| 摘要 |
PURPOSE:To continue the operation with the conrol from a setting and operating device even if an operating output circuit of a control operating section is failed, by providing at least a circuit equal to the operating output circuit of the control operating section to the setting and operating device for duplicating a signal source driving a final control element. CONSTITUTION:A switch SW1 is ''opened'' and a switch SW2 is ''closed'' at the automatic operation and the result of operation from the control operating section is given to the final control element 3 through a diode D1, and resistors R1, R2 for MV(manipulated variable) feedback. If a failure takes place in the operating output circuit of the control operation section, the switch SW1 is closed automatically and the switch SW2 is ''opened'', then a signal is applied from an operating output circuit 252 to the fnal control element 3. Further, in driving the final control element from the control operation section, if malfunction of an operating output circuit 251 is detected as a result of checking of feedback informtion, the control is switched automatically to the setting and operating device. |
