| 摘要 |
PROBLEM TO BE SOLVED: To provide a service interruption detector capable of accurately recognizing whether service interruption occurs even when noise is overlapped on a commercial voltage. SOLUTION: The service interruption detector 10 comprises a control section 40 and a detecting section 30. The detecting section 30 detects a zero cross point at which the variation value by time transition of voltage crosses a predetermined detection range including voltage value 0 V. The control section 40 extends the detection range to a preset range when the detecting section 30 cannot detect a next zero cross point within a predetermined first time from the last detection of the zero cross point, and determines that the voltage to be supplied from a commercial source power supply is interrupted when the detecting section 30 cannot detect a next zero cross point within a predetermined second time from the last detection of the zero cross point based on the voltage range after the extension. COPYRIGHT: (C)2007,JPO&INPIT
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