Měření voltampérových charakteristik pásek a laků používaných jako ochrana před klouzavými výboji u výstupu vinutí čel synchronních generátorů

The paper deals with measurement of coatings used in end-winding of synchronous generators as a protection against sliding discharges. These discharges are due to nonlinear distribution of the electric field along the stator coil. If this protection was not applied, at the machines with nominal voltage more then 5 kV the sliding discharges would appear, causing degradation of the insulation. This would result in more frequent machine shutdown, or worse, breakdown of the main insulation of the stator coil and the subsequent failure. By applying these coatings which consist of SiC particles and are characterized by non-linear current-voltage characteristic, the nonlinear distribution of the field gets linear and it leads to minimizing of surface discharges.