Patent ID: 7400066

Claim:
A method of operating a power conversion apparatus including a plurality of parallel-connected uninterruptible power supplies (UPSs), the method comprising: determining a status of a bypass source of the plurality of parallel-connected UPSs based on a magnitude of a load share of a UPS of the plurality of UPSs when an aggregate loading of the plurality of parallel-connected UPSs meets a predetermined criterion, wherein determining a status of a bypass source of the plurality of parallel-connected UPSs based on a magnitude of a load share of a UPS of the plurality of UPSs when an aggregate loading of the plurality of parallel-connected UPSs meets a predetermined criterion comprises identifying failure of a bypass source of a UPS responsive to detecting that a magnitude of a load share of the UPS is less than a predetermined proportion of the aggregate loading; and determining a status of a bypass source of the plurality of parallel-connected UPSs based on a bypass source voltage when the loading of the plurality of parallel-connected UPSs fails to meet the predetermined criterion.