Classification and Analysis of Maintenance Data of Power Transformers

Large amount of information on maintenance history is accumulated during transformer’s service life including analysis of design, results of measurements and diagnostic tests, technical reports etc. A topical issue is to provide organized system for the viewing, archiving, and storage of above mentioned data to ensure more accurate survey on equipment's technical condition. In order to evaluate possible ways of obtaining additional information from accumulated statistical data, five classification methods of faults developed by various organizations are summarized in this paper, as well as verified on statistical data of power transformers in power transmission network in Latvia. Calculations, performed by Weibull cumulative distribution function, for determining service life of particular part of 2 power transformers are presented as a case study

Technical Condition and Remaining Lifetime Assessment Strategies of Power Transformers

Power transformer is one of the main elements in the power system. Therefore it is very important to pay sufficient attention to maintenance, diagnostic and lifetime issues. Assessment of power transformers is a complex task from both – technical (condition) and economical (benefits and costs) point of view. The traditional economical tool of a cost budget for each individual element of the organisation does not show the effect on the profit that maintenance has. Economic assessment is dependant on ‘transformer availability factor’ and failure rate of the transformer population, in other words, it’s very important to determine remaining lifetime. Maintaining the technical condition its economical life has a positive effect on the final economic results of the asset. Condition-based maintenance, prognostics and health management, and other types of power transformer maintenance strategies are considered and analyzed in this paper. To understand the role of predictive prognosis, one has to understand the relationship between diagnosis and prognosis capabilities. Diagnostic capabilities traditionally have been applied at or between the initial detection of a system, component, or subcomponent failure and complete system catastrophic failure. The risk, that power transformer will not in working condition by inner defect, decrease, if the operating personnel are trained and able to realize basic moments of these maintenance strategies. It is very important to transformer holder from economical side, especially nowadays

Development of Diagnostic Algorithm Based on Fault

The paper gives a short insight into the structure of Latvian high voltage transmission network. The situation in the field of power transformers’ diagnostics is analyzed, focusing mainly on the specific features of their maintenance in Latvia. Classification of the most commonly used dissolved gas analysis (DGA) data interpretation methods is given in this paper as well as causes for developing new methods are analyzed. Comparative diagnostic criterion is proposed which is based on typical gas concentration typical level

Power Transformer's Technical Condition Assessment by Dissolved Gas Analysis Considering Unit's Current Working Life Parameter

Classification of the most commonly used dissolved gas analysis (DGA) data interpretation methods is given in this paper as well as causes for developing new methods are analyzed. Comparative diagnostic criterion is proposed which is based on typical gas concentration typical level for separate groups of power transformers with varied current age. Transformers’ grouping principle and analysis of typical gas concentration of several representative DGA data samples are the main points of case study in which 224 power transformers with the voltage 110 kV in Latvian transmission network are reviewed

Overview of the Power Transformer Park and Diagnostic Methods in Latvia

Reliability of a power system depends on its equipment. As power transformers are essential elements in substations, reliability of power transmission system largely depends on their operating and technical conditions. Therefore complicated maintenance strategies are applied including various diagnostic methods and a thorough evaluation of the acquired results. Although diagnostic tests aid the evaluation of the technical condition, the risk assessment of a particular transformer is the next step in order to ensure certain reliability level. The risk assessment approach applicable for transformers in power transmission system in Latvia is proposed in this paper

Identification of Power Transformer's Failure and Risk Source

Power transformer is vital link in the chain of components constituting a power system, the failure of which affects the supply of electric power to the consumers. The transformers are found to be very reliable, but in some power systems of different countries the transformer’s tripping amount are quite high and majority of these accidents have ambient causes. The paper describes types of risk and the probable causes of failure of major equipment-power transformer and power system at all. There are some data of power system’s tripping causes and protective relaying. Also the proposals how to prevent fault or cause of failure are given

Measuring Specificities of Dissipation Factor of Electrical Equipment in Substations

Measuring techniques of dielectric losses tanδ of high voltage equipment are discussed and compared in this paper. There are several methods for determining tanδ and capacitance values in high voltage substation on site. Simple measuring methods like GST and UST can be put into practice without result corrections in ideal conditions. However electrical field in substation originates negative affect on measuring results, therefore different connection schemes of measuring methods have to be used

Advancements in Building Lightning Protection Zone Estimation

Lightning protection system is an effective way to properly protect structures against hazardous effects of lightning strike. Lightning protection zone is an essential parameter of lightning protection system, because it determines whether structure is protected against lightning strikes. The rolling sphere method is commonly used to estimate lightning protection zone, but it neglects some significant parameters such as differences in striking distance to ground and vertical masts, the lightning strike probability is the same irrespective of striking point, attachment process of downward and upward leaders and lightning discharge polarity. This paper review existing techniques that effectively eliminates these drawbacks