Transformer testing method pdf

Know the condition of your transformer to get the most out of your asset. Staffing resources adequate staffing resources with the competencies to safely. Namely, if testing is based on injecting only one sequence current component at the time on both ct inputs of the transformer differential protection, simple testing procedures can be derived, which are more intuitive, less complex and straightforward than existing phasewise testing procedures. The preference is that all large power transformers 1 mva be tested with ttr test set. This early warning system can allow maintenance management to identify maintenance priorities, plan work assignment schedules, arrange for outside service, and order necessary parts and materials. As power transformer is highly expensive as well as important part of distribution system. Here the ratio and phase angle of the test transformer x are determined, in terms of that of a standard transformer s having the same.

The following sections of the ansineta standard for acceptance testing specifications for. An electrical power transformer has to go through a number of transformer testing procedures for confirming its specifications and performances. Regular sampling and testing of insulation oil taken from transformers is a valuable technique in a preventative maintenance pr ogram. The type and routine test are very important for transformer. Ensure the ct is connected to system properly in all respect primary and secondary. Pdf easy method for testing transformer differential relays. The test and assessment of transformers is a complicated task.

These tests are done mainly in a prototype unit not in all manufactured units in a lot. The amperage rating for your transformer fuse may be labeled on the transformer. In this article, you will learn different types of transformer testing methods, test setup, and their acceptance criteria. When ac hipot tests are used for routine maintenance, the power transformer can be examined at. By means of cascading, the size of the transformer and the insulation bushing. This purpose of this method statement is to apply a proper way of installing or placing the power transformer in the project. The ac hv test value should not surpass 75% of the factory test value. If the transformer is new, the resistance test also serves as a verification of the manufacturers work. To confirm the physical condition and electrical characteristics of current transformer installed in the installation. As it checks the quality of material used and the procedure of transformer manufacturing hence provide us details of life of transformer, the transformer behaviour on different faults. Ab testing, split testing, or bucket testing is a method of marketing testing by which a baseline control sample is compared to a variety of singlevariable test samples in order to improve. Measurement shall be carried out with direct current dc by the voltage drop method or the bridge method as specified in the manufacturer approved power transformer testing procedure.

Transformer installation method statement electrical. Testing of current transformers, voltage transformers or auxiliary transformers internal to the power transformer are not included in this swp. To prove that the transformer meets customers specifications and design expectations, the transformer has to go through different testing procedures in manufacturer premises. A test set operator connects the leads, pushes the buttons, and records the results.

Transformer winding resistance measurement is carried out to calculate the i 2 r losses and to calculate winding temperature at the end of a temperature rise test. If a proactive approach is adopted based on the condition of the transformer oil, the life of the transformer can be extended. If the reading is above the amperage rating for the transformer, the circuit is drawing too much power. Partial discharges in transformers are typically measured by applying a prespecified voltage to the transformer windings and measuring induced charges via a. Transformer will be moved by crane using lifting lugs as per manufacturers, recommendation and shall be positioned on transformer base in plant yard. Test this by hooking up the secondary to its circuit and using your dmm to test the secondary lines. An established test method is astm method d3455 for oil compatibility. Silsbees method is a comparison method used for current transformers testing. Pdf transformer testing type test and routine test of. Many of the details of a complete and effective testing procedure can be obtained from this source.

Testing power transformers highvoltage transformers are some of the most important and expensive pieces of. Put your ohmmeter on its lowest scale and after removing the plastic sheaths from the conductors, touch its leads together to verify that it is ready for testing. Power transformer testing the advantage of this method is the simplicity of the test. Silsbee contents t page introduction 317 generalprinciples 318 nullmethod 321 deflectionmethod 325 experimentalresults. Medium and high voltage eis transformer testing with ieee. To test a transformer, however, you will need to disconnect it from the circuit before doing anything else. Section 7 of the ansineta standard for acceptance testing specifications for electrical power equipment and systems may be reproduced and used on a cut and paste basis for the particular type of equipment to be tested. If a very high voltage is required, the transformer is usually build up in stages by cascading. Back to the basics current testing valence electrical. How to use an ohmmeter to test an ac transformer sciencing. Transformer will be moved over rails and brought to the position as indicated in the drawing, after installation of wheels at base.

