FIELD: power supplies. SUBSTANCE: device has at least one buffer battery such as storage cell charged through power unit and control unit. The latter turns on buffer battery when rms value of dc voltage is lower than desired minimum, sets desired buffering time interval tm, and turns off buffer battery upon expiration of this time. Recovery of power-unit output dc voltage can be effectively identified without great expenses. Users are still supplied with power both in spite of failure of input supply voltage and power unit proper as output dc voltage of the latter is under control. Device may be connected, in addition, bypassing the power unit without intervention in its design. In case of dc voltage dip across power unit output battery is automatically turned on to function as backup supply in response to voltage drop across user's equipment below minimal value. In this way, device provides for stepless transfer or maintenance of dc voltage across power unit output. EFFECT: improved reliability of dc voltage buffering. 6 cl, 6 dwg
