Several aspects of stator insulation condition based maintenance

The objective of power plant maintenance is to reduce the probability that an unforeseen forced outage takes place. Balancing maintenance with reliability is a key issue for the economical performance of a power plant. The paper shows that the turbo generator is the third cause for forced outages hours in a power plant. It will zoom into the generator failure statistics and show that the HV insulation system is the root cause for generator failure outage hours. Also the paper provides insight into the benefit of condition based maintenance (CBM) on the stator insulation system of generators. These benefits include: steering of insulation reliability, lengthening economical lifetime of the machine and decrease maintenance cost. A third topic of the paper is decision process from condition assessment to maintenance. This process is currently in use in some form or other at most power plants. Measurements are performed, interpreted and maintenance decisions are taken. However, this decision process is often not applied to its maximum efficiency. The main reason for this decreased efficiency is the problem of providing reliability numbers on the insulation system. The challenge of tomorrow would be to generate failure probability numbers based on measurements performed on machine insulation.