Lightning Surge Response Improvement by Combinations of Varistors and Gas Discharge Tubes

摘要

This paper proposes a new methodology for protecting power apparatuses against overvoltage or overcurrent caused by lightning surge. Surge Protective Devices (SPDs) are used for protecting apparatuses against overvoltage or overcurrent caused by lightning surge. SPDs are mainly divided into two categories. One is clamping type and the other is switching type. Typical clamping type SPD is a variable resitor (varistor). Typical switching type SPD is a Gas-filled Discharge Tube (GDT). Both varistors and GDTs have problems when using them alone. Therefore both a GDT and a varistor are normally connected in series or parallel. However these simple connections of them have still problems. This paper proposes a lightning surge response improvement by combinations of both varistors and GDTs in order to solve the problems of them. It is that three or more GDTs are connected in series and two or more varistors are connected in parallel. This new methodology has already beeing filed as patents in many countries. The proposed methodology could solve the problems of conventional combinations of a GDT and a varistor.