A centrifuge for processing blood and blood components in a processing bag connected to at least one secondary bag comprises a rotor for spinning a processing bag and separating a content thereof in at least two components, and a squeezing member for exposing a processing bag to an external pressure and causing a transfer of a separated component from a processing bag into a secondary bag. Electrically powered devices, such as valves and photocells, are mounted on the rotor for controlling a transfer of fluid from a processing bag into a secondary bag. An electrical power supply system supplies the electrically powered devices with electrical power through the rotor.