| 摘要 |
PURPOSE:To detect speedily and accurately an anomalous such as a short-circuit and disconnection if the anomalous occurs and to improve the reliability of a temperature controller by converting the resistance variation of a temperature sensor into voltage variation with a resistance-voltage converting circuit, comparing the output voltage with the 1st and the 2nd predetermined set voltages, and displaying the result on the 1st or the 2nd display devices. CONSTITUTION:If a disconnection accident occurs to a temperature sensing element Th, an output voltage V0 is developed at the output terminal (e) of the resistance-voltage converting circuit 2 and higher than a disconnection detection voltage V1. Therefore, the 1st digital comparator OD1 turns on to apply a control voltage to a relay RY1 and a light emitting diode LED1, which turns on to cut off the current of a heater H. The disconnection voltage V0 is higher than a short-circuit detection voltage V2, so the 2nd digital comparator OD2 does not operate. If a short-circuit accident occurs to the Th, an output voltage Vs is developed at the output terminal (e) and lower than the short-circuit detection voltage V2. Therefore, the 2nd digital comparator OD2 turns on to light a light emitting diode LED2, cutting off the current of the heater H. |
