IT system with voltage-compensated insulation monitor

Abstract

The invention relates to an IT system (1) for a motor vehicle, comprising: - a power supply unit (2) with two poles (P1, P2), - a ground-potential-carrying component (3), - an insulation monitor (5) for monitoring an insulation state of the IT system (5), which is voltage-compensated and comprises: - an energy storage unit (6), - a pre-charging circuit (9) for charging the energy storage unit (6) to a terminal voltage (UC1) which corresponds to a pole-component voltage (UG+) between one of the poles (P1) of the power supply unit (2) and the component (3), - a resistance measuring device (8) for detecting an insulation resistance (RISO_E) between the power supply unit (2) and the component (3), - a switching device (7) which, in a pre-charging switching state, is designed to connect the energy storage unit (6) to the pre-charging circuit (9) by forming a pre-charging circuit (KV).and which, in a measuring switching state, is designed to connect the energy storage device (6) in anti-series with the pole (P1) by compensating the pole-component voltage (UG1) with the terminal voltage (UC+) and to connect the anti-series connection, the insulation resistance (RISO_E), the power supply device (2), the component (3) and the resistance measuring device (8) by forming a measuring circuit (KM).

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