A DC power supply apparatus and method of supplying DC power for mission critical applications utilizes multiple power circuits in one unit, the power circuits being optimizable for efficiency as the load increases or decreases. The individual power supplies may use a multiphase topology within the power circuits, with logic phase shifts between multiphase, and two types of power management circuits arranged in parallel, or an equivalent controller, for implementing: (a) a variable linear or variable exponential precision droop algorithm, and (b) a “virtual bus” or current averaging/active current sharing circuit, the current sharing being provided by a low bandwidth communications link between droop controllers in each of the power circuits. In addition, the droop/paralleling circuitry and/or programmed components may be arranged to implement two types of arc detection and suppression, including: (a) unequal positive and negative current in each power circuit to shut down the output power, and (b) monitoring output current for an arc “signature” to protect against arcs between positive and negative.