The transformers are one of the most important and most expensive elements of the electrical energy transmission networks. Their outage of work results power energy supply issues, their maintenance or replacement results significant expenses, therefore their condition are widely important to follow with attention. Their operational reliability are affected by many factors (i.e. the condition of the insulation, the mechanical condition of the appliance, weather and climate conditions), accordingly their diagnostic requires a complex system.
The Transformer Status Indicator (TSI) expert system was developed by the High Voltage Laboratory of the Budapest University of Technology and Economics Electric Energetics Professorship. By the help of it we can get an up-to-date and extensive view of the transformer's actual condition.
On my thesis I deal with the oil insulated, high/middle voltage transformers. On the first half of it I introduce the diagnostic methods which are relevant for the TSI expert system (i.e. dissolved gas analysis, universal oil analysis, recovery voltage measurement) of their measuring methods and their result evaluation point of view.
On the second half of my thesis I present the calculating method of the TSI expert system and then I compare two concrete transformer’s TSI calculating results with the results of my own calculating methods. I inspect the Condition Assessment of Power Transformers titled study of CIGRÉ working group, which deals with the condition diagnostic of the power transmission transformers. I compare the limit values of the study's diagnostic methods with the value limits the TSI expert system uses, and in light of this I make proposals for the development of the present system.