Deterioration warning functional attachment SPD

摘要

PPROBLEM TO BE SOLVED: To improve reliability by correctly grasping the deterioration of a protection element. PSOLUTION: An SPD with a deterioration alarm function comprises: varistors 8 to 11 connected between power supply terminals 1 to 3 and a ground terminal 4; a gas arrestor 12 connected between the varistors 8 to 11 and the ground terminal 4, and having a discharge gap; and a photo transistor 17 disposed close to the gas arrestor 12, and detecting light emission at the time of the discharge of the gas arrestor 12 due to a surge current. The SPD also comprises a CPU 18 for determining whether output from the photo transistor 17 exceeds a threshold value set on the basis of the light-emitting time of the gas arrestor 12 or not, and an alarm lamp 20 for displaying a deterioration alarm on the basis of the output of the CPU 18. PCOPYRIGHT: (C)2012,JPO&INPIT