Pdf failure analysis of distribution transformers a case study. Combining failure statistics with life determination models for paper insulation. In distribution side transformers there are commonly two. Though they are some of the most reliable component of the electrical grid they are also prone to failure due to many factors both internal or external.
Failure of distribution transformers causes capital loss and loss of revenue to the nation. New hi parameters, an age distribution and logistic regression model were determined, enabling a higher accuracy in predicting failure events and can therefore be utilized in various asset management initiatives and risk mitigation. Types and construction of power and distribution transformers. This paper will address the transformer failure statistics over the last 5 years, the aging of our. Pdf analysis of distribution transformers failures was carried out in ughelli. Analysis of transformer failures imia 2003 5 overloading this category pertains to those cases where actual overloading could be established as the cause of the failure. In india the maximum distribution transformer is damaged due to overloading, but still there is no any smart protection is applied for it due to its high cost.
Key difference between power transformer and distribution transformer. Transformer fuse operations are the most common equipment failure on distribution systems, comprising as much as 40% in one study 4. An important portion of transformers present failure rates 45 times higher than normal, and very large overhead lines. Lightning effects on distribution transformers and reliability. If you mean what is the failure rate of the transformer as a part before it ends up in the product, it should be very, very low. A statistical approach to processing power transformer. Some of the most commonly occurring failures of the transformer and their causes are listed below.
This computational tool is applied to assist the management in about 61. Over the years, hsb has investigated thousands of transformer losses. Actom distribution transformers plays a vital role in the electrical distribution chain. An analysis of transformer failures, part 1 1988 through 1997 transformers losses are significant. Transformers plays a very important role in the power system. It plays important roles both in transmission and in distribution system by. Internal fault detection in distribution transformers. Also captured is the impact of distribution losses on upstream facilities, i. Introduction transformer is a static machine with very high efficiency and rugged construction. Among the materials consulted while preparing this book are. I introduction t his paper presents an integrated management system for distribution transformer loading based on the methodology described in the references 1, 2 and 3. Also information about some types of transformers are gathered as well as distribution transformer connections installations.
One other advantage of newly designed protection system of transformer is it having inbuilt thermal overload protection in distribution transformer. If the heat inside of a transformer is not properly dissipated, the temperature of that transformer will rise continually, which will damage the insulation over time. To estimate instrument transformer reliability, we use an analysis called the maximum likelihood method. Jul 29, 2014 it completely depends on the design it lands in. Keywords transformer failure, insulation failure, harmonics, power quality pq, distribution transformers. Before joining beckwith electric, performed in application, sales and marketing management capacities at powersecure, general. The premature failure rate of distribution transformers is above 25% in some of the regions of. Reports in eskom distribution indicated that a number of cts from one manufacturer were exceeding the specified insulation power factor value. This method is based on the observation that the log of the time to failure is approximately a normal distribution. Distribution transformer population in tnb is approaching 74,000 units with rated capacity from 100 kva to kva installed in its distribution network. Management system of distribution transformer loading. Distribution automation handbook prototype elements of power d istribution systems 1mrs757959 4 3 elements of power distribution systems 3. Power transformer is one of the most important electricity equipment in power system. Eventful transformer failures eventful transformer failures describe a tank failure where the tank is visibly damaged due to an internal fault.
The documents you intend to merge can be in any of the supported image formats. Distribution network load distribution strategy considering the economy of parallel transformers is put forward in this paper. Rootcause analysis of transformer failure scenario at power. Estimation of distribution transformer losses in feeder. Although the term scheduled discard is used throughout this paper, please read it as scheduled discard andor scheduled restoration.
