A generator or motor apparatus having a stator formed of a plurality of pairs of parallel stator segments is provided The pairs of parallel segments are connected together to form a channel in which an annular rotor moves The annular rotor also comprises a plurality of detachable segments connected together to form an annular tram operable to move through said channel Each stator segment comprises a stator winding set and each rotor segment comprises a magnet dimensioned to fit between the parallel spaced apart stator segments The apparatus may include a support structure, the rotor segments being slidably coupled to the support structure and the stator segments being attached to the support structure The apparatus may be a rim generator, wind turbine generator or other electrical machine The stator winding set includes a stator winding, and may include other electrical or electronic components, including possibly a power factor capacitor, direct current filtering capacitor, supercapacitor, and one or more diodes The stator winding set may be encapsulated within the stator segment.