Indonesian Journal of Electrical Engineering and Computer Science, 2021
Vegetable oils have been an alternative to mineral oil for oil-immersed transformers due to conce... more Vegetable oils have been an alternative to mineral oil for oil-immersed transformers due to concern on less flammable, environmental-friendly, biodegradable, and sustainable resources of petroleum-based insulating oil. This paper presents the effect of electrical discharges (200 up to 1000 discharges) under 50 Hz inhomogeneous electric field on the properties (acidity, water content, and breakdown voltage) of two varieties of vegetable based insulating oils; i) natural ester (NE) and ii) low viscosity insulating fluids derived from a natural ester (NELV). Results show the water content, acidity and breakdown voltage of NE fluctuate due to applied discharges, while NELV display insignificant changes. Hence, results indicate that the low viscosity insulating fluids derived from natural ester tend to maintain their properties compared to natural ester.
Bulletin of Electrical Engineering and Informatics
Number of findings have shown that the used vegetable oils (UVOs) properties can be enhanced by c... more Number of findings have shown that the used vegetable oils (UVOs) properties can be enhanced by changing their chemical structure and can be utilized as dielectric liquid in oil-immersed transformers. However, earlier researchers used the one-factor-at-a-time (OFAT) method for their experimental design approach. Nevertheless, they failed to consider the possibility that combining the mixing process parameters at the highest ratios could produce a more favorable outcome. Hence, in this study, two-level (2k) factorial design is applied to achieve the highest color reduction of UVOs through chemical refining process known as refined-bleached UVOs (RBUVOs). The involved process parameters are oil temperature, mixing speed and mixing time. Based on the results of 23 factorial design, it is found that mixing time and oil temperature has the most significant effects on color reduction, with a percentage contribution of 35.00% and 32.51%, respectively. The result also shows that the best mi...
Indonesian Journal of Electrical Engineering and Computer Science, 2022
Condition monitoring of distribution and power transformers is of utmost importance to utilities ... more Condition monitoring of distribution and power transformers is of utmost importance to utilities due to cost effectiveness concerns. The common faults that occur in transformers are short circuits and winding deformation. To date, there are many established test methods used to detect these faults. In this study, three test methods (insulation resistance (IR), transformer turn ratio (TTR), and frequency response analysis (FRA)) were compared to assess their effectiveness in detecting short circuit and winding deformation in a three-phase transformer. Based on the results, the three test methods were found to be capable of detecting short circuits. However, only TTR and FRA can detect winding deformation, and FRA can further indicate which phase is faulty. Therefore, it is concluded that FRA is more effective in detecting short circuit and winding deformation of a three-phase transformer.
Power transformers studies have shown that the main cause of power transformers failures is the O... more Power transformers studies have shown that the main cause of power transformers failures is the On Load Tap Changer (OLTC). OLTC failure occurs due to the insulation degradation and contacts failure inside it. Other than that, contacts wear influences the OLTC performance and this phenomenon has not been deeply investigated. The worn contacts will cause hotspots in the OLTC tank and cause the insulating oil to degrade faster. Consequently, this will lead to the damage of complete transformer unit. Thus, the research work that has been carried out applied three different stages related to the diagnosis of OLTC. Firstly, fault detection of power transformer's OLTC is done mainly based on the results of the DGA interpretation by using the latest Duval Triangle method. Then, the results that obtained from latest Duval Triangle method are compared with the results carried out from Dynamic Current Measurement (DCM). Finally, research validation through visual inspection is applied to validate the results obtained from both DGA and DCM.
Bulletin of Electrical Engineering and Informatics
Recent studies have shown that modifying the chemical structure of used vegetable oils (UVOs) as ... more Recent studies have shown that modifying the chemical structure of used vegetable oils (UVOs) as an alternative dielectric liquid for oil-immersed transformers has improved these oils' physical, electrical and chemical properties. However, previous researchers have implemented the one-factor-at-a-time method as their experimental design approach. Therefore, they overlooked the possibility that combining mixing process parameters at optimum ratios will yield a better result. Hence, in this study, the two-level (2k) factorial design is applied to achieve the lowest acidity level of UVOs through chemical refining process namely as refined-bleached used vegetable oils (RBUVOs). The involved process parameters are oil temperature, mixing speed and mixing time. Based on the results of 23 factorial design, it is found that oil temperature has the most significant effect on acidity, with a percentage contribution of 35.76%. The result also shows that the best mixing process parameters o...
