| 摘要 |
PROBLEM TO BE SOLVED: To clearly define relationship between cause and result for the genera tion of malfunction and burning accidents and external surges, by providing a fast-blow type fuse which blows when a surge current higher than the specified level flows for the specified period or longer to indicate impression of external surge. SOLUTION: This apparatus is provided with a surge protecting device Z, which when a surge higher than the specified protection level is impressed. This device Z operates when an external surface higher than the protection level is impressed and the surge current flows through a quick-blow type fuse F1. When such surge current flows in the level higher than the specified level for a period longer than the specified period, the quick flow type fuse F1 blows out, thereby checking impression of external surge. Moreover, when the quick blow type fuse F1 blows out, a bias voltage is generated on a bias resistor R1 of a surge impression display circuit and it is then impressed to the base of a transistor TR for lighting the display LED, and the display LED lights. Accordingly, the cause and effect relationship between the generation of malfunction, breakdown phenomenon and burning accident or the like and external surges can be clarified.
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