Development of monitoring equipment of currents and voltages of power-transmission lines

The authors propose portable equipment that monitors a current and potential of 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 on a power line is detected by an air-core solenoidal coil clamped to the line and the detected current signal is transmitted to the ground station through an LED light which travels inside the hollow of the insulator. A potential 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. The proposed equipment may be available for the remote current and voltage measurement based on field detection owing to its small size and its simple structure. The authors demonstrate, experimentally, that the proposed equipment measures currents ranging from 0 to 600 A and potentials up to 6 kV of three-phase 6.6 kV power distribution lines.