The invention relates to a method for changing the active number of turns of a control winding (12) in an electric system (10). The control winding is coupled to an AC voltage network for a specified period duration T, is designed for a specified nominal current strength IN, and comprises a first and a second tap (121, 122). The control winding is switched from a first continuous current state, in which a load current flows from the first tap to a load discharge line (15) via a first main path and the second tap is separated from the load discharge line, to a second continuous current state, in which the load current flows from the second tap to the load discharge line via a second main path and the first tap is separated from the load discharge line, according to a specified switch sequence plan. The switch sequence plan specifies that starting from the first continuous current state, the first tap is connected or remains connected to the load discharge line via a first transition path, and the first main path is separated in a switch step a; in a switch step b, the second tap is connected to the load discharge line via a second transition path such that a circuit current iK flows through the transition paths on the basis of the stage voltage between the taps; in a switch step c, the first tap is separated from the load discharge line; and in a switch step d, the second tap is connected to the load discharge line via the second main path; wherein at at least one specified test time tT between switch steps a and c, a test is carried out to determine whether the first main path is separated; a current strength IL of the load current is ascertained; and the test time tT depends on the load current strength IL.