A synchronous machine mechanically connected with a load inertia is initialized at nominal speed. Subsequently a switch is closed and the induced voltages (by the permanent magnets) drive the stator currents through stator resistances and stator inductances out of the machine and through the external braking resistances. The internal and external losses are fed to a thermal capacitance, that increases the temperature. The amount of dissipated heat is equivalent to the kinetic energy of internal and external inertia.