Reliability centered maintenance using a predictable strategy - application for 20kV traction transformers

The desired outcome of any maintenance input is not just to repair failures but also to prevent them. Maintenance is one of the critical and most costly phases in the lifecycle of any power systems. Through improved maintenance management, the system reliability can be improved. The maintenance approach is addressed as a predictive strategy, avoiding even more costly non productive time due to downtime caused by failures induced by maintenance. Condition monitoring and assessment is described as one of the effective tools in the maintenance engineer´s armory to apply a predictive approach. Such an approach is described in this paper by applying in the field of 20kV Traction Transformers of Athens Metro in Greece. The available historical data of their operation since 2000 are used effectively.