| 摘要 |
PROBLEM TO BE SOLVED: To obtain a detector which can detect whether the power-failure time is long or short by a method wherein the power-supply side and the detection side of an AC or DC object to be monitored are isolated and separated electrically. SOLUTION: A timer relay 2 is provided in such a way that an object to be monitored is operated by a power supply 1, that, while it is electrified a contact 2' is kept in a closed state, that, when the power failure of the power supply 1 is generated, the contact 2' is opened and that, when the power failure is restored, the contact 2' is closed so as to be delayed at least by the detection time. A turning-on element (a light emtting diode 12) is provided in such a way that it is turned on by a turning-on power supply while the contact 2' is closed. A light accumulating paint is provided in such a way that it is coated on the surface of a substrate 13, that it receives the light of the turning-on element, that it emits light while the element is turned on, that accumulated energy is discharged when the power failure of the power supply 1 is generated so as to turn off the turning-on element and that it emits light by an extinction characteristic. A comparison and detection circuit 21 is provided in such a way that, when the power failure of the power supply 1 is restored, the magnitude of the light receiving level of the light of the paint is compared with the magnitude of a set reference level and that whether the power failure time immediately before the power supply 1 is longer than a set time or not is detected. |
