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US 8,875,557 B2Granted
Circuit diagnostics from flame sensing AC component
AssigneeHoneywell International Inc.
InventorsBrent Chian, Timothy J. Nordberg
Life of this patent
Estimating the term…
Abstract
A diagnostic flame sensing circuit having less filtration so that an AC component of a flame sensing input is available for circuit diagnostics. Synchronized data sampling may used to detect the peak to peak magnitude of the residual AC component. A comparison of the magnitude of the component relative to a magnitude of the component during normal operation of the circuit may be used to check the condition of nearly all of the elements in the circuit.
Claims11
A diagnostic flame sensing circuit comprising:
- a chopper;
- a high voltage DC source connected to a first terminal of the chopper;
- and
- a filter connected to a second terminal of the chopper;
- and
- wherein:
- a first output of the filter is provided to a flame sensor;
- a second output of the filter comprises diagnostic information;
- when the flame sensing circuit is activated, an analysis of the second output of the filter reveals a condition of one or more circuit components of the flame sensing circuit;
- and
- the revealed condition of one or more circuit components of the flame sensing circuit includes one or more of:
- a resistor having leakage;
- a resistor being open;
- a capacitor being smaller than normal;
- a resistor to resistor ratio being incorrect;
- a capacitor being shorted;
- a frequency of a pulse width modulator being too low;
- a capacitor having leakage;
- the sensing timing of an analog-to-digital converter being out of sync with an output signal of the chopper;
- the chopper having stopped;
- a DC-DC voltage converter component not operating;
- a frequency of a pulse width modulator being too low;
- a capacitor being open;
- the output of the second filter containing too much noise;
- and
- a microcontroller having lost control over the chopper.
23 more elements
Dependencies are inferred from the claim text.