Dissolved Gas Analysis Method

Last YEAR PROJECT 1 PROGRESS REPORT 1 AUTHOR’S NAME:Ruban s/o Paramasivam STUDENT ID:EP083765 REPORTING PERIOD:18TH JUNE 2012 †15TH JULY 2012 SUPERVISOR’S:Mr. John Steven NAME PROJECT TITLE:Dissolved Gas Analysis in deciding Transformer Faults SUBMISSION DATE:16TH JULY 2012 1. 0 Background of Studies Oil inspecting investigation is a valuable, prescient, support device for deciding transformer wellbeing. DGA is recognized as one of the adequate strategy for oil testing in assessing transformer wellbeing. The breakdown of electrical protecting material inside the transformer creates gases inside the transformer.The character of gases being produced is helpful in any preventive strategy upkeep program. DGA technique includes oil examining strategy and testing the example to quantify the centralization of the broke down gases. The two commonplace chief reason for gas development inside a working transformer are electrical unsettling influence and warm disintegration. All transformers create gasses somewhat at ordinary working temperature. Protecting mineral oils for transformer are blends of various hydrocarbons and the deterioration procedure for these hydrocarbons are complex.During this procedure, dynamic hydrogen molecules and hydrocarbons pieces are shaped. These pieces can consolidate with one another to frame gasses, for example, Hydrogen (H2), Methane (CH4), Acetylene (C2H2), Ethylene (C2H4), Ethane (C2H6) and some more. The gasses recorded are viewed as ignitable. The rate at which every ga are delivered relies upon the temperature. In this manner, the convergence of the individual broke down gasses found in transformer protecting oil might be utilized legitimately to assess the transformer and recommend any shortcomings inside the transformer.After tests have been taken and investigated, the initial phase in assessing DGA result is to consider the fixation level of each gasses. Fundamentally, any sharp increment of the key gasses expre ssed above shows potential issue inside the transformer. The kind of deficiencies which the key gasses can deliver will be additionally talked about in the examination. Writing Review 2. 0 Dissolved Gas Analysis Power Transformers are loaded up with oil which goes about as a dielectric medium and furthermore as a warmth move specialist other than being an encasing to the transformer. The protected oil is comprised of soaked hydrocarbons.These particles are associated together to frame a chain loved way via carbon and hydrogen. [1] Table 1: Chemical structure of protecting oil and shortcoming gases During ordinary use, there is a moderate debasement of mineral oil which produces gases that break up in the oil, however when there is an electrical deficiency, the oil begins to corrupt and temperature rises. Various examples of gases are produced because of various powers of vitality dispersed by the kind of shortcomings. This happens as a result of the wrecked chain of the compound str ucture of the protecting oil.Therefore, the messed up chain will frame its own substance structure which is known as hydrocarbon gases or otherwise called flaw gases. It very well may be isolated into 3 classes which is Thermal warming, Corona and Arching, The most extreme force of vitality dissemination happens with angling, trailed by warm warming and the least serious is Corona. Figure 1 shows the way toward breaking chain inside the protecting oil compound structure of the flaw arcing, warm warming, and crown. Figure 1: Breaking chain procedure of shortcoming arcing, crown, warm warming and pyrolysis of celluloseGases which are delivered by the corruption of oil as a result of the expansion of temperature might be brought about by a few elements: [2] * serious over-burdening * lighting * exchanging homeless people * mechanical blemishes * substance deterioration of oil or protection * overheated regions of the windings * terrible associations which have a high contact obstructio n The sort of gases present in an oil test makes it conceivable to discover the kind of flaw that happens in the transformer. This is finished by assessing the convergence of gases present in the oil during maintenance.The sort of shortcoming and its attributes are as beneath [3]: * Arcing is the most extreme of all issue forms. Huge measure of hydrogen and acetylene are delivered, with minor amounts of methane and ethylene. Arcing happens in high present and high temperature conditions. Carbon dioxide and carbon monoxide may likewise be framed if the deficiency included cellulose. In certain examples, the oil may become carbonized. * Thermal warming Decomposition items incorporate ethylene and methane, along with littler amounts of hydrogen and ethane.Traces of acetylene might be framed if the flaw is extreme or includes electrical contacts. * Corona is a low-vitality electrical issue. Low-vitality electrical releases produce hydrogen and methane, with little amounts of ethane and ethylene. Practically identical measures of carbon monoxide and dioxide may result from release in cellulose. 2. 