Dual/Redundant Self Check Ultraviolet Flame Sensor and Combustion Safeguard Control

Abstract

Two UV tubes are contained in one ultraviolet sensor to monitor one burner flame. Each UV tube is powered during a different time cycle to eliminate interference between the two UV tubes. This is made possible by two rectifier circuits being powered by two transformers that are 180° out of phase with each other. Self check is accomplished by the redundancy of two amplifiers providing output to two flame relays so that if one UV tube was to fail in the conducting mode, the combustion safeguard control will continue to safely monitor the flame by powering the fuel valve when the flame is present and removing power to the fuel valve when the flame goes out.

1 . In a burner fuel valve control, a control circuit consists of two UV tubes in one sensor housing, the rectifier circuits, two transformers 180° out of phase with each other, two amplifiers, two flame relays (output from amplifier), a safe start circuit and an output circuit controlling said burner fuel valve in response to combined circuit. 
     
     
         2 . The control circuit of  claim 1  wherein output circuit opens fuel valve in response to said presence of UV rays. 
     
     
         3 . The control circuit of  claim 1  wherein output circuit closes fuel valve in response to said absence of UV rays. 
     
     
         4 . The control circuit of  claim 1  wherein output circuit closes fuel valve in response to said absence of UV rays even if a UV tube fails in a conducting mode.