Dissolved Gas Analysis Method

FINAL YEAR PROJECT 1 emanation REPORT 1 AUTHORS NAMERuban s/o Paramasivam STUDENT IDEP083765 REPORTING PERIOD18TH JUNE 2012 15TH JULY 2012 SUPERVISORSMr. John Steven NAME PROJECT TITLE fade away atom smasher epitome in ascertain Transformer Faults SUBMISSION DATE16TH JULY 2012 1. 0 primer of Studies Oil sampling summary is a useful, predictive, fear tool for determining transformer health. DGA is place as one of the sufficient order of pet procedureum sampling in evaluating transformer health. The breakdown of electric insulating material inside the transformer generates assailes within the transformer.The indistinguishability of gunmanes being generated is useful in every preventive rule maintenance program. DGA order involves inunct sampling method and testing the sample to prise the concentration of the fade out gases. The two typical principal cause of gas formation within an operational transformer ar electrical disturbance and thermic decomposition. All tr ansformers generate gasses to well-nigh extent at normal operating temperature. Insulating mineral oils for transformer ar mixtures of many distinct hydrocarbons and the decomposition process for these hydrocarbons argon complex.During this process, active hydrogen atoms and hydrocarbons fragments argon formed. These fragments can combine with for each one opposite to form gasses such as Hydrogen (H2), Methane (CH4), Acetylene (C2H2), Ethylene (C2H4), ethane (C2H6) and many more. The gasses listed ar considered combustible. The rate at which each gas are produced depends on the temperature. Therefore, the concentration of the individual dissolved gasses found in transformer insulating oil whitethorn be used directly to evaluate the transformer and suggest any open frames within the transformer.After samples drive home been taken and analysed, the firstborn step in evaluating DGA payoff is to consider the concentration level of each gasses. Basic tout ensembley, any sharp emergence of the tell gasses stated above indicates potential problem within the transformer. The character reference of ruptures which the key gasses can produce forget be further discussed in the study. Literature critical review 2. 0 Dissolved Gas compendium government agency Transformers are filled with oil which acts as a dielectric strong suit and also as a heat transfer agent anyhow being an insulator to the transformer. The insulated oil is made up of saturated hydrocarbons.These molecules are connected together to form a range of mountains liked air by carbon and hydrogen. 1 send back 1 Chemical construction of insulating oil and daub gases During normal use, there is a slow degradation of mineral oil which produces gases that dissolve in the oil, but when there is a electrical fault, the oil starts to degrade and temperature rises. Different patterns of gases are generated due(p) to opposite intensities of competency dissipated according to the fount of f aults. This happens because of the broken chain of the chemic social structure of the insulating oil.Therefore, the broken chain will form its own chemical structure which is known as hydrocarbon gases or also known as fault gases. It can be divided into 3 categories which is Thermal oestrus system, aureole and Arching, The nigh severe intensity of energy dissipation occurs with arching, followed by thermal heating and the least severe is Corona. hear 1 illustrates the process of breaking chain within the insulating oil chemical structure of the fault arcing, thermal heating, and corona. Figure 1 Breaking chain process of fault arcing, corona, thermal heating and pyrolysis of celluloseGases which are produced by the degradation of oil because of the increase of temperature may be caused by several factors 2 * severe overloading * lighting * switching transients * mechanical flaws * chemical decomposition of oil or insulation * overheated areas of the windings * bad connectio ns which name a high contact resistance The lawsuit of gases present in an oil sample makes it possible to find the display case of fault that occurs in the transformer. This is done by evaluating the concentration of gases present in the oil during maintenance.The type of fault and its characteristics are as below 3 * Arcing Arcing is the most severe of all fault processes. Large amount of hydrogen and acetylene are produced, with little quantities of methane and ethylene. Arcing occurs in high current and high temperature conditions. carbon copy dioxide and carbon monoxide may also be formed if the fault involved cellulose. In some instances, the oil may become carbonized. * Thermal heating Decomposition products accommodate ethylene and methane, together with smaller quantities of hydrogen and ethane.Traces of acetylene may be formed if the fault is severe or involves electrical contacts. * Corona Corona is a low-energy electrical fault. Low-energy electrical discharges pro duce hydrogen and methane, with small quantities of ethane and ethylene. Comparable amounts of carbon monoxide and dioxide may result from discharge in cellulose. 2. 1 How DGA lap ups DGA method includes sampling of oil inside the transformer at different locations. Chromatographic analysis will be done on the oil sample to find the concentration of dissolved gas.The gases are then separated, identified and quantitatively determined such that the DGA method can then be applied in order to witness reliable diagnosis 6. The extracted gases meant for analysis purpose are Hydrogen (H2), Methane (CH4), Ethane (CH6), Ethylene (C2H4), Acetylene (C2H2), ascorbic acid Monoxide (CO), Carbon Dioxide (CO2), Nitrogen (N2) and Oxygen (O2). These fault gases can be categorize into 3 groups which are shown in Table 2. Group Hydrocarbons & Hydrogen Carbon Oxides Non-fault gases Gases CH4,H2,CH6, C2H4,C2H2 CO, CO2 N2, O2 Table 2 Fault Gases GroupDepending on the concentration of the dissolved ga ses, condition of the transformer can be evaluated. This is achievable because each type of fault burns the oil in a different way where it generates different type of gases. Therefore, it is easy to examine the fault base on the gas released and its concentration level. Table 3 Relation between Fault type and Fault gases 2. 