A device for powering a single-phase electrical outlet if one or more phases fail

During the detection of the failure of the voltage on the first phase and the power supply of the appliance the power supply is on the basis of the instructions from the control unit (1) connected to the second phase; in case of the failure on the second phase the power supply of the appliance is connected to the available third phase. The device can have in preferable arrangement an accumulator (9) with the converter (10); in such case, after determining the outage on all available phases, the power supply of the appliance is connected to the output of the converter (10). The failure of the power supply in a given phase is detected by a single sensor (3) which is placed on the supply branch on the side of the plug (4) behind the point of switching of the phases. The device can have three switches (21, 22, 23) with two input poles ordered one after another in a cascade, whereby the output from the first switch (21) is connected to the first input pole (22a) of the second switch (22); the output from the second switch (22) is connected to the the first input pole (23a) of the third switch (23); and the output from the third switch (23) is connected to the plug (4).