ARPN journal of engineering and applied sciences, 2016
Based on a theoretical perspective, the primary function of insulation oils is to dissipate heat,... more Based on a theoretical perspective, the primary function of insulation oils is to dissipate heat, and it serves as an insulator in between turn-to-turn windings in power transformers. To date, the majority of power transformer failures is attributed to the physicochemical reaction that takes place in the insulation oils due to the presence of heat, moisture content, oxidation and electrical stresses. Knowing that moisture content is one of the factors that leads to the degradation of transformer insulation oils, the main objective of this study is to examine the effects of moisture content on the breakdown voltage and Fourier transform infrared spectral characteristics of transformer insulation oils. Two types of insulation oils are chosen for this study: (1) conventional mineral-based insulation oil and (2) palm oil-based insulation oil which is a relatively new substitute for mineral-based insulation oils in Malaysia. The effects of moisture content is investigated by varying the ...
Distribution transformer is the key element in the electricity transmission throughout the nation... more Distribution transformer is the key element in the electricity transmission throughout the nation. Hence, serious attention for the transformer condition monitoring is a crucial. With an occurrence of short-circuit in the power system, the transformer active parts such as core and winding will experience a mechanical movement created by the electromagnetic forces. There are various types of transformer condition monitoring measurement in market, but the monitoring of the mechanical movement in transformer is still lacking. Therefore, Sweep Frequency Response Analysis (SFRA) has been introduced to assess any mechanical movement especially of the transformer's core and winding. The frequency response of the transformer provides mechanical information of core and winding conditions. The SFRA measurement results were validated using the actual transformer untanking process.
Bulletin of Electrical Engineering and Informatics, 2021
Transformer insulating oils are exposed to repeated electrical discharge or breakdowns inside pow... more Transformer insulating oils are exposed to repeated electrical discharge or breakdowns inside power transformers. Durability tests are conducted to analyze the ability of oil to resist decomposition due to such high electrical stresses. With the increasing demand for alternative insulating oils for oil-immersed transformers, it is worthy to compare the performance of different types of insulating oils (conventional mineral-based insulating oil and natural ester-based insulating oil) under repeated electrical breakdown. In this paper, the AC breakdown voltage of different mineral-based and natural ester-based insulating oils is reported. Durability tests were conducted based on the AC breakdown voltage behavior of insulating oils after 50 electrical breakdown shots. The AC breakdown voltage of each insulating oil sample was assessed according to the ASTM D1816 standard test method. Based on the results, it can be concluded that the dissimilarity in chemical composition of the insulat...
Indonesian Journal of Electrical Engineering and Computer Science, 2021
Vegetable oils have been an alternative to mineral oil for oil-immersed transformers due to conce... more Vegetable oils have been an alternative to mineral oil for oil-immersed transformers due to concern on less flammable, environmental-friendly, biodegradable, and sustainable resources of petroleum-based insulating oil. This paper presents the effect of electrical discharges (200 up to 1000 discharges) under 50 Hz inhomogeneous electric field on the properties (acidity, water content, and breakdown voltage) of two varieties of vegetable based insulating oils; i) natural ester (NE) and ii) low viscosity insulating fluids derived from a natural ester (NELV). Results show the water content, acidity and breakdown voltage of NE fluctuate due to applied discharges, while NELV display insignificant changes. Hence, results indicate that the low viscosity insulating fluids derived from natural ester tend to maintain their properties compared to natural ester.
Bulletin of Electrical Engineering and Informatics
Number of findings have shown that the used vegetable oils (UVOs) properties can be enhanced by c... more Number of findings have shown that the used vegetable oils (UVOs) properties can be enhanced by changing their chemical structure and can be utilized as dielectric liquid in oil-immersed transformers. However, earlier researchers used the one-factor-at-a-time (OFAT) method for their experimental design approach. Nevertheless, they failed to consider the possibility that combining the mixing process parameters at the highest ratios could produce a more favorable outcome. Hence, in this study, two-level (2k) factorial design is applied to achieve the highest color reduction of UVOs through chemical refining process known as refined-bleached UVOs (RBUVOs). The involved process parameters are oil temperature, mixing speed and mixing time. Based on the results of 23 factorial design, it is found that mixing time and oil temperature has the most significant effects on color reduction, with a percentage contribution of 35.00% and 32.51%, respectively. The result also shows that the best mi...
Indonesian Journal of Electrical Engineering and Computer Science, 2022
Condition monitoring of distribution and power transformers is of utmost importance to utilities ... more Condition monitoring of distribution and power transformers is of utmost importance to utilities due to cost effectiveness concerns. The common faults that occur in transformers are short circuits and winding deformation. To date, there are many established test methods used to detect these faults. In this study, three test methods (insulation resistance (IR), transformer turn ratio (TTR), and frequency response analysis (FRA)) were compared to assess their effectiveness in detecting short circuit and winding deformation in a three-phase transformer. Based on the results, the three test methods were found to be capable of detecting short circuits. However, only TTR and FRA can detect winding deformation, and FRA can further indicate which phase is faulty. Therefore, it is concluded that FRA is more effective in detecting short circuit and winding deformation of a three-phase transformer.
