PURPOSE: To clearly understand the flow of electricity through vision by likening a bundle of optical fibers to an electric wire and making a model as a stator winding of a three-phase induction motor, and generating a variation of currents of each phase of three phases in separate colors.

CONSTITUTION: A winding is formed by bundling optical fibers 2 to a three- phase winding being a stator winding of a three-phase induction motor, it is wound round to a model of a stator iron core 1 of the three-phase induction motor, and its connecting method is a three-phase star connection connected by a connecting method having no neutral point coupling. In such a state, in each phase of a three-phase AC current, light radiated from a lamp 4 is made incident on an end face of the optical fiber 2 through a color plate 3, and the optical fiber 2 itself shines, by which the three-phase AC current is made simulatedly, and a timewise variation of a three-phase AC and a rotating magnetic field is generated in separate colors. In such a way, the three-phase AC and the rotating magnetic field are understood through vision.