by an air-core solenoidal coil clamped to the power line and the detected current signal is transmitted to the ground station by a modulated LED light through the hollow insulator; a voltage on a power transmission line is detected by a high resistance element, zinc oxide (ZnO) that acts as a potential divider between the power line and the ground. We make an experimental device for 6.6 kV power lines and demonstrate that it can monitor currents ranging from 0 to 600 A and potentials up to 6.6 kV. The proposed equipment is small-sized, light, and inexpensive in comparison with the conventional CT (current transformer) and PT (potential transformer) since it does not require high potential insulators and magnetic cores. Further, the equipment is easily installed owing to its small size and its simple structure.