| 摘要 |
<p>The flame monitor has a change-over switch for testing and normal operation. The flame alerting switch (1) switches two parallel aggregates in and out with different delay times. Such aggregates might be the ignition unit (3) and the thermal time switch. The flame alerting switch consists of a triac switching a.c. but controlled by d.c. The triac's turn-on current is different for the positive and negative halfwaves. The delay time is produced by an RC circuit connected to the triac's gate and gives different delay times depending on the polarity of the half-wave. The monitor detects 'flame', 'no flame' and 'external light'.</p> |
