Subscriber line power distribution system

A power distribution system, comprising:

• at least three power supply units for feeding a plurality of subscriber line interface circuits, each adapted to be connected to a corresponding subscriber line;
• a switch unit adapted to connect current from the power supply units to the subscriber line interface circuits;
• and,
• a control unit adapted to:
• determine a loop voltage of the subscriber lines when engaged;
• set a different power supply voltage level for each of the at least three power supply units, wherein a highest power supply voltage level Vh is set to a value Vh=maxVab+Vas, wherein maxVab is a highest determined loop voltage and Vas is a predefined value for an anti saturation gap, and wherein the at least two power supply voltage levels below Vh are set by trying out combinations in predefined steps until a sum of the differences between the power supply voltage levels and the voltage levels needed to operate the corresponding subscriber lines is minimized;
• and,
• control the switch unit so that each one of the plurality of subscriber line interface circuits is fed from one of the at least three power supply units having a lowest power supply voltage level that is sufficiently high to operate the corresponding subscriber line.