ARRANGEMENT FOR UNINTERRUPTABLE POWER SUPPLY TO A LOAD FROM TWO OR MORE A.C. POWER SOURCES

摘要

The present invention relates to an arrangement for uninterruptable power supply to a load, for example a data processing equipment. To the load at least two A.C. power supplies are connected each via a pair of antiparallel connected controlled rectifiers, for example thyristors. One rectifier in each pair is brought to its conductive state simultaneously as the corresponding rectifier in all the other pairs and remains in this state as long as the voltage across and the current through the load have the same polarity during one half-period. During the next half-period the other rectifier in all the pairs is brought to its conductive state. Upon failure in one of the power supplies, for example the mains, both the rectifiers in the pair connected to this supply will become blocked and power to the load will be delivered from the other power supply or supplies via the other controlled rectifier pairs.