| 摘要 |
<p>A flame control circuit becomes a flame protection circuit when the whole circuit is also controlled with respect to correct operation. A final output signal 32 «presence of flame», is supplied only if a flame 6 is present and the circuit operates correctly. In any other case, in which parts of the circuit operate incorrectly, independently of the presence or absence of the flame, the output signal «absence of flame» is supplied. The circuit utilizes the rectifying effect of a flame on an alternating voltage applied to a measuring probe 2 in the flame, and the measuring direct voltage thus obtained, taken with an alternating voltage as reference and applied to correctly polarized phase detection circuits 28, 42 produces the said final output signal.</p> |
