| 摘要 |
PURPOSE:To keep off any sudden change in main steam pressure and the sudden change of a main steam control valve in time of anything unusual as well as to prevent a thermal stress in a turbine metal, by installing a control valve opening direction variation limit circuit in an output controller of a steam turbine. CONSTITUTION:A main steam pressure limit circuit 2 inputs a pressure setting value (a) and main steam pressure (b) and, in turn, outputs a control valve opening limit signal (f). An opening direction signal generator 6 inputs the signal (f) from a contact S1, while an opening direction variation limit signal (j) is inputted into a low value preferential circuit 7. Output of the circuit 7 and a speed deviation signal (e) out of an output control circuit 1 both are inputted into another low value preferential circuit 3, and the output (g) is transmitted to a valve control circuit 4. When the main steam pressure (b) is suddenly increased and thereby the signal (f) grows large, a signal (j) out of the opening direction signal generator 6 is selected at these low value preferential circuits, limiting the opeing of a main steam control valve. |
