Nonlinear mathematical model of hysteresis is suggested for a specific device meant for suppression (energy dissipation and vibration unbalancing) of bundle conductors galloping. The approach is complex one including experimental part connected with realization of typical measurements and mathematical part connected with data processing. The work results are both systematized experimental data and mathematical algorithm for modeling of arbitrary angular motion of a real damping unit. The hysteresis curves are constructed in the space of virtual deformation diagrams {M,f} between limit cycle boundaries; M is a torsional moment of a damping unit, f is a rotation angle corresponding to this moment. A value of M is found taking into consideration the prehistory of deformation process. The results of this research can be helpful for application to nonlinear modeling of dynamic interaction of bundle conductors, vibration dampers and external wind flow. Such models are needed for efficiency analysis of existing galloping dampers and for efficiency modeling of new damper designs. The suggested approach can be used for mathematical design of hysteresis devices with other applications.