Due to transport limitation and for convenience of storagehandling at site, if a unit can be dispatched completely assembled then the transformer is usually dispatched from the factory with. The invention of a practical efficient transformer made ac power distribution feasible. Abstractdistribution transformer is an essential link in the distribution system. Distribution transformers are normally considered to be those transformers which provide the transformation from 11 kv and lower voltages down to the level of the final distribution network. Failure is when the transformer was scrapped after the fault nonrepairable, catastrophic failure is when either an explosion or fire occurred. In the uk this was, until january 1995, 415 v threephase and 240 v phase to neutral. Distribution transformer is an essential link in the distribution system. Distribution transformer handbook is packed with practical information on transformer concepts, singlephase and threephase transformer connections, and procedures for installing overhead and padmount transformers. Difference between power transformer and distribution transformer. If it is a high frequency transformer then the risk would primarily. Rootcause analysis of transformer failure scenario at.
Failure investigation consists of many steps in accurate sequence to conclude a significant outcome for transformer failure. The rate of failure of distribution transformers in india is higher 1217% as compared to developed countries 23%. Minimize the failures of distribution transformer seminar. Table 4 displays the distribution of transformer failures by age. It is dry type based pole mounted single phase distribution. Analysis of power transf failure in trans utilities 15. This method is based on the observation that the log of the. Wellillustrated, this reference helps everyone install and maintain transformers correctly, quickly, an. New niyantra 20 distribution transformer fuse failure. Illustration of concept of transformer failure 20, 21.
Distribution transformers can be shipped complete in standard shipping container. A schematic drawing of a singlephase distribution transformer appears in fig. That is, the highest failure rates are in the first few years of service and then decline. Difference between power transformer and distribution transformer here we will discuss, the difference between power transformer and distribution transformer. Individual failure rates for transformers within a. The distribution transformer is used to bring down or step down the voltage and current level of a transmission line to a predefined level, which is called safety level for the enduser consumer in domestic and industrial purpose.
Minimize the failures of distribution transformer seminar report pdf ppt download abstract. As you are aware, the distribution sector has a large number of distribution transformers of several capacities. Distribution transformer installed stocks growth rate 6. National institute of technology, hamirpur hp india. The overloading which continues for longer time is dangerous as it causes overheating of transformer and it will result in the failure of transformer. Repair and maintenance practice frequency of repair and failure, spare parts. As an object class, transformers have consistently been ranked in the top five objects for claims paid by hartford steam boiler during the past several decades. Abstract distribution transformer is an essential link in the distribution system. Due to the overheating of transformer other problems arises are failure of cooling system, though rare, increase in. Title failure analysis of power transformer based on fault. The premature failure rate of distribution transformers is above 25% in some of the regions of the state of madhya pradesh m. Abb offers a complete range of distribution transformers designed to grant the reliability, durability, and efficiency required in utility, industrial, and commercial applications.
It is thus very important to avoid transformer failure. The high rate of failure of secondary distribution transformer in power systems may perhaps be described as 0ne of the tragedies of distribution system management of present times especially in developing countries like india. Power input to a transformer is not all delivered to the secondary load. Distribution transformer handbook alexander publications. Transformer overloading and assessment of lossoflife for liquidfilled transformers. Note the fused cutout and lighting arrestor combination external to the transformer. The difference is categorized on the factors like the type of network used, location of installation, usage either for low voltages or high voltages.
The basic principle of operation of a transformer is explained in chap. Pdf causes of transformer failures and diagnostic methods. Any failure of these transformers is bound to cause great inconvenience to the consumers and huge financial losses to the utilities. Transformer causes of failures the fault that most frequently occur in practice may be classified broadly as follows, although to a large extent the different kinds often react upon one another. Causes, prevention, and maximum service life introduction over the years, hartford steam boiler has investigated thousands of transformer failures, compiling an extensive database of loss information. Estimation of distribution transformer losses in feeder circuit. Thermal overload protection of distribution transformer. The foil windings combine a simple winding technique with a high degree of. Practical approach for detection of failure of distribution transformers and their remidies. Abbs liquidfilled transformers are manufactured in accordance with the most demanding industry and international standards. Abbyy finereader 12 sprint allows you to merge several documents and either convert them or save them to an image file. Distribution transformer failures follow a bathtub curve.
