A permanent magnet comprises a primary winding, a secondary winding, a permanent magnet, an output terminal for connection to an external load, and a switching mechanism with two modes. In a first mode of the switching mechanism, the primary winding is connected between neutral and the output terminal, and the varying magnetic flux from the permanent magnet induces a nonzero voltage at the output terminal. In the second mode, the secondary winding provides a return path to neutral for the primary winding, thereby providing negligible voltage and current at the output terminal and substantially canceling change in magnetic flux from the permanent magnet.