1 How DGA Works DGA strategy incorporates examining of oil inside the transformer at various areas. Chromatographic investigation will be done on the oil test to discover the convergence of broke up gas.The gases are then isolated, recognized and quantitatively decided with the end goal that the DGA technique would then be able to be applied so as to acquire solid finding [6]. The separated gases implied for examination design are Hydrogen (H2), Methane (CH4), Ethane (CH6), Ethylene (C2H4), Acetylene (C2H2), Carbon Monoxide (CO), Carbon Dioxide (CO2), Nitrogen (N2) and Oxygen (O2). These flaw gases can be ordered into 3 gatherings which are appeared in Table 2. Group| Hydrocarbons and Hydrogen| Carbon Oxides| Non-shortcoming Gases| CH4,H2,CH6, C2H4,C2H2| CO, CO2| N2, O2| Table 2 :Fault Gases GroupDepending on the centralization of the broke up gases, state of the transfor mer can be assessed. This is attainable in light of the fact that each sort of flaw consumes the oil in an alternate manner where it produces diverse kind of gases. Accordingly, it is anything but difficult to inspect the deficiency base on the gas discharged and its focus level. Table 3 : Relation between Fault type and Fault gases 2. 2 DGA Diagnostic Methods Insulating oil breakdowns to little amount of gases due to over electrical or warm pressure. In this manner, the creation of these gases assumes a job in deciding kind of fault.Through DGA indicative techniques, it is conceivable to discover blames as talked about before. There are numerous strategies in DGA and 5 techniques will be concentrated in this writing audit part. 2. 2. 1 Rogers Ratio Method The Roger’s strategy uses four gases proportions: CH4/H2, C2H6/CH4, C2H4/C2H6 and C2H2/C2H6. Finding if shortcomings are cultivated by means of a basic coding plan dependent on scopes of the proportion as appeared in tables underneath [4]. Table 4: Gas Ratio Codes [4] Table 5: Roger’s Ratio Code [4] The blend of the coding gives 12 unique sorts of transformer issues. The kind of flaws dependent on the code is appeared in table 6 beneath: [4]Table 6 : Classification dependent on Roger’s Ratio Codes 2. 2. 2 IEC Ratio Method This technique began from the Roger’s Ratio strategy, then again, actually the proportion C2H6/CH4 was dropped since it just demonstrated a restricted temperature scope of deterioration [3]. Here, the staying three gas proportions have various scopes of code when contrasted with the Roger’s proportion technique and they are appeared in table 7. The shortcomings are isolated into nine distinct sorts as recorded in table 8. [4] Table 7: IEC Ratio Codes [4] Table 8: Classification dependent on IEC Ratio Codes 2. 2. 3 Doenenbury Ratio MethodThis technique uses the gas fixation from proportion of CH4/H2, C2H2/CH4, C2H4/C2H6 and C2H2/C2H4. The estimation of the gases from the outset must surpass the fixation L1 to as certain whether there is actually an issue with the unit and afterward whether there is adequate age of every ga for the proportion investigation to be material [5]. Table 9 shows the key gases and their fixation L1 [5], and table 10 shows shortcoming kind of explicit proportions. Table 9: Concentration of L1 for Doernenburg Ratio Table 10: Fault conclusion for Doernenburg Ratio Method 2. 2. 4 Duval Triangle Method M.Duval built up this strategy during the 1960s. To decide if an issue exists at any rate one of the hydrocarbon gases or hydrogen must be at L1 level or above and the gas age rate is at any rate at G2. [6] The L1 level and the gas age rate for this technique are appeared in table 11. Table 11: L1 cutoff points and gas age rate for Duval Triangle Methode Once an issue has been resolved to exist, to acquire analysis, ascertain the complete gathered measure of the three Duval Triangle gases (CH4, C2H2, C2H4) and gap e very ga by the aggregate to discover the level of every ga of the total.Plot the rates of the aggregate on the triangle (Figure2) to show up at the determination [6] Figure 2: Duval Triangle Transformer Fault Diagnosis 2. 2. 5 Key Gas Method Figure 3 : Key Gases Diagnosis The rule of the Key Gas strategy depends on the amount of flaw gases discharged from the protecting oil when a shortcoming happens which thus increment the temperature in the force transformer. The nearness of the issue gases relies upon the temperature or vitality that will break the connection or connection of the protecting oil compound structure.This technique utilizes the individual gas as opposed to the computation of gas proportions for recognizing flaw. The noteworthy and extent of the gases are called â€Å"key gases†. Figure 3 show these â€Å"key gases† and relative extents for the four general issue types [5]. 3. 0 Scheduled Work Task| Start Date| Duration (days)| Remarks| Progress| Projec t Title Selection| 28. 05. 2012| 12| Proposed own venture title and submitted it on fourth June 2012| Completed| Research for Project Proposal| 08. 06. 2012| 10| Journals and articles were perused through in IEEE, Science Direct, Scopus| Completed| Project Proposal| 14. 6. 2012| 3| Project Proposal was done dependent on the diaries and articles found. | Completed | Resear