Abstract: A Direct Current (DC) Isolated-Parallel (Iso-Parallel or IP) Uninterruptible Power Supply (UPS) system and method for converting incoming AC power to DC power using several modules which are paralleled at their outputs yet fault isolated from each other. The DCIP UPS has two or more modules connected to a common IP Bus which operates at AC voltage and is disposed between a facility electrical distribution system and the facility's critical electrical loads which operate at DC voltage. The electrical distribution system receives power from a local utility, or from a standby power source when utility power is unavailable, and delivers AC power to the DCIP UPS input. The DCIP UPS converts the power to DC and delivers it to critical electrical loads associated with computer equipment or other devices using DC power.

Abstract: An Iso-Parallel UPS system may combine the system redundancy, isolation and fault-limiting properties of isolated-redundant systems, with the ability to spread system load evenly across all modules like paralleled systems. This system may have the following features: (1) the critical load can be divided into two or more portions, and each portion may be individually fault tolerant, i.e., any electrical fault on a critical load will affect only the load in that portion—other portions of the critical load can remain connected and operating; (2) the critical load can be shared among all modules within the configuration, and all modules may be equally loaded, or nearly equally loaded—there is no designated redundant unit; and (3) any module can be taken out for maintenance without impacting the critical load.