FAILURE ANALYSIS OF A POWER TRANSFORMER USING DISSOLVED GAS ANALYSIS – A CASE STUDY (original) (raw)
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Dissolved Gas Analysis as a Diagnostic Tools for Early Detection of Transformer Faults
Transformers is a device on which cost effective supply of electricity mostly depends. Hence, to manage the life of transformers, to reduce failures and to extend the life of transformer, some measures are being adopted. Dissolved gas-in-oil analysis (DGA) is a common practice in transformer fault diagnosis. Some classical methods that depend on gases concentration in transformers oils are used to interpret transformer faults such as Dornenberg, Rogers, Duval triangle and key gases methods. These methods in some cases did not give the same results; therefore, an expertise method is developed to give the fault type according to the dissolved gases concentration in oil. A software code is designed using logic functions to get the type of the faults in transformers. Comparing the results from this software with the real laboratory cases as well as some cases in literatures is developed. The results explain the validation of software to detect the fault in transformer.
Condition Monitoring of Power Transformer Using Dissolved Gas Analysis of Mineral Oil: A Review
International Journal of Advance Engineering and Research Development
Condition Monitoring plays a vital role in asset management plan. Power Transformers are most important and critical component in electrical power transmission and distribution. To have a reliable electricity supply it is necessary to give considerable attention to maintenance of the transformer. To maximize the lifetime and reliability of transformers, it is important to be aware of possible faults that may occur and to know how to prevent them. Since a fault in a transformer can have a huge repercussion when failures occur, and as, number of transformers and of those that are difficult to operate in overload conditions is on the rise, it is important to detect incipient faults in a transformer and forecast and prevent failures These faults can all lead to the thermal degradation of the oil and paper insulation in the transformer. The composition and quantity of the gases generated depend on the types and severity of the faults, and regular monitoring and maintenance can make it possible to detect incipient flaws before damage occurs. Any failure in transformer leads to malfunction of whole power system. Unfortunately, the failure rate of these transformers is very high in India, 25 % per annum, which is not favourable as compared to international units of 1-2 %. Failures happen due to internal reasons or operational hazardless. Transformer insulation deteriorates as the function of temperature, moisture and time. The core and winding losses, stray losses in tank and metal support structures are the principle sources of heat which cause oil and winding temperature rise. There are multiple reasons for overheating such as improper cooling, excessive eddy currents, bad joints, blocked radiators, overloading, improper earthing and harmonic contents in power supply. This leads to accelerated aging of oil and cellulosic solid insulation, which generate the gases within transformer and further leads to permanent failure. To prevent such failures, effective analysis and diagnosis needs to be investigated. The type of gases generated and amount of gas concentrations in oil efficiently evaluated using Dissolved Gas analysis (DGA).Generally the degradation products are gases, which will get dissolve in the oil entirely or partially. In the oil these gases are easily detected at the ppm level by dissolved gas analysis. Dissolved gas analysis (DGA) is a widely used most powerful method to detect incipient faults on oil filled electrical equipment. The electrical equipment may be a transformer, a load tap changer or a cable Dissolved Gas Analysis (DGA) of transformer oil is the best indicator of a transformer's overall condition. Hence this widely accepted method is used in routine maintenance of power Transformers. Transformer oils perform at least four functions for the transformer. Oil provides insulation, provides cooling, and helps extinguish arcs. Oil also dissolves the gases which are generated due to degradation of oil, moisture and gas from insulation, deterioration of cellulose, and gases and moisture from the surrounding the oil is exposed to. Any deterioration in the oil can lead to premature failure of the equipment. The most common type of oil used in transformers is of a mineral oil origin.
Transformer Failure Detection Using Dissolved Gas Analysis (DGA
Quist Mirable Jetrho, 2020
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductorsthe transformer coils. Transformer is very important and plays a vital role when it comes to transmission and distribution of electrical energy. Transformer failures are disruptive to electrical grid and costly. Transformer insulation failures from various blasts like bombs or lightning strikes are major culprits. Methods and techniques used in data collection, analyses, computer simulation and results interpretation on transformer failures are presented. Dissolved Gas Analysis (DGA) of the insulation was used to detect the health condition of transformers. Secondary data of burnt transformers were also considered. A multi-layer casing for transformers was designed to protect transformers. The casing will protect transformers from detonation by bombs, rocket and other explosives, and lightning strikes. A stabilized power supply will mean higher productivity in the country as a result of good energy supply.
Condition Monitoring of Power Transformer by Dissolved Gas Analysis: A Review
Advances in Power Systems and Energy Management, 2021
A power transformer is pivotal in-stream equipment in the overall power system and suffers countless internal and external stresses throughout its lifespan [1-2]. Therefore, it must be monitored and inspected throughout the operation. The transformer has electrical windings, which embrace paper insulation soaked in oil insulation, both are important sources to evaluate incipient faults and thus reflect the health of the transformer. Transformer oil performs many functions: provides insulation, helps extinguish arcs and provides cooling [1]. Oil and paper insulation mainly decompose during thermal and electrical stresses. Consequently, the heat dissipation capacity and dielectric strength of paper and oil decreases and some gases are released [3, 4]. From the amount and composition of gases, it is evaluated whether there is an internal irregularity or not and how critical it is.
