The clamping assembly manufactured by the Končar – Power transformers factory consists of three different types of clamping elements to ensure the exertion of pressure upon the transformer core. One of these three types is a clamping element made of Polyglas® tape. This thesis deals with the experimental investigation of clamping elements made of Polyglas® tape in order to determine their mechanical properties. The qualitative and quantative analysis of the results of the experiment enable their behavior to be predicted and form a starting point for developing an empirical model for their sizing in various exploitation scenarios. Besides conducting the experiment on the existing clamping elements, an experiment on the proposed new clamping element was also carried out. It is proposed that the new clamping element design could replace one of the remaining two elements. The goal of the experiment was to determine the behavior of the new clamping element during installation, which could be used as a basis for evaluation of the effect that it exerts upon the transformer core yoke. Based on the conducted experiment, it is concluded that manufacturing processes have a significant impact on the final properties of the clamping element. The clamping element failure mechanism is described on an experimental rig and compared with the failure mechanism on the actual experimental transformer core. Furthermore, based on the experiment conducted on the proposed clamping element, it is concluded that there is no significant loss of the applied force within the element although further research is recommended.