SYSTEM OF UNINTERRUPTED POWER SUPPLY Russian patent published in 1995 - IPC

FIELD: electrical engineering. SUBSTANCE: phase terminals 2 of controlled and uncontrolled A.C. power supply sources are connected through windings of equalizing transformers 8 and 9 to A.C. user 3. Controlled A.C. power supply source 1 includes controlled source 25 of reference voltage which input is coupled to output of voltage comparator 23 across output of user 3 with nominal voltage. Novelty of system lies in fitting of it with unit composed of two-threshold comparators 44 and 45, sources 48 and 49 of bias voltage and controlled keys 46 and 47 which make it possible to change voltage of controlled source 1 so that with switching on of A.C. sources 1 and 2 for parallel operation deviation of voltage across user 3 does not exceed maximum permissible norm. EFFECT: enhanced efficiency and reliability of system of uninterrupted power supply by expansion of range of parallel operation of controlled and uncontrolled A C power supply sources. 1 dwg