Arrangement and method for protecting multiple voltage supply systems against voltage arc-over between different voltage planes and against pole reversal from the outside

An arrangement for protecting a multiple voltage supply system against voltage coupling between a high-voltage plane and a low voltage plane or against a pole reversal, with the high voltage plane including a high voltage battery, a controllable generator connected to the high voltage battery, and at least one high voltage load connected to the battery and the generator, and with the low-voltage plane including a low voltage battery and at least one load connected to the low voltage battery, said arrangement comprising

• a voltage-limiting unit connected, as to potential, between battery in the low-voltage plane and electrical ground to limit the voltage at said low voltage plane;
• a normally closed controllable battery disconnect switch connected in the high-voltage plane to disconnect the high voltage battery from the generator and the at least one load when opened;
• and
• control signal lines connecting control terminals of the voltage-limiting unit, the battery disconnect switch and the generator to each other;
• and wherein
• the voltage limiting unit includes circuit means for, upon detection of an undesirable voltage coupling from the high-voltage plane to the low-voltage plane, keeping the voltage in the low-voltage plane constant, and for transmitting a signal via the signal lines (a) to the battery disconnect switch to open the switch and separate the high-voltage plane from the high-voltage battery, and (b) to the control terminal of the generator and to adjust the output voltage of the generator down.