<p>The device has parallely operated power supply modules (10, 10') utilized in common or separate switch cabinets (1) or rack. The modules have an inverter branch (40) for uninterruptible electrical power supply of a load. The power supply modules have a bypass (30) connected with a load branch (80) parallel to the inverter branch, where the bypass is separated from the load branch during error free functioning of the inverter branch and is connected with the load branch during failure of the inverter branch for the maintenance of the power supply automatically by a control circuit (20).</p>
