Abstract: Apparatus for determining and/or monitoring at least one limit value of a process variable of a medium in a container, comprising at least one sensor unit for registering a measured value dependent on the process variable and at least one electronics unit for producing a measurement signal dependent on the process variable. The invention is distinguished by features including that the apparatus is embodied to draw energy via a voltage output and a digital input of a recorder apparatus or a process control system.

Abstract: A circuit arrangement for the protection of at least one component of a two wire electrical current loop, which is connected in series with a burden to an AC/DC electrical current source. The two wire electrical current loop has a rectifier a clock signal producer and a switch. The rectifier forms a DC circuit, wherein the component is connected in the DC circuit and wherein the clock signal producer outputs a clock signal to the switch for clocking the DC circuit. The circuit arrangement has a diode, wherein the conduction direction of the diode points from the anode of the diode to the cathode of the diode. The cathode of the diode is connected to the DC circuit, and the anode of the diode is supplied with a periodic or constant voltage from a first voltage source, and the voltage is at least periodically greater than a predetermined threshold value.

Abstract: The invention relates to a circuit arrangement for the protection of at least one component 3 of a two wire electrical current loop, which is connected in series with a burden 1 to an AC/DC electrical current source 16, wherein the two wire electrical current loop has a rectifier 2, a clock signal producer 9 and a switch 3, wherein the rectifier 2 forms a DC circuit 12, wherein the switch 3 is connected in the DC circuit 12 and wherein the clock signal producer 9 outputs a clock signal T to the switch 3 for clocking the DC circuit 12, characterized in that the circuit arrangement has a diode 4, wherein the conduction direction of the diode 4 points from the anode KN of the diode 4 to the cathode KA of the diode 4, the cathode KA of the diode 4 is connected to the DC circuit 12, the anode KN of the diode 4 is supplied with a periodic or constant voltage from a first voltage source 6a, and the voltage is at least periodically greater than a predetermined threshold value S.

Abstract: A measuring device, comprising: an input circuit having a supply line and a return line. Energy supply occurs over a line-pair. Input voltage is applied to the measuring device via the line pair. A series regulator for controlling an electrical current flowing via the line-pair, a shunt regulator installed in a parallel branch, and an apparatus for controlling a voltage drop across the series regulator are provided.

Abstract: Apparatus for determining and/or monitoring at least one limit value of a process variable of a medium in a container, comprising at least one sensor unit for registering a measured value dependent on the process variable and at least one electronics unit for producing a measurement signal dependent on the process variable. The invention is distinguished by features including that the apparatus is embodied to draw energy via a voltage output and a digital input of a recorder apparatus or a process control system.

Abstract: 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.