Control system especially for forced draught gas fired burner

摘要

The control system includes an ionisation electrode (6) which is located in the flames of the burner. A microprocessor controller (15) is coupled to the electrode. The electrode is supplied by an AC current which is superimposed by an DC current corresponding to the ionisation current. The combined potentials form the input to a comparator (10) in which the DC offset potential determines the duration of the fixed amplitude comparator output voltage as a result of point-on-wave cut-off. The duration is independent of the AC amplitude and the resultant digital signal is opto-coupled (13) to the microprocessor controller with a D/A converter (16). The fuel inlet valve (3) and the fan speed control (5) is regulated.