Currently, induction machines with a gear-box are used in most small hydropower plants. The unfavorable efficiency of induction machines during partial load conditions has proved to be a disadvantage during low water periods. The newly developed high-pole permanent magnet synchronous generator is very suitable for these operational conditions and does not require a gear-box or slip rings and brushes. By using a frequency converter the rotational speed of the machine can be varied over a wide range, which results in overall efficiency gains.