Patent ID: 7459803

Claim:
An isolated-parallel UPS configuration comprising: two diesel UPS systems, operating at either low voltage, medium voltage or a combination or low and medium voltage, adapted to supply power from a utility power source to corresponding dedicated essential and critical loads, the diesel UPS systems adapted to operate as independent systems, each diesel UPS system including an inductive reactor (choke) adapted to condition utility power for use in critical loads, a diesel engine adapted to supply a long-duration alternate source of power for both critical and essential loads upon interruption of the utility power source, and an energy storage mechanism coupled to a motor-generator and adapted to supply a short-duration alternate source of uninterrupted power to its critical load upon the onset of power interruption for a period of time required for the diesel engine-generator to start and take over support of the critical loads; a system switchboard for each diesel UPS system adapted to accommodate transferring essential and critical loads between utility power and diesel engine power; an output bus for each diesel UPS system adapted to accommodate the attachment of the inductive reactor and motor-generator to critical loads and to facilitate the transfer of critical load to and from utility, diesel engine and short-duration power sources; and at least one IP choke adapted to connect to the output bus of one of the Diesel UPS Systems adapted to allow power to flow from one output bus to the other output bus and to limit fault current between the diesel UPS systems, thereby isolating each diesel UPS system from faults on the other diesel UPS system.