| 摘要 |
<p>A burner control apparatus includes a timing circuit for providing two successive timing intervals of precise duration, one being a preignition timing interval and the other being an ignition timing interval. The timing circuit includes a capacitor the charging rate of which determines one of the timing intervals and the discharge rate of which determines the other timing interval. In response to a call for burner operation a blower is energized to purge the burner of potentially explosive gases during the pre-ignition timing interval. When the pre-ignition interval comes to an end relays are energized to energize a pilot fuel control and an ignition control. If a flame is sensed during the ignition interval a further relay is energized closing the ignition control and switching over from pilot to main fuel control. If no flame is sensed during this interval a lockout actuator shuts down the entire burner and energizes an alarm. If after establishment of normal burner operation the flame goes out,the cycle of two successive timing intervals is repeated.</p> |
