| 摘要 |
PURPOSE:To secure the safety of the devices to be controlled regardless of the occurrence of a fault, by providing an operation mode selecting part which drives a regulating valve in a safe direction by selecting the operation mode in response to various types of states of emergency and then controlling a switch control part. CONSTITUTION:A signal 6 given from a control gauge 4 and showing the target value is compared with a feedback signal 26a through a comparing part 27. A signal 27a corresponding to the deviation between the signal 26a and the signal 6 is delivered from the part 27. A switch control signal corresponding to the output signal 27a is produced from a switch controller 28. When a torque-over signal 33b is applied to an operation mode selecting part 31, the contents of an operation mode switch signal 31a is varied. Then controller 28 is locked to prevent the occurrence of a switch control signal 28a. Furthermore a disconnection of the cable which transmits the signal 6 to the part 27 is detected through the part 31. Then the controller 28 is controlled in accordance with the contents of the signal 31a. |
