Apparatus for controlling the power of an AC voltage supplying an electrical consumer by phase control and method for reducing harmonics

Apparatus for controlling the power of an AC voltage supplying an electrical consumer by phase control and for reducing mainly the third harmonic caused by said phase control, comprising a first switching element (TRIAC) connected in series with said consumer and driven at a first firing angle into a conducting state by a control device for performing a phase control of said consumer during a given half cycle of the AC supply voltage, characterized in that a second switching element and a resistor element are provided, both being electrically connected in series to form a series connection, said series connection is provided parallel to the first switching element, said control device being adapted to drive the second switching element at a second firing angle into a conducting state at a first point in time (t1) during said given half cycle that is shortly before a second point in time (t2) when the first switching element is driven into the conducting state.