Power supply system, and uninterruptible power supply including a power supply system

An uninterruptible power supply comprising a power supply system, the power supply system, comprising:

• an AC input, an AC output, and a DC input;
• a DC intermediate circuit/a DC link;
• a first converter connected, via a first bistable switching circuit, between the AC input and the DC intermediate circuit;
• a second converter connected, via a second bistable switching circuit, between the DC intermediate circuit and the AC output;
• a third converter connected, via a third bistable switching circuit, between the DC input and the DC intermediate circuit;
• a bypass circuit connected, via a bypass bistable switching circuit, between the AC input and the AC output and configured to provide a bypassing path from the AC input to the AC output;
• and
• a control unit configured to control an operation mode out of a plurality of operation modes of the power supply system, wherein in each operation mode of the plurality of operation modes, at least one of the bistable switching circuits is in a galvanically isolated state, wherein the operation mode comprises at least:
• a bypass circuit connection mode in which the bypass bistable switching circuit is in an electrically conductive state;
• and
• a bypass circuit isolation mode in which the bypass bistable switching circuit is in the galvanically isolated state, wherein the control unit is further configured to detect a system state and to select the operation mode out of the plurality of operation modes according to the detected system state, the system state and the selected operation mode including a bypass circuit defect system state, in which state the bypass circuit location isolation mode is selected, wherein the bypass bistable switching circuit is operated to be in the galvanically isolated state.