| 摘要 |
PROBLEM TO BE SOLVED: To enable secure and timely maintenance in accordance with the lifetime of a surge resistant element, thereby improving the reliability of the surge resistant element and an electronic apparatus using this element. SOLUTION: When a surge is applied to a varistor 12, the surge current is detected by a current sensor 13 and a current detecting part 14, and the number of application of the surge is counted. A lifetime determination part 15 compares the detection value of the surge current and the count value of the number of the surge application with impulse lifetime property using the maximum value of a fixedly set protocol wave tail length, and determines whether or not the varistor 12 has reached its lifetime based on the comparison result. When the varistor 12 has reached its lifetime, a determination result informing part 16 displays to that effect, thereby notifying a maintenance person or the like of that. COPYRIGHT: (C)2004,JPO&NCIPI
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