According to the Josephson relations, dissipation in superconductors is related to the time-variation of the phase of the wavefunction. This physics is usually studied in the case of superconducting weak links, when a voltage develops across a thin barrier of nanometric dimensions. Although this kind of effect is typically observed in low-dimensional devices (for which at least one dimension is comparable to or smaller than the coherence length), there are some specific situations where it may arise in large systems as well. One particular case is that of phase slip lines in wide superconducting films, for which all the dimensions exceed the superconducting coherence length. Current-voltage characteristics display step-like structures, resulting from oscillations of both the amplitude and phase of the wavefunction. In this project, our aim is to experimentally study such current-voltage relations and the fluctuations of these quantities. We are specifically interested in the following questions: - determining the properties of dissipative carriers in the non-equilibrium state, - investigating possible correlations of these properties with the supercurrent component, - statistical study of conductance fluctuations in these dissipative states.