Power transformers studies have shown that the main cause of power transformers failures is the O... more Power transformers studies have shown that the main cause of power transformers failures is the On Load Tap Changer (OLTC). OLTC failure occurs due to the insulation degradation and contacts failure inside it. Other than that, contacts wear influences the OLTC performance and this phenomenon has not been deeply investigated. The worn contacts will cause hotspots in the OLTC tank and cause the insulating oil to degrade faster. Consequently, this will lead to the damage of complete transformer unit. Thus, the research work that has been carried out applied three different stages related to the diagnosis of OLTC. Firstly, fault detection of power transformer's OLTC is done mainly based on the results of the DGA interpretation by using the latest Duval Triangle method. Then, the results that obtained from latest Duval Triangle method are compared with the results carried out from Dynamic Current Measurement (DCM). Finally, research validation through visual inspection is applied to validate the results obtained from both DGA and DCM.
Bulletin of Electrical Engineering and Informatics
Recent studies have shown that modifying the chemical structure of used vegetable oils (UVOs) as ... more Recent studies have shown that modifying the chemical structure of used vegetable oils (UVOs) as an alternative dielectric liquid for oil-immersed transformers has improved these oils' physical, electrical and chemical properties. However, previous researchers have implemented the one-factor-at-a-time method as their experimental design approach. Therefore, they overlooked the possibility that combining mixing process parameters at optimum ratios will yield a better result. Hence, in this study, the two-level (2k) factorial design is applied to achieve the lowest acidity level of UVOs through chemical refining process namely as refined-bleached used vegetable oils (RBUVOs). The involved process parameters are oil temperature, mixing speed and mixing time. Based on the results of 23 factorial design, it is found that oil temperature has the most significant effect on acidity, with a percentage contribution of 35.76%. The result also shows that the best mixing process parameters o...
ARPN journal of engineering and applied sciences, 2016
Based on a theoretical perspective, the primary function of insulation oils is to dissipate heat,... more Based on a theoretical perspective, the primary function of insulation oils is to dissipate heat, and it serves as an insulator in between turn-to-turn windings in power transformers. To date, the majority of power transformer failures is attributed to the physicochemical reaction that takes place in the insulation oils due to the presence of heat, moisture content, oxidation and electrical stresses. Knowing that moisture content is one of the factors that leads to the degradation of transformer insulation oils, the main objective of this study is to examine the effects of moisture content on the breakdown voltage and Fourier transform infrared spectral characteristics of transformer insulation oils. Two types of insulation oils are chosen for this study: (1) conventional mineral-based insulation oil and (2) palm oil-based insulation oil which is a relatively new substitute for mineral-based insulation oils in Malaysia. The effects of moisture content is investigated by varying the ...
Distribution transformer is the key element in the electricity transmission throughout the nation... more Distribution transformer is the key element in the electricity transmission throughout the nation. Hence, serious attention for the transformer condition monitoring is a crucial. With an occurrence of short-circuit in the power system, the transformer active parts such as core and winding will experience a mechanical movement created by the electromagnetic forces. There are various types of transformer condition monitoring measurement in market, but the monitoring of the mechanical movement in transformer is still lacking. Therefore, Sweep Frequency Response Analysis (SFRA) has been introduced to assess any mechanical movement especially of the transformer's core and winding. The frequency response of the transformer provides mechanical information of core and winding conditions. The SFRA measurement results were validated using the actual transformer untanking process.
Bulletin of Electrical Engineering and Informatics, 2021
Transformer insulating oils are exposed to repeated electrical discharge or breakdowns inside pow... more Transformer insulating oils are exposed to repeated electrical discharge or breakdowns inside power transformers. Durability tests are conducted to analyze the ability of oil to resist decomposition due to such high electrical stresses. With the increasing demand for alternative insulating oils for oil-immersed transformers, it is worthy to compare the performance of different types of insulating oils (conventional mineral-based insulating oil and natural ester-based insulating oil) under repeated electrical breakdown. In this paper, the AC breakdown voltage of different mineral-based and natural ester-based insulating oils is reported. Durability tests were conducted based on the AC breakdown voltage behavior of insulating oils after 50 electrical breakdown shots. The AC breakdown voltage of each insulating oil sample was assessed according to the ASTM D1816 standard test method. Based on the results, it can be concluded that the dissimilarity in chemical composition of the insulat...
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