Measuring transformer for filling state sensing elements

摘要

The transducer has measurement, compensation and counter electrodes connected to a measurement circuit with two test resistances in series in one arm of a measurement bridge. A second bridge arm contains the measurement resistance between the measurement and counter electrodes in series with the compensation resistance between the compensation and counter electrodes. A diagonal (26) between these arms (21,22) has a test switch (27) closed by a controller (13) outside defined test periods and opened during the test periods. An Independent claim is also included for a controller for a test switch.