Realistic condition assessment of medium-voltage substation

Incentive regulation forces German distribution system operators to continuous efficiency enhancements in maintenance and operation of their electrical energy supply power grids. Therefore, they permanently search for cost reduction and optimization possibilities. These include in particular optimized maintenance and replacement strategies for the grids. Basis of all further developed strategies is the most objective and realistic assessment of the condition of the various electrical grid components. In this contribution a simple, cost-efficient but reliable method for systematic condition assessment of medium voltage substations is presented. It is based on periodic visual inspections. Various field tests show that there are considerable spreads between the assessments carried out by different people. Based on this broad diversification a catalogue with typical damages has been developed to norm the assessments performed by various people. In order to further objectify the condition assessment, the method is complemented by suitable diagnostic methods which can be used without much additional effort. Therefore, different measurement methods and equipment have been tested in laboratory and in field. The results of the measurements are combined with the assessment points of the visual inspections to a significant and realistic condition assessment index of the medium-voltage substation.