| 摘要 |
PURPOSE:To improve the safety, reliability of measurement, and stability of a device by cutting off air temporarily in ignition and securing the ignition, and closing a gas valve immediately in case 9of the runaway of a computer and variation of a power supply. CONSTITUTION:The computer 16 sends an air cutoff signal to a pulse generator 27 during the ignition simultaneously with an ignition start signal and the air is cut off temporarily by the valve 25 to repeat igniting operation, thereby securing the ignition. When extinction occurs, a switch SW3 is placed at a side NC through a flame monitoring detector 8 and while an extinction signal is outputted from and AC/DC voltage level converter 22 to the computer 16, a relay driver 10 is operated through a flip-flop 20 to turn OFF a switch SW2 and close a valve 6, thereby stopping the entry of raw gas. Further, an input AC power source is so constituted as to prevent measurement in an unstable area by turning OFF the SW2 through a step-down transformer 28, an AC voltage variation detecting circuit 18, an AND gate 19, and the relay driver 10. |
