| 摘要 |
PURPOSE:To continue the normal operation of a plant by evading the level rise of a drain tank, by forcibly opening a control valve by a signal generator in case of a transient state such as a sudden change in plant load. CONSTITUTION:A drain tank level is detected by a water-level transmitter 2 and then compared with a setpoint by a deviation operator 3 to input the extent of deviation to a PID operator 4. On the basis of a PID operation output, a water- level control valve is operated to hold the drain tank level constant. In case of a transient state, such as a sudden change in plant load, a switch 6 is changed over to a signal generator 5 side, and the signal generator 5 exercises advance control over the water-level control valve 5. |
