FLAME SENSING CIRCUIT USING AC POWER OF BOILER

摘要

PURPOSE: A flame sensing circuit using AC power of a boiler is provided to apply a flame sensing circuit to a flame sensing field easily by simplifying the circuit structure to detect generation of flames through comparison between pulse waveform of AC power and reference voltage. CONSTITUTION: A flame sensing circuit consists of: a flame sensing pulse generator(100) generating pulse voltage by AC power when flames are generated; a switching unit(200) switched on/off to generate pulse voltage; and a comparison unit(300) for comparing the pulse voltage with reference voltage. When AC power is fed to a flame sensing rod, the AC power is fed to a transistor(TR) to turn on the transistor. Pulse voltage is generated by the AC power through electric communication of the transistor. The pulse voltage is fed to an inverse terminal of a comparator(OP) of the comparison unit. The comparator compares distribution voltage with pulse voltage to generate high or low level of output voltage according to the result. The high or low level is inputted to an ADC(Analog to Digital Converter). The flame state is decided by the output signals from the ADC.