Power supply apparatus is disclosed which can be configured as a power line filter or an uninterruptible power supply having a battery test on load capability. It comprises an input reversible rectifier connectable between an AC supply and a high voltage internal DC bus, a second reversible rectifier...http://www.google.fr/patents/US5126585?utm_source=gb-gplus-shareBrevet US5126585 - Uninterruptible power supplies
