Design and tests of generators for micro hydro plants

The paper presents the design, parameters and selected results of tests conducted for two generators designed to work with a small water turbine. Both generators use the same stator. The first generator has the rotor in the form of a steel pipe with segment magnets glued, on it. In the second generator magnets are placed inside the rotor that is composed of plates. The generator stator has 36 slots holding a three-phase eight-pole winding. In order to minimize cogging torque the skew of three magnets bonded on the surface is applied in the first rotor. The second rotor is divided into 6 segments twisted with respect to one another by 2 degrees. The housings and shield bearings of a standard three-phase motor are used to construct the generators. The paper presents selected test results including the influence of output voltages upon rotational speeds, the influence of the output voltages upon the load current, the measurements of cogging torque and the results of generator warm-up. The turbine generator set designed for micro hydro plant is presented.