ORCID Profile
0000-0002-9669-569X
Current Organisation
Universiti Putra Malaysia
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Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2021
Publisher: Universitas Ahmad Dahlan
Date: 08-2018
Publisher: American Scientific Publishers
Date: 10-2017
Publisher: Penerbit UTM Press
Date: 02-12-2022
DOI: 10.11113/JURNALTEKNOLOGI.V85.18492
Abstract: Insulation oil is one of the most important components in an oil-insulated transformer. With the use of the dissolved gas analysis (DGA) tool, the condition of the transformer can be studied and predicted to prevent unwanted events from occurring. However, due to the rising of issues related to stray gassing phenomenon that causes false interpretations in the transformer condition, there is a need to find out the factors contributing to the formation of the stray gases in the transformer oil. In this research paper, thermal stress (85℃ and 120℃) on transformer oil with different transformer materials are studied to determine the effect towards the formation of stray gases in the transformer oil. The materials studied include diamond dotted paper, metal plate, coated metal plate, insulation glue and core metal. Both the uninhibited oil and inhibited oil are used for comparison. The metal plate, coated metal plate and core metal were found to be causing the generation of H2 gas at 120℃ while the cellulose ageing of insulation paper is causing the generation of CO and CO2 gases at 85℃ and above. The CH4 gas was found to be generated only at 120℃ and the insulation glue was determined to be the main cause for the C2H4 gas generation at 85℃ and above.
Publisher: Institute of Advanced Engineering and Science
Date: 05-2023
DOI: 10.11591/IJEECS.V30.I2.PP659-669
Abstract: This manuscript discusses the computation of electromagnetic forces on a disc-type winding due to a standard switching impulse (SSI). First, the resistances, inductances and capacitances (RLC) of a 30 MVA, 33/11 kV disc-type distribution transformer were estimated to obtain the winding equivalent circuit. The transient voltage waveforms for each of the disc layers and corresponding resonances of the windings under the SSI were then obtained in time domains. Next, the axial and radial force distributions in the disc winding due to the SSI were computed. The forces on each disc layer and along the disc windings due to the SSI were computed based on the analytical and numerical methods via the finite element method (FEM) respectively. The non-uniform switching impulse voltage distribution results in non-uniform force distribution along the disc winding. The magnitude of the axially directed force on the disc winding is found to be higher as compared to the radially directed force.
Publisher: MDPI AG
Date: 17-04-2019
DOI: 10.3390/EN12081466
Abstract: This paper presents an investigation on the resonant oscillations of an 11 kV layer-type winding transformer under standard and chopped lightning impulse overvoltage conditions based on calculated parameters. The resistances, inductances and capacitances were calculated in order to develop the transformer winding equivalent circuit. The impulse overvoltages were applied to the high voltage (HV) winding and the resonant oscillations were simulated for each of the layers based on different electrostatic shield placement configurations. It is found that the placement of grounded shields between layer 13 and layer 14 results in the highest resonant oscillation and non-linear initial voltage distribution. The oscillation and linear stress distributions are at the lowest for shield placement between the HV and low voltage (LV) windings.
Publisher: IEEE
Date: 12-2016
Publisher: Institute of Advanced Engineering and Science
Date: 04-2019
DOI: 10.11591/IJEECS.V14.I1.PP219-229
Abstract: span Frequency response measurements are used for power transformer winding failures detection. The variation between frequency responses indicate mechanical changes in the transformer winding. One method to investigate winding failures in transformer is to develop a reliable circuit model which can simulate the frequency response of an actual winding. The main reason to use the model is because it is expensive to create damages on an actual winding. This paper proposes n-stages circuit ladder network to simulate the response of a winding which has unique design. It presents a new technique to calculate the resistance, inductance and capacitance of the winding. Then, the relationship between the RLC parameters and the frequency response is studied. The winding chosen in this investigation is a single phase 33kV transformer winding. The simulated frequency response was compared with the measured response to verify the proposed model. The model can give a comprehensive understanding about the effect of RLC parameters on the frequency response. /span
Publisher: MDPI AG
Date: 02-09-2018
DOI: 10.3390/EN11092307
Abstract: This paper presents an investigation on the sensitivity of frequency response of a 500 kVA, 11/0.433 kV distribution transformer with and without the presence of a winding cl ing structure. Frequency response analysis (FRA) measurements of multiple test configurations were carried out with and without the presence of a winding cl ing structure. Statistical analyses based on Pearson’s correlation coefficient (PCC), Spearman’s correlation coefficient (SCC), Kendall’s correlation coefficient (KCC), cross-correlation coefficient (CCF), root mean square error (RMSE), absolute sum of logarithmic error (ASLE), hypothesis test (F-test) and relative factor (RF) were applied to determine the effect of the winding cl ing structure. It was found that the removal of the winding cl ing structure has an impact on the frequency response signature at the frequency less than 2 kHz during offline measurement. It was found that ASLE and F-test are suitable methods that can be used to indicate the variation of frequency response caused by cl ing structure removal of the distribution transformer under study.
Publisher: IEEE
Date: 11-2018
Location: United Kingdom of Great Britain and Northern Ireland
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