Page 1 of 12 failures in drytype transformers for offshore applications abstract. It plays important roles both in transmission and in distribution system by transferring the electricity energy. Premature failure of distribution transformers a case study. A distribution transformer or service transformer is a transformer that provides the final voltage transformation in the electric power distribution system, stepping down the voltage used in the distribution lines to the level used by the customer. Practical approach for detection of failure of distribution. Also there is detailed analysis about the consisting of a distribution transformer. Some companies have test fuse tables based on the transformer size and voltage. Finereader engine document and pdf conversion, ocr, icr, omr and barcode recognition. Report on failure of 400220kv33kv, 315mva transformer bhel make at bamnauli substation of delhi transco on 11022008 1.
This proposed idea will detect the fuse failure and intimate the concern persons at that instant using lab view software and messaging system incorporated in distribution transformer. Determination of probability of failure of power transformers. But the key input for estimating distribution transformer energy loss is the transformer load that determines the power factor and energy consumed. Failures in drytype transformers for offshore applications abstract. Distribution transformer is an electrical isolation transformer which convert highvoltage electricity to lower voltage levels acceptable for use in homes and business. For oil filled distribution transformers, the european standard en 504641 includes. Distribution transformersdt losses since transformers are inductive in nature they consume the power with lagging power factor. An analysis of transformer failures, part 2 causes. Based on this definition, statistics on inservice failures and reliability values. Conventional oil testing procedure includes determination of various properties of the transformer oil sample and analyzing the fault. The substation is operating with 1260 mva total transformation. A statistical approach to processing power transformer failure data conference paper pdf available january 2007 with 1,242 reads how we measure reads. Pdf a statistical approach to processing power transformer.
The time delay for clearing this problem is only due to the lack of information. Product literature and application advice were provided by abb. A distribution transformers function is straightforward. Throughout its useful life, a pole mount distribution transformer is exposed to a number of factors which stress it mechanically, electrically. It is emphasized that the object of study are all double winding transformer. The transformer design variability combining above improvements. Distribution transformers always have the potential for. The damage may cause no significant impact, aside from the need to replace the tank, or it could be catastrophic. This article shows that the feasibility of scheduled discard as a failure management strategy mainly depends on the failures probability distribution. Difference between power transformer and distribution. Basics, maintenance, and diagnostics vii contents continued page 4. The two primary enemies of power transformers are transient overvoltages and heat.
Distribution transformers can be installed in ventilated underground or aboveground vaults, away from public access. Actom distribution transformers designs and manufactures a wide range of distribution transformers ranging from 16kva 5000kva. The three methods are conventional oil test, furan derivatives test and markov models criteria. For investigation purpose, we accept ieee standard c57. This procedure sums the joint probability of failure with the reliability function. They provide the link between the distribution network and customers, be they industries, communities or the infrastructure. International organization of scientific research 43 p a g e the distribution transformer is static equipment and is used to either step down or step up the voltage. Transformer failure modes the failure of a power transformer is almost always a catastrophic event that will cause the system to fail. The temperaturedependent thermal resistance expressions can be obtained by combining.
The singlephase distribution transformer consists of a primary winding and a secondary winding wound on a laminated steel core. The risk of a transformer failure is actually twodimensional, the frequency of failure and the severity of failure. There could be many initiators which cause a transformer failure, but those which can potentially lead to catastrophic failure are the following. Depending on the type of distribution system and the vaults exposure to standing water, the transformer may be referred to as vaulttype, network, or submersible. What is distribution transformer, electrical isolation. Transformer overloading and assessment of lossoflife for. Reasons for transformer failures, distribution transformer. This research was initiated to investigate the impact of high power factor on the premature failure of cts. Analysis of cause of failure of distributor transformer. The power transformer cooling system is critical to good transformer health. Transformer design drytype and cast resin, protection methods are being referred and more also included in the specific research document.
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