2019 ◽  
Vol 8 (2) ◽  
pp. 2160-2167

Power transformers constitute the most costly equipment which often posed constraints to electric power utility companies’ management. These transformers develop faults often due to oil insulation problems resulting from poor level of insulation oil, lack of routine maintenance, contamination, age, carbonization arising from system tripping as well as degradation of paper insulation due to ageing. However, the most economical way of maintaining stability in power supply to customers is creating a routine program of transformer oil regeneration for power transformer in the network. This paper therefore presents the optimization process of transformer oil regeneration for electric power utility company equipment. In this study, combined techniques of hot oil circulation, oil purification and oil reclamation of transformer oil regeneration was used for analysis of two 15MVA, 33/11kV power transformer. The process is aimed at drying the solid insulation of the transformer through the circulation of hot oil. The results of the transformer oil test before and after carrying out oil regeneration processes for the two 15MVA transformers are obtained and presented. For each transformer, the results are in five categories of properties namely; Physical, Electrical, Chemical, Dissolved metals and Dissolved gas analysis properties. The results indicated that the viscosity of transformer 1 is better than that of transformer 2. In addition, the dielectric breakdown voltage of oil transformer 1 is of more quality than the oil in transformer 2. The results are in agreement with standard ASTMD, IEC and ISO because the transformer properties has individual standard with each having its own mark. The comparison shows that transformer oil regenerated was very close to reality because the oil in the two power transformers is close to 90 %.


2015 ◽  
Vol 43 (2) ◽  
pp. 211-226
Author(s):  
Sobhy S. Dessouky ◽  
Adel El Faraskoury ◽  
Sherif Ghoneim ◽  
Ahmed Haassan

2019 ◽  
Vol 114 ◽  
pp. 04005
Author(s):  
Ngo Van Cuong ◽  
Lidiia I. Kovernikova

The parameters of electrical network modes often do not meet the requirements of Russian GOST 32144-2013 and the guidelines of Vietnam. In the actual operating conditions while there is the non-sinusoidal mode in electrical networks voltage and current harmonics are present. Harmonics result in overheating and damage of power transformers since they cause additional active power losses. Additional losses lead to the additional heat release, accelerating the process of insulating paper, transformer oil and magnetic structure deterioration consequently shortening the service life of a power transformer. In this regard there arises a need to develop certain scientific methods that would help demonstrate that low power quality, for instance could lead to a decrease in the electrical equipment service life. Currently we see a development of automated systems for continuous monitoring of power quality indices and mode parameters of electrical networks. These systems could be supplemented by characteristics calculating programs that give out a warning upon detection of the adverse influence of voltage and current harmonics on various electrical equipment of both electric power providers and electric power consumers. A software program presented in the article may be used to predict the influence of voltage and current harmonics on power transformers.


2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Nitin K. Dhote ◽  
Jagdish B. Helonde

Dissolved gas analysis (DGA) of transformer oil has been one of the most reliable techniques to detect the incipient faults. Many conventional DGA methods have been developed to interpret DGA results obtained from gas chromatography. Although these methods are widely used in the world, they sometimes fail to diagnose, especially when DGA results fall outside conventional methods codes or when more than one fault exist in the transformer. To overcome these limitations, the fuzzy inference system (FIS) is proposed. Two hundred different cases are used to test the accuracy of various DGA methods in interpreting the transformer condition.


2018 ◽  
Vol 216 ◽  
pp. 03011
Author(s):  
Sergey Barsukov ◽  
Sergey Pakhomov

The paper is aimed at developing a forecast model for estimating the service life of a diagnosed object based on the Neyman–Pearson method. It presents a procedure for selecting necessary and sufficient number of diagnostic indicators using the forecast model. The technique has been tested on the basis of a power transformer with a liquid dielectric. A condition-based operation strategy has been proposed for the transformer. According to this strategy, the iron impurity content in the dielectric liquid (oil) of the transformer should be measured every year of operation. Based on the forecast model, it is possible to calculate the variation of average risk (R) and a threshold value of iron impurity content in the transformer oil (k0) for each year of operation. Using these parameters, a reliable forecast model can be constructed to estimate the remaining service life of the transformer. The obtained relationships make it possible to identify a scientifically grounded stage in the service life of a diagnosed object, at which the number of measurable diagnostic indicators (indicators that are necessary for assessing the real technical condition of equipment) can be minimized.


Sign in / Sign up

Export Citation Format

Share Document