NO-BREAK POWER SUPPLY SYSTEM Russian patent published in 2003 - IPC

FIELD: electrical engineering; power supply to important users. SUBSTANCE: system has adjustable and nonadjustable ac power supplies, input signal switch, analog-to-digital converter, microprocessor controller, and digital-to-analog converter. One load lead is connected to common neutral terminal of power supplies and its other lead, to phase bus of each power supply through making contacts of magnetic line contactors and through primary windings of equalizing transformers. Adjustable power supply incorporates output voltage regulator, comparison gate, voltage feedback sensor, adjustable reference-voltage supply, built-in protective unit, and contactor. Nonadjustable power supply has built-in protective unit and contactor. System also has four sensors; input of one of them is connected to output of adjustable power supply, that of second one, to load leads, input of third sensor, to common neutral terminal and through equalizing instrument transformers, to phase bus of adjustable ac power supply. Input of fourth sensor is connected to output of nonadjustable ac power supply. Under normal conditions voltages across outputs of adjustable and nonadjustable power supplies equal zero. This information arrives at input of switch whose output is connected to analog-to-digital converter and output of the latter is connected to microprocessor controller. With voltages across outputs of both power supplies being equal, signal for turning on control switches of power supplies arrives at outputs of the latter from microprocessor controller output. In case of change in voltage across nonadjustable power supply this information arriving at microprocessor controller is compared in the latter with reference voltage with the result that error voltage is built up which acts on output voltage of adjustable power supply through analog-to-digital converter to step it up or down until load voltage is brought to rated value. Joint action of multiprocessor controller and analog-to-digital converter, as well as their connections with ac power supplies provides for conversion of voltage values into digital codes, their storage, comparison, subtraction according to predetermined algorithm thereby preventing abrupt voltage variations at user s and tendency to raise this voltage. EFFECT: enhanced reliability. 1 cl, 3 dwg