| 摘要 |
An automatic control system in which electrically operated fuel and air supply and ignition means are energized at supply line voltage through a circuit controlled by a thermal time switch and a solid state switch; the system further including gating means for the solid state switch under control of a small sensitive electromagnetic relay having two windings parallel connected in a low voltage thermostat circuit. Closure of the small relay to effect conduction of the solid state switch requires energization of one or both of its windings but requires only the energization of the other of the windings to hold it closed, current flow through the other or hold-in winding being rectified and capacitance filtered with sufficient capacitance to retain hold-in energization through momentary interruptions of the thermostat circuit; the system further including an electrical resistance heater series connected with the one relay winding and operative when energized for a short predetermined period of time to heat and open the thermal time switch, and flame responsive switching means operative to instantly de-energize the resistance heater and the one series connected relay winding when flame appears at the burner.
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