| 摘要 |
<p>PURPOSE:To keep the temperature of piping equipment within a prescribed target value range by providing a mode switching device which changes control modes from a temperature controller to an auxiliary controller in case of a failure of normal control due to a fault of a temperature detector or the temperature controller. CONSTITUTION:The preheating temperature of piping 1 preheated by plural preheaters 2 is detected by a temperature detector 3, whose output is compared with a target value to send an on-off command from the temperature controller 5 to a contactor 4. For example, the breaking of wire occurs to the detector 3 of the controller 5, which then fails in normal control. In this case, the mode switching device 8 performs the switching of the output signal selection from the controller 5 to the auxiliary controller 7. Consequently, the controller 7 inputs the operation mode signal of facilities and outputs a means on-off pattern corresponding to the operation mode as an operation signal.</p> |
