| 摘要 |
PURPOSE:To reduce variation in the flow rate of air at the time of changing the mode of operation from variable-speed operation to operation using a commercial back-up circuit, by operating an air-flow control valve immediately in response to the output signal of a pattern generator. CONSTITUTION:On the basis of the output of a main steam flow detecting circuit 18, a pattern generator 19 produces a reference value of the valve opening for determining the flow rate of main steam, i.e., the flow rate of air based on the fuel supply rate and the reference value is applied to a means 13 for driving an air-flow control valve 12 via a contact 20b. Then, forced restriction of the opening of the air-flow control valve 12 is started. Further, when it is detected by an equality detecting circuit 20 that the reference value produced by the pattern generator 19 is equal to a feedback signal produced by an air-flow detector 16, the control mode is shifted to the normal air-flow control by controlling the opening of an air-flow control valve 6. At the time of shifting the control mode, a breaker 11a of a commercial power source back-up circuit 11 is opened and a breaker 11c is closed, thereby connecting a voltage reducing reactor 11b in the circuit. Thus, a motor 9 supplied with current from the circuit 11 can reduce the speed of rotation after shifting of the control mode by way of reduced- voltage starting. |
