Assessment of insulation condition of hydro generator stator bars after 40 years in service

Abstract

Long-term field experience and the knowledge of the condition of stator bar insulation after long periods of operation are key points for ensuring reliable operation of stator windings. The ALSTOM Micadur® insulation system, first introduced for generators in 1958, has such long-term field experience. This system is in service over the whole power range of hydro and turbo generators, represented by a fleet of more than 10,000 machines between 5 MVA and 1944 MVA. ALSTOM had the opportunity to investigate the condition of 8 operation-aged Micadur® bars of a hydro generator, since the owner was replacing the stator core and stator winding.