Conventional Dissolved Gases Analysis in Power Transformers: Review
Energies
Transformers insulated with mineral oil tend to form gases, which might be caused by system faults or extended use. Based on an evaluation of the main failure analysis techniques using combustible gases, this study reviewed the conventional techniques for Dissolved Gas Analysis (DGA), present in the norms IEC 60599 and IEEE Std C57.104, and their failure analysis tendency. Furthermore, to illustrate distinct technique performances and failures, the performance of the following techniques was analyzed based on the IEC TC10 database: Dornenburg, Duval Triangle, Duval Pentagon, IEC ratio method, Key Gas, and Rogers. The objective of this work was to present relevant information to support students and professionals who work in failure analysis and/or assist in the development of new tools in the DGA field.
Dissolve Gas Analysis is one of the widely used technique for recognition of incipient fault of oil immersed transformer. The transformer is a very important and critical component of power system. There is a need of proper maintenance and regular diagnosis of incipient fault within transformer oil. The main cause of transformer failure is ageing, deterioration and damage of insulating material. When insulating material is subjected to any incipient fault, combustible gases are generated. These combustible gases are known as key gases. By analysing these gases transformer fault can be detected. This paper represents a review of different DGA methods. The existing DGA diagnostic method consists of mainly Key Gas method, Ratio method (Rogers and Doernenburg and I.E.C. ratio) and Percentage Gas method (Duval triangle).
Diagnostic Tool for Transformer Fault Detection Based on Dissolved Gas Analysis
IOSR Journal of Electrical and Electronics Engineering, 2014
Dissolved gas analysis (DGA) is a diagnostic tool that used to detect the incipient faults of power transformers through the correlation between the content of gases dissolved in transformers oil and a particular malfunction. Transformer failures are often due to the lack of the dielectric strength of oil insulation and will lead to a negative impact on electrical power systems. Early stage detection of transformer faults can reduce considerably the cost of repairing the damaged transformers and hence maintain the stability of the system. Some classical methods that depend on gases concentration in transformers oils are used to interpret transformer faults such as Dornenburg, Rogers, Duval triangle and key gases methods. These methods in some cases did not give the same results; therefore, an expertise method is developed to assess the kind of fault based on the DGA. A software code is designed using logic functions to get the type of the faults in transformers from laboratory data DGA based. A comparison between the laboratory results and the code results will be accomplished. This comparison explains that the code is reliable to determine the transformer fault. The age of transformer is taken into account in our calculations. The results from the software code illustrate the program reliability as an early detection tool of transformer faults.
Dissolved Gas Analysis of Power Transformers
TJPRC, 2013
Transformer insulation aging diagnosis is important for all the condition assessment Dissolved gas analysis (DGA) is one of the most useful techniques and tools to detect the incipient faults in large oil filled transformers. Various methods have been developed to interpret DGA results. Among them are the Key Gas, Rogers Ratio, Logarithmic Nomo graph, Dorenenburg, IEC Ratio and Duval Triangle. This paper uses the DGA data from different cases to test the accuracy and consistency of these methods in interpreting the transformer condition. It also describes the structure and specific features of transformer insulation ageing diagnosis based on artificial neural networks. MATLAB programs using neural network were developed to automate. Also this paper present three fault type, partial discharges (PD), discharges, thermal faults.
Journal of Electrical Systems, 2016
This paper presents methodologies for power transformer fault diagnosis using dissolved gas analysis and electrical test methods. These methods are widely used in determination of inception faults of power transformers. Dissolved gas analysis test provides fault diagnosis of power transformers. On the other hand the electrical test methods are used for detection of root causes and fault locations and they provide more specific information about the faults. The aim of this work is to study the faults that are measured and recorded in Turkish Electricity Transmission Company (TEIAS) power systems. For this purpose, four specific cases are considered and analyzed with dissolved gas analysis and electrical testing methods. Three of these cases are defective situations and one case is a non-defective situation. These real cases of measurements have been analyzed with both methods in detail. Assessment results showed that a single method cannot yield accurate enough results in some specif...
ELEKTRIKA- Journal of Electrical Engineering, 2019
This article presents alternative analyzing method of extracted dissolved gases related to insulating oil of power transformers. Analysis of soluble and free gas is one of the most commonly used troubleshooting methods for detecting and evaluating equipment damage. Although the analysis of oil-soluble gases is often complex, it should be expertly processed during maintenance operation. The destruction of the transformer oil will produce some hydrocarbon type gases. The development of this index is based on two examples of traditional evaluation algorithms along with fuzzy logic inference engine. Through simulation process, the results of the initial fractures in the transformer are obtained in two ways by the "Duval Triangle method” and "Rogers’s ratios". In continue, three digit codes containing the fault information are created based on the fuzzy logic inference engine to achieve better results and eliminate ambiguous zones in commonly used methods, especially in th...