2 DGA Diagnostic method actings Insulating oil breakdowns to small quantity of gases due to over electrical or thermal stress. Thus, the composition of these gases plays a role in determining type of fault.Through DGA diagnostic methods, it is possible to find faults as discussed earlier. There are many methods in DGA and 5 methods will be studied in this literature review part. 2. 2. 1 Rogers Ratio regularity The Rogers method utilizes four gases ratios CH4/H2, C2H6/CH4, C2H4/C2H6 and C2H2/C2H6. Diagnosis if faults are accomplished via a simple coding scheme establish on ranges of the ratio as shown in tables below 4. Table 4 Gas Ratio Codes 4 Table 5 Rogers Ratio Code 4 The compounding of the coding gives 12 different types of transformer faults. The type of faults based on the legislation is shown in table 6 below 4Table 6 Classification based on Rogers Ratio Codes 2. 2. 2 IEC Ratio Method This method originated from the Rogers Ratio method, except that the ratio C2H6 /CH4 was dropped since it only indicated a limited temperature range of decomposition 3. Here, the remaining three gas ratios have different ranges of code as compared to the Rogers ratio method and they are shown in table 7. The faults are divided into nine different types as listed in table 8. 4 Table 7 IEC Ratio Codes 4 Table 8 Classification based on IEC Ratio Codes 2. 2. 3 Doenenbury Ratio MethodThis method utilizes the gas concentration from ratio of CH4/H2, C2H2/CH4, C2H4/C2H6 and C2H2/ C2H4. The value of the gases at first must exceed the concentration L1 to as certain whether there is unfeignedly a problem with the unit and then whether there is sufficient contemporaries of each gas for the ratio analysis to be applicable 5. Table 9 shows the key gases and their concentration L1 5, and table 10 shows fault type of specific ratios. Table 9 Concentration of L1 for Doernenburg Ratio Table 10 Fault diagnosis for Doernenburg Ratio Method 2. 2. 4 Duval Triangle Method M.Duval developed this method in the 1960s. To determine whether a problem exists at least one of the hydrocarbon gases or hydrogen must be at L1 level or above and the gas contemporaries rate is at least at G2. 6 The L1 level and the gas generation rate for this method are shown in table 11. Table 11 L1 limits and gas generation rate for Duval Triangle Methode Once a problem has been determined to exist, to obtain diagnosis, calculate the total accumulated amount of the three Duval Triangle gases (CH4, C2H2, C2H4) and divide each gas by the total to find the percentage of each gas of the total.Plot the percentages of the total on the triangle (Figure2) to arrive at the diagn osis 6 Figure 2 Duval Triangle Transformer Fault Diagnosis 2. 2. 5 come upon Gas Method Figure 3 Key Gases Diagnosis The rationale of the Key Gas method is based on the quantity of fault gases released from the insulating oil when a fault occurs which in turn increase the temperature in the power transformer. The presence of the fault gases depends on the temperature or energy that will break the link or relation of the insulating oil chemical structure.This method uses the individual gas rather than the calculation of gas ratios for detecting fault. The evidentiary and proportion of the gases are called key gases. Figure 3 indicate these key gases and relative proportions for the four general fault types 5. 3. 0 Scheduled Work Task Start Date Duration (days) Remarks Progress see to it deed Selection 28. 05. 2012 12 Proposed own project title and submitted it on quaternate June 2012 Completed Research for interpret final cause 08. 06. 2012 10 Journals and articles were brow sed through in IEEE, Science Direct, Scopus Completed Project Proposal 14. 6. 2012 3 Project Proposal was done based on the journals and articles found. Completed Research for Literature Review 19. 06. 2012 unknown Journals and articles were searched for the literature review Ongoing Progress Report 1 01. 07. 2012 15 Each progress towards the completion of Final Year Project 1 Completed Research / Oral initiation Preparation 17. 07. 2012 24 Complete the literature review and getting prepared for the oral presentation while doing research for the project Incomplete Oral Presentation 10. 08. 2012 / 29. 08. 012 - Presentation of all the findings and research and logbook to be submitted Incomplete Progress Report 2 10. 08. 2012 3 Each progress towards the completion of Final Year Project 1 Incomplete 4. 0 Conclusion In the end of this study, Ill be able to determine the pros and cons of all the different types of DGA diagnostics methods and be able to determine transformer faults ou t of the diagnostic methods which are very congenital to prevent transformer damage. Suggestions and recommendations will be given to further improve the susceptibility of those available diagnostic methods . 0 Reference 1. Church, J. O. , Haupert, T. J. and Jakob, Fredi (1987). Analyze Incipient Faults with Dissolved-gas Nomograph. Elecrical World. Oct. Pgs. 40-44. 2. DiGiorgio, Joseph B. (1997). Dissolved Gas Analysis of Mineral Oil Insulating Fluids. California Northern technology & Testing 3. Domun, M. K. (1996). Condition Monitoring of Power Transformers by Oil Analysis Techniques. Proc. of the 11th Conference on Electric Power Supply intentness (CEPSI). Kuala Lumpur, Malaysia 4. Siva Sarma, D. V. S. S. and G. N. S.Kalyani, ANN Approach for Condition Monitoring of Power Transformers using DGA. 2004 IEEE persona 10 Conference, TENCON 2004. , 2004. C p. 444-447. 5. C57. 104. 1991, I. , IEEE Guide for Interpretation of Gases Generated in Oil-Immersed Transformer, I. The In stitute of electrical and Electronic Engineers, Editor. 1992, The Institute of Electrical and Electronic Engineers, Inc p. 27 6. FIST3-31, Facilities Instructions, Standards and Techniques Volume 3-31 Transformer Diagnostics. 2003, Bureu of reclamation Hydroelectric Research and Technical Services Group Denver. p. 5-13.