| 摘要 |
PURPOSE:To prevent the stop of the power supply of an apparatus due to a power supply control means even when only the contact of one temp. detection means is opened by providing a plurality of temp. detection means whose contacts are opened at prescribed temp. or higher at respective detection points. CONSTITUTION:Thermostats 3 are mounted at respective detection points by two and one thermostats 3 are connected so as to connect the respective detection points in series and, when the temp. in electronic machinery is raised by the fault of cooling fans 2 and the contacts of the thermostats 3 are opened, a power supply control circuit 4 confirms this state to stop a power supply. Now, when two thermostats 3 are normal, the contacts of both of two thermostats are in a closed state in such a case that the vicinal temp. of a housing 1 is prescribed temp. or lower but, when the contact of one thermostat is opened by fault, if other thermostats are normal, the power supply control circuit 4 does not confirm that the contact is opened and does not stop the power supply of the apparatus. |
