Device for determining/monitoring of a predefined liquid level in a container

摘要

The arrangement has a mechanical vibration structure at the height of the predefined level to be monitored and a stack of piezoelectric elements. An electrical impedance (Z) connects a second signal line (241b) to a transmission signal line (5). A circuit produces a receiver signal from two electrical signals (E1,E2), corresponding to their difference. At least one piezoelectric element is a transmitter to which a transmission signal is applied by a transmission signal line, and which stimulates the vibration structure to vibrate. At least two further piezoelectric elements are receivers (24a,24b), each of which comprise two planar electrodes arranged parallel and perpendicular to the polarisation of the element. The piezoelectric elements detect the vibrations and convert them into electrical signals. The level is covered when the frequency of the signal is lower than a reference frequency.