The overhead power system supplying electricity to a train consists of the pantograph current collector and the overhead line equipment. Many of the parameters describing the dynamic characteristics of the pantograph vary during the lifetime due to wear, mounting conditions, weather etc. When evaluating the dynamic performance of the pantograph it is important to consider a realistic range of variation in key parameters. To study this problem a three-dimensional pantograph model has been developed. It is based on the Schunk WBL88/X2 pantograph used for the Swedish high-speed train X2. The performance of the model of the overhead power system is analysed using a multibody dynamics program. In this work, the influence on the dynamic behaviour of the pantograph, due to changes of key parameters in the head suspension, is investigated using numerical simulations and the methodology of factorial design. The ranges of variation in parameter values are determined from measurements on pantographs subjected to different wear situations.