Abstract: A structure for an a.c. electrical machine and method of transducing power between two different systems. The machine comprises two electrically balanced transformers which are generally, but not exclusively, three phase. Initially the transformers are in balance and no currents flow in the secondary windings of the transformers. An electrical or mechanical imbalance is introduced between the transformers causing current to circulate in the secondary windings. The secondary windings in one embodiment are provided on a rotor in which case the currents induced in the secondary windings cause a torque to be exerted on the rotor. It is also possible to arrange the machine as a transformer or alternator.