An Integrated Probabilistic Approach for Power Transformers Availability

The paper present an integrated approach of power transformers availability considering 7 high power 110/6.3 kV and 20 years as the monitoring time interval. With respect to a given load point, the interruptions frequency, duration and cause are revealed on a statistical bases. Not only the PTs and their unavailability but also the surround equipment like circuit-breakers, feeder and load point events were included as interruption sources. For PTs, internal and external failures as well as the planned (maintenance) events were considered.Time to failure, time to repair, mean time between events and its progress over time were probabilistically estimated. The results allow for a better maintenance management and for a good estimation of the quality of supply.