Device and method for detecting a polarity reversal on a low voltage side of a DC voltage transformer in a dual-voltage vehicle electrical system

A device for detecting a polarity reversal on a low voltage side of a DC voltage transformer in a dual-voltage vehicle electrical system, comprising:

• a controllable switching element for selectively enabling and interrupting a current flow in a connecting line on the low voltage side of the DC voltage transformer;
• a current sensor system for detecting the current in the connecting line on the low voltage side of the DC voltage transformer;
• and
• an evaluation unit for evaluating the direction of the detected current and for detecting a polarity reversal if the direction of the detected current deviates from an expected current direction;
• wherein, in a standby mode of the DC voltage transformer, the switching element is closed by the control unit at regular time intervals.