| 摘要 |
<p>A protection circuit for an ionic flame monitor to insure that high voltage AC signals appearing across the flame electrodes and arising from sources other than a flame will not be effective to provide a false output indication of flame presence. The flame monitor is sensitive to AC signals above a certain frequency or above a certain voltage to indicate flame presence. Non-flame AC signals having voltages above or below the certain frequency, but above the certain voltage are prevented from indicating flame presence if their voltage is above a second certain level which is above that of most flame signal voltages.</p> |
