| 摘要 |
PURPOSE:To detect a fault of a thermistor of a temperature controlling device using a microprocessor by discriminating the fault of the thermistor based on the maximum and minimum temperatures which are set in advance and to be detected under a condition where the thermistor is installed. CONSTITUTION:A bridge circuit 1 converts a temperature change into a voltage and is composed of resistors 1a and 1b connected between a DC power source V and earth in series and a thermistor 1c for detecting temperature connected with the resistor 1a in parallel. A digital value corresponding to a detected temperature converted by an AD converter 2 is taken into a microprocessor 3. The output of the processor 3 controls the operation of apparatuses through a relay 5 and, at the same time, displays the fault of a thermistor through an LED7. The processor 3 discriminates the fault of the thermistor based on the maximum and minimum temperatures to be detected which are expected from the installed location of the thermistor. Therefore, abnormality can be detected surely and, as a result, the abnormal control of the apparatuses can be prevented. |
