Abdul Rajab

Properties of RBDPO Oleum as a candidate of palm based-transformer insulating liquid

This paper presents properties of RBDPO Oleum to be used as an insulating liquid. RBDPO stand for Refined, Bleached and Deodorized Palm Oil. Electrical properties like breakdwon voltage, dielectric dissipation factor and relative permitivity of RBDPO Oleum were measured for three different temperature and compared to that of ASTM D-6871 standard. Physical and chemical properties like viscosity, acid number and water content are also investigated. Experimental results show that RBDPO oleum can be considered as an initial material for developing palm oil based-transformer insulating liquid. Breakdwon voltage of sample at room temperature, 25°C, is 57kV. The relative permtivity is 3.1, very closed to that of strandard, 3.2, while the dissipation factor is 0.03. Viscosity and water content of oil are significantly lower then those of ASTM D-6871 standard value. The remaining problems are reducing acid number wich are stil slightly above standard value.

Dielectric properties, partial discharge properties, and dissolved gas analysis of ricinnus oils as biodegradable liquid insulating materials

In this paper partial discharge (PD) characteristics of ricinnus oil and dissolved gas analysis (DGA) due to PD are investigated. The examination showed that the properties of ricinnus oil as a dielectric material such as breakdown voltage, dielectric constant, loss factor, neutralization number, and flash point complied with IEC standard. The φ-q-n pattern of PD and the change of the pattern with applied voltage were observed. Dissolved gas analyses due to PD in oil were also performed. The results were compared with ones in mineral oil which have been using as insulating materials in high voltage apparatus. The results showed that the PDIV of ricinnus oil is higher than one of mineral oil. Types and pattern of dissolved gas due to PD in ricinnus oil were similar with ones in mineral oil. The total combustible gas in ricinnus oil is a little bit higher than one in mineral oil. The measurement of the cumulative charge during 5 minutes showed that PD activity in ricinus oil is higher than one in mineral oil. The results showed that the gassing tendency due to PD of ricinus oil is good with small amount of combustible gases.

Study on streaming electrification properties of palm fatty acid ester (PFAE) oil due to aging

Palm fatty acid ester (PFAE) is mono ester oil which has better cooling property than mineral oil and other poly esters. Recently, natural ester has been tested on extra high voltage large power transformer. Large power transformers have a risk of streaming electrification. Many studies have been conducted to investigate streaming electrification properties of mineral oil immersed transformers and their countermeasures. However, streaming electrification properties of natural esters are rarely studied. Therefore, this paper presents a study on streaming electrification properties of PFAE due to aging. PFAE and mixed oils were prepared under several conditions. Aging test was conducted by heating the oil samples at 100 °C for 360, 720, 1080 and 1440 hours. The results show that heating causes various trends of volume resistivity and positive increases in electrostatic charging tendency (ECT) with respect to aging time. At initial state, ion dissociation on additive compound decreases volume resistivity and increases ECT. However, during the heating, the dissociation is not accelerated. Additive compound is dissociated into radicals to mitigate oxidation. In the mixture of 20% mineral oil and 80% PFAE, higher changes in volume resistivity and ECT indicate that degradation is more likely to occur in mineral oil part. In addition, air circumstance has effects on volume resistivity and ECT.

Low thermal fault gases of various natural monoesters and comparison with mineral oil

Natural ester oils began to be implemented in higher voltage of power transformer in 2002. Gases generated by such oils need to be examined in order to anticipate the use of dissolved gas analysis (DGA) method to diagnose the presence of faults in natural ester filled transformer in service. This paper deals with an analysis of the gas generations of natural monoesters of different molecular structures derived from palm and rice bran oils under localized and low thermal faults ranging from 200 to 300 °C. Types of gases and their generation rates at various temperature levels were investigated. An attempt is made to compare the gas generation tendency between tested oils and commercially available natural ester insulation oil reported in the previous literature as well as mineral oil. The phenomenon of ethane generation by fatty acid monoesters having C-C double bond in their hydrocarbon chains and those without C-C double bond are discussed. Due to the expectation of overheating temperature, the possible implementation of CO/CH4 gas ratio is also evaluated.

Comparison of low thermal fault gases of various fatty acid mono esters

Proven to be a good substitute for mineral oil as insulation in distribution transformer, natural ester oils have been implemented in higher voltage of power transformer since 2002. Gases generated by such oils need to be examined to diagnose the presence of faults in natural ester immersed transformer in service, based on dissolved gas analysis (DGA) method. In this paper, the gas generations of chemically modified natural esters which are palm fatty acid monoesters under low temperature overheating ranging from 200 to 300 °C were analyzed. Localized thermal faults were conducted to simulate the real condition in transformer operation. Experiment on several kinds of fatty acid monoesters with similar and different molecular structure as well as mineral oil were also performed for comparison. Types of gases, concentrations and their trend against temperature variation were investigated. The differences of generated gases between the fatty acid monoesters having C-C double bond in their molecular structure and those without C-C double bond are discussed. Comparison of the gas generation trend between tested oils and commercially available natural ester insulation oil reported in the previous literature, as well as mineral oil are also elaborated. The possibility of generating gas ratio method to expect the overheating temperature is also evaluated.

PD properties and gases generated by palm fatty acids esters (PFAE) oil

Partial discharge properties and gas generation of palm fatty acid ester (PFAE) oil of various moisture content levels are investigated under AC high voltage utilizing needle plane electrode configuration. Partial discharge inception voltage (PDIV) at various oil sample conditions are discussed. Variations of PD magnitude and PD number against voltage application change are analyzed. The effects of moisture content on PD properties and generated combustible gases of PFAE are also elaborated.

Study on static electrification of palm fatty acid ester (PFAE) oil using mini static tester

Palm fatty acid ester (PFAE) oil is an alternative insulating liquid of power transformer that has good biodegradable properties. As a part of insulating system of power transformer, PFAE should also has a low risk in term of static electrification that may degrade electrical strength of solid insulation due to charge accumulation at its surface during oil circulating. Charge potential value could describe the possibility of insulating oil in involving on charge accumulation at the surface of solid insulation. This can be calculated from charge density through electrostatic charge tendency (ECT) and volume resistivity. This study using mini-static-tester to measure ECT since it is easy to reproduce the specimen and suitable for standardization. Since PFAE has higher polarity than mineral oil, PFAE has larger charges than mineral oil. Even though static charges are estimated to generate on the pressboard surface easily, generated charges are estimated to escape from pressboard surface because of its lower resistivity. Variation of charge density and volume resistivity of several types (i.e. PFAE and mineral) and conditions (i.e. with-additives, non-additives, unused, and aged) of oil will influence to its charge potential.