Countermeasures for Controlling Lightning-Caused Overvoltage on Indoor Wiring with Communication Line

Abstract

Overvoltage generated by lightning is a threat to indoor electrical equipments in information-oriented and computerized society. Countermeasures for preventing the overvoltage on an indoor wiring are demanded. Therefore, we have investigated the effectiveness of some countermeasures, such as low-voltage arresters, communication line arresters, SPDs and a common grounding wire, for reducing the overvoltage on an indoor wiring with a communication line. Especially, we have studied the effect of the combination of these countermeasures and their layout on controlling the overvoltage, using a full-scale test distribution line with a customer's facility. Main results are as follows:
(1) A common grounding wire installed along the low-voltage indoor wiring is more effective for reducing the overvoltage on the indoor wiring with a communication line more than that installed under the floor, when the arresters are installed at the panel board.
(2) Combination of a SPD and another countermeasures, such as low-voltage arresters and a common grounding wire, is effective for controlling the overvoltage on the indoor wiring, and the effectiveness of these countermeasures for preventing damage of electrical equipment has been verified by the experiment using actual electrical equipment.