| 摘要 |
PROBLEM TO BE SOLVED: To provide a surge protection device which detects the destruction of a varistor quickly and automatically. SOLUTION: The surge protection device 50 includes: a zinc oxide type varistor 3, which absorbs a surge current flowing in a circuit; a light-emitting means 4; a light-detecting means 7, which detects the presence of light 8 emitted from the light-emitting means 4; interruption pieces 5a, 5b, which advance and retreat between an interruption position where the light 8 is interrupted and a non-interruption position where it is not interrupted; a spring member 2, which elastically urges the interruption pieces 5a, 5b toward the interruption position; a low-melting point metal alloy 12, which joins the interruption pieces 5a, 5b in resistance to the elastic urging force of the spring member 2; and an accommodation casing 1, which includes openings 10, 11 for holding the varistor 3 and the spring member 2 for positioning and passing the light 8 emitted from the light-emitting means 4 for the light-detecting means 7 to receive it. COPYRIGHT: (C)2010,JPO&INPIT |
