This PAS specifies the requirements of primary DC distribution systems and interconnected installations. The requirements of this PAS establish general principles for ? operations@ without degrading unit and human safety@ capable of a reduced environmental footprint@ ? existing and new power generating units@ new DC distribution concepts for electrical power@ energy storage and advanced control of a total power balance@ including semiconductor converters (AC to DC@ DC to DC and DC to AC power converters) and dynamic load controllers@ and ? relevant system studies and calculations demonstrating a protection philosophy as needed for necessary selectivity@ segregation methods and equipment. This PAS also gives guidelines for integration of energy sources of different nature and suitable ways to identify locations of such installations.