Parker-Hannifin Corporation
CAPACITIVE FUEL GAGING SYSTEM WITH RESISTIVE ELEMENTS

Abstract:

A fuel gaging system, such as may be used in determining an amount of fuel in an aircraft fuel system, includes a capacitance probe and a capacitance measurement circuit component including high resistance elements. The capacitance measurement circuit component includes a first excitation generator, an excitation wire connected between the first excitation generator and the capacitance probe, and a signal wire connected to the capacitance probe with the capacitance probe being connected between the excitation wire and the signal wire, wherein the first excitation generator generates an input signal applied to the excitation wire and an output signal is read from the signal wire to determine a capacitance at the capacitance probe. The system further includes a wire resistance measurement circuit component configured to isolate a contamination resistance to account for variations in wire resistance of the system wires in determining the capacitance at the capacitance probe; and a contamination compensation circuit component configured to compensate for fuel contamination in determining the capacitance at the capacitance probe by compensating for a slope error in the output signal.