Vehicle electrical system having a high-voltage branch, a low-voltage branch, and low-voltage-side insulation fault detection

A vehicle electrical system for detecting insulation faults, the vehicle electrical system comprises:

• a high-voltage branch comprising a sensor;
• insulation comprising insulation-bridging components and/or insulation material;
• a first low-voltage branch galvanically isolated from the high-voltage branch by the insulation, the first low-voltage branch includes:
• a plurality of low-voltage lines extending from the high-voltage branch into the low-voltage branch, the plurality of low-voltage lines functionally distinct and includes:
• a signal line for transmitting signals from the sensor,
• an actuation or data line for interfacing with a data source or sink of the high-voltage branch, and
• a low-voltage supply line, the plurality of low voltage lines operate with signal levels between 0 volt to 18 volts;
• and
• a voltmeter having an input for receiving the plurality of low-voltage lines, the voltmeter detects when an absolute voltage value of the at least one of the plurality of low-voltage lines, with respect to a ground potential of the vehicle electrical system, lies above a voltage limit, the voltage limit defines an absolute voltage value greater than an absolute value of a maximum signal voltage of the low-voltage line, which the low-voltage line has during fault-free operation,
• wherein the plurality of low-voltage lines are led out from the high-voltage branch and are monitored by the voltmeter on the first low-voltage branch;
• and
• wherein the plurality of low-voltage lines are respectively connected via a series resistor to the input of the voltmeter and the input is connected via a shunt resistor to the ground potential of the vehicle electrical system.