Multi-PD sources location by UWB RF detection on power transformers and a case study on-site

2008 ◽  
Author(s):  
Tang Zhiguo ◽  
Chang Wenzhi ◽  
Li Chengrong ◽  
Wang Caixiong ◽  
Zheng Zhong ◽  
...  
Keyword(s):  
Power Transformers

Faults and defects in power transformers - a case study

2009 ◽  
Author(s):  
Cacilda de Jesus Ribeiro ◽  
Andre Pereira Marques ◽  
Claudio Henrique Bezerra Azevedo ◽  
Denise Cascao Poli Souza ◽  
Bernardo Pinheiro Alvarenga ◽  
...  
Keyword(s):  
Power Transformers

scholarly journals Modelling of magnetostriction of transformer magnetic core for vibration analysis

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 803-808
Author(s):  
Janis Marks ◽  
Sandra Vitolina
Keyword(s):  
Power Transformer ◽  
Operation Mode ◽  
Magnetic Core ◽  
Power Transformers ◽  
Normal Operation ◽  
Elastic Deformations ◽  
Properties Of Materials ◽  
Transformer Core ◽  
Normal Operation Mode

Abstract Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. The aim of this paper is to create a model for evaluating elastic deformations in magnetic core that can be used for power transformers with intensive vibrations in order to eliminate magnetostriction as a their cause. Description of the developed model in Matlab and COMSOL software is provided including restrictions concerning geometry and properties of materials, and the results of performed research on magnetic core anisotropy are provided. As a case study modelling of magnetostriction for 5-legged 200 MVA power transformer with the rated voltage of 13.8/137kV is conducted, based on which comparative analysis of vibration levels and elastic deformations is performed.

scholarly journals Using the Analysis of the Gases Dissolved in Oil in Diagnosis of Transformer Bushings with Paper-Oil Insulation—A Case Study

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6713
Author(s):  
Tomasz Piotrowski ◽  
Pawel Rozga ◽  
Ryszard Kozak ◽  
Zbigniew Szymanski
Keyword(s):  
Positive Result ◽  
Gas Analysis ◽  
Power Transformers ◽  
Ratio Method ◽  
Dissolved Gas ◽  
Step Process ◽  
Lightning Impulse ◽  
Triangle Method ◽  
Inside Part

The article describes a case study when the voltage collapse during lightning impulse tests of new power transformers was noticed and when the repeated tests finished with a positive result. The step-by-step process of reaching the conclusion on the basis of dissolved gas analysis (DGA) as a key method of the investigations was presented. The considerations on the possible source of the analysis showed that the Duval triangle method, used in the analysis of the concentration of gases dissolved in oil samples taken from bushings, more reliably and unambiguously than the ratio method recommended in the IEC 60599 Standard, indicated a phenomenon which was identified in the insulation structure of bushings analyzed. Additionally, the results from DGA were found to be consistent with an internal inspection of bushings, which showed a visible trace of discharge on the inside part of the epoxy housing, as a result of the lightning induced breakdown.

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