Up to now Kragten Design has developed thirteen electricity generating windmills with rotor diameters in between 1.2 and 4.6 metre. All these windmills are provided with 4-pole PM-generators which are made of standard asynchronous motors. The normal short-circuit armature is replaced by a permanent magnet armature for which neodymium magnets are used. All VIRYA windmills are used for 24 or 48 V battery charging and the 3-phase current coming out of the generator has there fore to be rectified.