서지방호장치의 접지도체에 유도되는 전압이 방호성능에 미치는 영향

초록

Surge protective device(SPD) is installed to discharge surge voltages and currents invaded to communication or power lines to the ground. The protective performance of SPDs depend on methods of connecting the grounding conductors of SPDs and equipment to be protected. This paper presents experimental results of effects of induction voltage from grounding conductors of SPDs on their protective performance. The protective effects of SPDs were investigated in cases where the grounding conductor is connected to the grounding terminal close to SPD or equipment. Also electrostatic and electromagnetic induction voltages to communication or power lines from grounding conductor of SPDs were examined. As a result, the residual voltage between the power line and grounding terminal of equipment to be protected is significantly higher than the clamping voltage of SPD when the grounding conductor of SPD is connected to the grounding terminal close to the equipment due to the induction of grounding conductor. However, the residual voltage is minimized when the grounding conductor and communication or power lines are installed very close to each other. The impulse voltages caused by electrostatic and electromagnetic induction to communication or power lines from the grounding conductor of SPDs were decreased with increasing the distance between the grounding conductor and communication or power lines.

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