Abstract: A craft, such as an aircraft, landcraft, watercraft, space craft, or the like, is provided with a power transfer system which ensures an uninterrupted supply of electrical power to on board electrical equipment during normal switching from one power supply to another i.e., switching which is not due to system failure, which switching may be initiated either manually by the pilot, or automatically by the system. The power transfer system can be used with separate DC power sources, and includes a split bus assembly which ensures a continuous electrical equipment supply from a first operating power source until after a second different power source has been energized and begun to supply operating power to the electrical equipment in question. Once the second power supply is brought on line, the first power supply can be shut down. The system can be used when switching between different on board power supplies or when switching between on board and external power supplies.