Screened inductance sensors, especially sensors for level measurement

Abstract

In a screened inductance sensor having a drive winding, a sense winding, and a conductive screen for varying the induced voltage in the sense winding by reason of the eddy currents generated in the conductive screen in the presence of the drive field, a physical barrier is interposed between the region of the sensor in the windings are located and the region in which the screen is located. These regions are fully environmentally isolated from each other by the physical barrier. The construction is especially suited to screened inductance level gauges, in particular for fuel tanks, where the conductive screen is part of a float assembly in contact with the fuel, but the electrical windings are kept dry in a separate portion of the gauge. The sensor may make use of printed circuit windings, in particular, concentric turn windings without crossovers providing a similar electrical performance to equivalent distributed turn windings having crossovers, in which the turns are progressively displaced in the direction of relative screen and sense winding displacement.