20130271156 | Measuring Device - A measuring device for measuring a process variable, comprising: an input circuit having a supply line and a return line, connectable to a superordinated unit. Energy supply of the measuring device and signal transmission, between the measuring device and a superordinated unit occurs over a line-pair. Input voltage is applied to the measuring device via the line pair. A series regulator installed in the supply line for controlling an electrical current flowing via the line-pair, a shunt regulator connected after the series regulator and installed in a parallel branch, and an apparatus for controlling a voltage drop across the series regulator are provided. The apparatus sets the voltage drop across the series regulator as a function of the applied input voltage, which is greater than a predetermined minimum input voltage, to a value predetermined by a characteristic curve for the particular input voltage and lying above a minimum value required for operation of the series regulator. A measuring sensor connected to the input circuit and supplied with energy via the input circuit for determining the process variable and for producing a measurement signal representing the process variable. | 10-17-2013 |