In ghana, distribution transformers mostly step down voltages from either 33kv or 11kv on an investigation into protection integrity of distribution transformers a case study. Sep 08, 2015 transformer failure modes the failure of a power transformer is almost always a catastrophic event that will cause the system to fail. Estimation of distribution transformer losses in feeder circuit v. Analysis of failure statistics and history test record for. The different types of transformer are step up and step down transformer, power transformer, distribution transformer, instrument transformer comprising current and. Practical approach for detection of failure of distribution transformers and their remidies. 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. Pdf diagnosing failed distribution transformers using. In distribution side transformers there are commonly two. A statistical approach to processing power transformer. Like all electrical devices faults also happen in the transformers which cause failures 1. Reference 1 many district transformer designs already meet the doe requirements.
As a comparison the transformer failure rate ranges suggested in reference bollen 1993 are given below. The two primary enemies of power transformers are transient overvoltages and heat. The quantitative fault tree analysis resulted the rankings of quantitative contribution of. A distribution network load distribution model is proposed which takes distribution network reliability, transformer economic operation and.
Distribution transformer is an electrical isolation transformer which convert highvoltage electricity to lower voltage levels acceptable for use in homes and business. State 2 shows the status that windings failure leads to removal of the transformer from service. Not replacing of old oil over long time or its deficiency due to leakage causes internal overflashing. Intelligent energy projects christian osorio, nandan sawant 1. Sep 30, 2015 failure to assess epoxy insulation as part of your experts fault tree transformer failure analysis may be like optimus prime failing to detect megatron came back to life in the transformer movies. Padmounted transformers are used with underground systems. It is emphasized that the object of study are all double winding transformer. Offline smps failure modes pwm switchers and dcdc converters 5 this is the common failure mode for a bipolar transistor pn junction during a shortload event. Performance test of faulty distribution transformers along. Analysis of power transf failure in trans utilities 15.
In between, severe overloading or lightning cause most transformer failures. The premature failure rate of distribution transformers is above 25% in some of the regions of the state of madhya pradesh m. The transformers have laminated steel cores in the middle surrounded by the transformer windings. Data collected over the period 20112015 on the distribution network were simulated on etap software using the newton. A distribution transformers function is straightforward. Reliability model of power transformer with onan cooling. Major losses involving large oilcooled transformers continue to occur on a. Reliability model of power transformer with onan cooling 105 shown in fig.
Fault in the core directly affect the transformer windings, causing faults in them. Bayesian analysis of power transformer failure rate based on condition monitoring information t pdf created with pdffactory trial version 2. Paper 3 predicting transformer lifetime using survival. The advent of csp technology has encouraged progressive manifactures to go in for high performance distribution transforms. An international analysis of transformer failures, part 2. Merges the attributes andor geometry of one set of features onto another set of features, based on matching key attribute values and expressions. Transformer lifetime prediction stanford university. However, the various techniques for internal fault identification include refusing, and if the transformer is faulted a fuse operation itself is a dramatic event for the line worker, just less so than a full transformer failure. Some of the most commonly occurring failures of the transformer and their causes are listed below. Bayesian analysis of power transformer failure rate based on. Transformer overloading and assessment of lossoflife for liquidfilled transformers.
The cores of the transformers are laminated to reduce eddycurrent. As you are aware, the distribution sector has a large number of distribution transformers of several capacities. In the event of failure of distribution transformer, apart from the loss of capital to the utility, the consumer suffers due to inconvenience caused by the interruption of power supply. For the failures reported, the leading cause of transformer failures is insulation failure. What is distribution transformer, electrical isolation. An analysis of transformer failures, part 2 causes. Estimation of distribution transformer losses in feeder circuit. Analysis of transformer loadings and failure rate in. Transformers plays a very important role in the power system. Again, in the event of this illegal connection of power from the distribution low tension lines due to power failure or outage from one streetroad tend to cause under voltage or over voltage as the case may be what will be the result. This example will look at using the featuremerger transformer. Distribution system component failure rates and repair times. Bayesian analysis of power transformer failure rate.
The different failure modes that can take place in a power transformer can have different origins. Reliability and vulnerability of transformers for electricity. This research was initiated to investigate the impact of high power factor on the premature failure of cts. 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.
Distribution transformer installed stocks growth rate 6. Analysis of transformer loadings and failure rate in onitsha. Offline smps failure modes pwm switchers and dcdc converters. Predicting transformer lifetime using survival analysis and. Disclaimer the authors have done their best in providing an overview of the available information sources, published during the period 19932003, on distribution system component failure. Distribution transformer failures follow a bathtub curve. 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. Causes of transformer failures between 1991 and 2010 as a percentage of. An investigation into protection integrity of distribution. Transformer failure modes the failure of a power transformer is almost always a catastrophic event that will cause the system to fail.
An external fusecutout combination is mounted between the distribution primary and the conventional transformer. By means of statistical failure analysis the ageing processes related to the ages of the transformers can be shown. The premature failure rate of distribution transformers is above 25% in some of the regions of. The substation is operating with 1260 mva total transformation. An analysis of international transformer failures, part 2 introduction. Any failure of these transformers is bound to cause great inconvenience to the consumers and huge financial losses to the utilities. An analysis of international transformer failures, part 2. Minimize the failures of distribution transformer seminar. Report on failure of 400220kv33kv, 315mva transformer bhel make at bamnauli substation of delhi transco on 11022008 1. The function of the core is to concentrate the magnetic flux. Failure of distribution transformers causes capital loss and loss of revenue to the nation. Transformer losses and impact on first cost background by doe mandate, effective january, 2010 all oilfilled distribution transformers manufactured in the u. State 1 is related to the condition in which no fault occurs in windings. 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.
