A method in a control unit for closing a contactor device. The control unit is configured to enable the movement between the closed and opened position by energizing a coil of an electromagnetic circuit. The method includes applying a voltage over the coil; determining, during a first period of time, current through the coil and voltage over the coil and estimating based thereon model parameters for a model predicting the behavior of the current through the coil if the contactor device were to stay in an open position, and measuring, after the ending of the first period of time, current through the coil and determining a difference between, on the one hand the measured current and, on the other hand a predicted current of the model, and repeating the measuring and determining until a state change from open position to closed position is detected by the difference in current.