Apparatus for determining and/or monitoring a process variable

An apparatus for determining and/or monitoring at least one process variable, comprising:

• at least one relay;
• at least one voltage source;
• at least one voltage increasing unit and
• a switch, wherein:
• said at least one voltage source provides a voltage which is smaller than a voltage for pull-in of said relay;
• said at least one voltage source is connected via said switch with said at least one relay;
• said at least one voltage increasing unit includes at least one electrical oscillatory circuit or at least one voltage storing unit;
• and
• said at least one relay, said at least one voltage source, and said at least one voltage increasing unit are embodied, matched to one another and connected with one another in such a manner that, when said switch is activated, such that said at least one voltage source and said at least one voltage increasing unit supply said at least one relay with voltage for pull-in, wherein said at least one voltage increasing unit produces a voltage additional to the voltage provided by said voltage source, thereby causing such an increase of the voltage applied to said at least one relay that the applied voltage corresponds at least to the pull-in voltage of said at least one relay and that, in the holding case after the pulling in of the relay, the voltage being supplied to the relay is smaller than the pull-in voltage.