Monitoring device for a high-voltage onboard electrical system, and method for operating a monitoring device

A monitoring device for a high-voltage onboard electrical system of an electrically operable vehicle,

• the monitoring device comprising:
• a current sensor configured to:
• determine a sum of:
• an electric current of an electrically positive charge line, and an electric current of an electrically negative charge line,
• wherein the electrically positive charge line is configured to couple a high-voltage energy storage device of the onboard electrical system to a charging connection that is in turn connected to a positive electric voltage of a charging device so as to charge the high-voltage energy storage device, and
• wherein the electrically negative charge line is configured to couple the high-voltage energy storage device to the charging connection that is in turn connected to a negative electric voltage of the charging device so as to charge the high-voltage energy storage device;
• a control unit configured to:
• detect a fault based on the determined sum, and
• separate the electrically positive charge line and the electrically negative charge line from the high-voltage onboard electrical system upon detection of the fault.