State 3 demonstrates the condition that windings have fault but by reducing the. Bayesian update condition monitoring information assumed probabilistic model. In the uk this was, until january 1995, 415 v threephase and 240 v phase to neutral. Reports in eskom distribution indicated that a number of cts from. Key international mergers and acquisitions of power equipment.
Determination of probability of failure of power transformers. The invention of a practical efficient transformer made ac power distribution feasible. Data collected over the period 20112015 on the distribution network were simulated on etap software using the newtonraphson nr. Reasons for transformer failures, distribution transformer. That is, the highest failure rates are in the first few years of service and then decline. 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. Problem statement the costs of blackouts can be astronomical. Distribution system component failure rates and repair. This study investigated transformer loadings and failure rate in the onitsha electricity distribution network by using the electrical transient analysis program etap software 12. Power input to a transformer is not all delivered to the secondary load. Indeed, it will surely cause a transformer failure in due course. A distribution transformer s function is straightforward. The sustained failure rates for mvmv transformers published during the recent decade indicate a variation of the average transformer failure rates in the range 0. Types of transformer there are various types of transformer used in the electrical power system for different purposes, like generation, distribution and transmission and utilization of electrical power.
Types of transformer different types of transformer. A practical method for risk assessment in power transformer fleets1. 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. Information about fist transformers,general transformer design drytype and cast resin, protection methods are being referred and more also included in the specific research document. Estimation of distribution transformer losses in feeder. Submitted in partial fulfillment of the requirements for the degree of doctor of philosophy of kyoto university. 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. During this overcurrent, the junction depletion regions grow so large that the majority carriers. Practical approach for detection of failure of distribution. Minimize the failures of distribution transformer seminar report pdf ppt download abstract. If it is a high frequency transformer then the risk would primarily.
Bayesian analysis of power transformer failure rate based. Determination of probability of failure of power transformers using statistical analysis keri pickster a dissertation submitted to the faculty of engineering and the built environment, university of the witwatersrand, johannesburg, in ful lment of the requirements for the degree of master of science in engineering. Transformer overloading and assessment of lossoflife for. K katti international journal of computer and electrical engineering, vol. Distribution transformer is an essential link in the distribution system.
This paper will address the transformer failure statistics over the last 5 years, the. Distribution network load distribution strategy considering the economy of parallel transformers is put forward in this paper. Failure mode distribution of transformers in thailand. Failures in drytype transformers for offshore applications abstract. There could be many initiators which cause a transformer failure, but those which can potentially lead to catastrophic failure are the following. Failure to assess epoxy insulation as part of your experts fault tree transformer failure analysis may be like optimus prime failing to detect megatron came back to life in the transformer movies. The high current seen at the device junction displays a typical failure mechanism. It is thus very important to avoid transformer failure. Pdf a statistical approach to processing power transformer. This category includes inadequate or defective installation, insulation deterioration, and short. In our previous discussion of a fiveyear international study of loss trends for transformer failures, we concluded that insulation failure was the leading cause. Power supply utility also suffers due to loss of revenue for supply outage period.
Analysis of failure statistics and history test record for power transformer maintenance ekkachai chaidee, thanapong suwanasri and cattareeya adsoongnoen abstract in this paper, power transformer is selected as pilot equipment for maintenance improvement analysis because of its cost and failure consequence. Page 1 of 12 failures in drytype transformers for offshore applications abstract. Title failure analysis of power transformer based on fault. Is there a way of merging a list of pdf files to a multipage pdf file. If ageing can be denoted as the main cause for failure, the question then becomes to what extent ageing occurs. Failures increase later, towards the normal end of service life. Reliability and vulnerability of transformers for electricity transmission and distribution keywords critical infrastructure, transformer, reliability, ageing, blackouts abstract in the last years the failure frequency of transformers increased, e. Tertiary winding terminals taken out of the tank of transformer to avoid short circuiting. A statistical approach to processing power transformer failure data conference paper pdf available january 2007 with 1,242 reads how we measure reads. Reports in eskom distribution indicated that a number of cts from one manufacturer were exceeding the specified insulation power factor value. Powweerr rt rraannssffoormmeer eennddoofflliiffee mooddee llliinngg l innkk inngg issttaattisstticcss wwiitthh phhyyssiiccaall aaggeeiinngg a thesis submitted to the university of manchester for the degree of doctor of philosophy in the faculty of engineering and physical sciences. Jul 29, 2014 it completely depends on the design it lands in. Transformer and cable failure rates published during the recent decade indicate somewhat lower values than the suggested values in reference bollen 1993. Power transformer lifecycle cost reduction glenn swift tom molinski alpha power technologies manitoba hydro winnipeg, canada winnipeg, canada abstract using longterm thermal lossoflife analysis, probability of failure analysis, and economic analysis, it is shown that power transformers may be kept in service longer than is the.
The relay is normally wired to start fans andor oil pumps at the low temperature, alarm at the middle temperature, and trip breakers to remove the transformer from service at the high temperature setting, transformers which. The risk of a transformer failure is actually twodimensional, the frequency of failure and the severity of failure. This paper evaluates the uptime distribution or failure mode distribution of 22 and 33 kv distribution transformers of the provincial electricity authority of thailand pea. In india, the failure rate of distribution transformers is very high, around. There are multiple ways of joining data together using fme. Again, in the event of this illegal connection of power from the distribution low tension lines due to power failure or outage from one streetroad tend to cause under voltage or over voltage as the case may be. 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.