Experience with insulation condition monitoring on a 1050 MW generator

There are a number of offline condition monitoring tools that have historically been used to establish the state of machine insulation. Online insulation condition monitoring tools are a relatively new development and have not yet established themselves as an industry standard. Eskom was presented with an insulation problem, which on first analysis indicated that an immediate repair should be undertaken. By integration of the information provided by the classical offline and newly introduced online techniques it was decided to continue running the machine. The latest detailed offline investigation vindicated this decision.