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Any failures in these equipments directly reduce network reliability and increase maintenance costs. Consequently, the preventive maintenance techniques are increasingly developed. In this regard, frequency response analysis is an appropriate method in order to diagnose any change which occurs in transformer physical construction. This contribution has been concentrated on fault diagnosis by use of...
The many diagnostic tools (like Conventional oil test, DGA, DLA and RVM) are available.. From the test results, it is observed that the transformer which has very good result from these techniques and even minimum moisture content in the winding may / will have very poor mechanical integrity. Winding cellulose paper may be aged to such an extent (assessed from DP) that may sudden force or transient...
This paper contains summary information on Diacs technology principles comprising the following subjects: power transformers on-line testing and defects location procedure; on-line diagnostic technology and data analysis; examples of test results. Possible failure scenarios are observed here, as well as general tools available for power transformer life assessment. Specific technology of Diagnostic...
The diagnostic techniques to evaluate the internal condition of power transformer are presented in this paper. The techniques consist of electrical testing and insulating oil testing with their associated limitation to classify normal and abnormal conditions. The electrical diagnostics include exciting current, leakage impedance, ratio, DC resistance as well as core and winding insulation measurements...
This paper discusses the recently developed analysis method for service aged power transformers. This is a complete approach to assess the condition of a power transformer, both the on-load tap changer as well as the transformer windings. This paper also presents several case studies of tap changer defects that are discovered with the dynamic resistance measurement function.
Frequency response analysis (FRA) is a diagnosis method to detect troubles of a transformer, which are deformation and displacement of winging and so, by detecting change of a transfer function compared with that measured when the transformer is normal. However, identification of the troubles detected by FRA is not clear. In this paper, firstly, identification method of the troubles is investigated...
Since year of 2004 PLN P3B Jawa Bali has decided to apply a new strategy of maintenance, i.e.: condition based maintenance (CBM) to its high voltage assets. Transformer, which is the most crucial and expensive asset in electrical power network, becomes the first priority to be applied on. Performing FMECA (failure mode effect and criticality analysis) in order to find failure path of each transformer...
The dissolved gas analysis process is among the most widely used methods of diagnosing internal transformer faults. In Japan, judgment criteria have been established from the results of a questionnaire survey on DGA for 1,324 units of operating power transformers. The traditional dissolved gas analysis method of identifying abnormal modes perdorms less well at distinguishing between abnormalities...
One of the well-known methods of partial discharge (PD) localization in transformers is based on winding modeling. Although the method is theoretically precise, the reliability of the method is not known in practice, because of the difficulties that arise in high frequency modeling of the winding. In this paper, to investigate the reliability of the PD localization method in practical cases, different...
For many utilities the asset base is ageing at a time when the business focus is on system availability and energy not supplied. For the major plant items, such as generators, cables and transformers, where failure leads to long term unavailability, it is important to be able to define the risks of future operation. The processes used to achieve this have many common threads across the technologies,...
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