Level switch and method for detecting the fill level of a medium in a container

Abstract

A level switch detects the fill level of a medium in a container and transmits a switch signal corresponding to the detected level. The level switch incorporates a signal generator for generating an electromagnetic signal, a measuring circuit, and a reference circuit into which the electromagnetic signal can be fed. The measuring circuit is so configured and positioned that the signal fed into the measuring circuit changes as a function of whether or not the measuring circuit is surrounded by the medium, while the reference circuit is so configured and positioned that the signal fed into the reference circuit remains unaffected by the fill level of the medium. A tap at a specific point on the measuring circuit collects the measuring voltage, a tap at a specific point on the reference circuit collects a reference voltage, and a voltage comparator compares the measuring voltage with the reference voltage and emits a comparison-derived switch signal. This permits the dependable detection of a specific level of the medium in the container while essentially eliminating errors due to changes in extraneous parameters such as temperature fluctuations. A method for detecting the fill level of a medium in a container employing the switch is also disclosed.