Abstract: A switched DC rotating electrical machine (100) comprising a stator (3), a rotor (2) and switching means (11a, 11b, 18a, 18b), an excitation winding (5) associated with one of the stator (3) or the rotor (2) having a pair of inputs, the excitation winding (5) being adapted to cause magnetization of a plurality of magnetic poles (4a -4l), the switching means (11a, 11b, 18a, 18b) being adapted to be associated with a DC voltage source (19) to switch the output thereof to the first and a second input of the excitation winding (5), the DC voltage source (19) providing a low voltage output (?V), an intermediate voltage output (0V) and a high voltage output (+V), wherein in use the intermediate voltage output is continuously connected to the first input of said excitation winding 19 and the second input is switched in a cyclic operation by the switching means between connection with the high voltage output (+V) and the low voltage output (?V).