Aa an ansi american national standard institute cooling class designation indicating open, naturaldraft ventilated transformer construction, usually for drytype transformers air cooled a transformer that is cooled by the natural circulation of air around, or through, the core and coils ambient noise level the existing or inherent sound level of the area surrounding the. Transformer bushing cts should be tested using the current ratio test method before the transformer has been completely assembled. Diagnostic testing and monitoring will help you to determine. The scope of this work is to deliver the material and including the installation as well as the testing and commissioning. This method statement will give a brief steps to be carried out for testing and pre commissioning of transformers. Turnsratio test results should not deviate more than onehalf percent from either the adjacent coils or the calculated ratio. When ac hipot tests are used for routine maintenance, the power transformer can be examined at rated voltage for 3 min instead of testing at 65% of factory test voltage. Testing and diagnostics of power transformers brochure 4. Optical measurements of the arc movement may be difficult to accomplish without changing the switchgear device. Transformer ct testing as test equipment becomes more sophisticated with better features and accuracy, we risk turning our field personnel into test set operators instead of skilled field service technicians. Different cooling methods of transformers are air natural, air blast, oil natural. The arrangement for this method is shown schematically in below figure. It is obvious that transformer needs a cooling system. Some transformer tests are carried out for confirming the basic design expectation of that transformer.

Pdf transformer is a static device which transforms a. This ms excel spreadsheet is actually detailed instruction for each procedure necessary for correct testing of power transformer. It is also done at site to ensure healthiness of a transformer that is to check loose connections, broken strands of conductor, high contact resistance in tap changers, high. Testing of transformer or insulating oil transformer oil, a type of insulating and cooling oil used. This method builds upon a comprehensive condition assessment program based on ieee historical data, and is designed to systematically identify changes in transformer condition. Finally punch the cable lugs on each core terminal with the help of hydraulic crimping tool and insulate the lugs with insulation tape, tie the cable with supporting clamp and gland the cable in the transformer cable termination box, connect the cable to the bushing and fix the bolt tightly using torque wrench.

Build your own current limiter for protection when repairing and testing electronic equipment duration. Method statement for installation of 33kv power transformer. Transformer testing has developed considerably over the past years. Inspect transformer and parts for shipping damage and moisture. Method statement for installation of transformers safe. In this section we will insist in the electric detection methods although we will also. Astm d117 18 standard guide for sampling, test methods. From the analysis of the equivalent circuit one can determine the electrical parameters. The voltage method should be regarded as the last alternative.

Partial discharge testing can detect the presence and location of partial discharge activity in a transformer. Transformer oil testing is a proven loss prevention technique which should be a part of any condition based predictive maintenance program. Timeresistance testing method this method is fairly independent of temperature and often. Basics, maintenance, and diagnostics xi contents continued page 9. The typical excitation current test data pattern for a threelegged core transformer is two similar current readings and one lower current reading. When testing a transformer for turns ratio, the connections are determined by matching parallel vectors. This will prevent inaccurate readings and ensure your own safety. Standard for acceptance testing specifications for. But if the temperature rise of the transformer is required, then test method is. The standard megger testing equipment is used, the line terminal of which is connected to the winding or core bolt under test. While online diagnostic systems and computerized testing methods are very helpful, they are not a substitute for sound.

Understanding insulation resistance testing pdf 0712 technical assistance 800 34391. It is carried out as a type test as well as routine test. Testing of power transformers seems like a similar experience. Ppt transformer tests powerpoint presentation free to. High voltage testing 149 the high voltage is applied across the device under test by means of a transformer. The objective of testing is to ensure quality to ensure that the products manufactured have met the requirements of customer specificationstandard to prevent accidents which may occur if a failed product is put into service. To ensure that the product is fit for its intended use standards iec standards iec 60076 part 1 part 14 specification for transformers ieee. Following is an approximate sequence for transformer testing.

In this book we have laid down important aspects on transformer. Hipot test is typically used for acceptance testing or after transformer repair testing. Industrial tests transformer life analysis program can reduce the risk of transformer failure and. It evolved from the simple gonogo verdict into a sophisticated segment within transformer manufacturing.

C electrical power from one voltage to another voltage keeping the frequency same by. Easy method for testing transformer differential relays conference paper pdf available september 2009 with 14,376 reads how we measure reads. This test method assumes the behavior of the oil is already known and the selection of a single temperature is based on the known behavior of the oil. Morgan tm schaffer transformers the inside view transformer tests oil tests and online monitoring can increase transformer life expectancy by. Current transformer working current transformer testing. Cts should be tested before they are mounted on the transformer. Making a wellinformed choice in equipment for transformer testing is an important step towards ultimately improving transformer life management decisions. The installation and testing of the transformer verifies its. Field testing of a power transformer before putting into service 50mva. What is the megger test procedure for transformers. The voltage ratio shall be measured on each tapping and verified aginst manufacturer approved power transformer testing procedure. If this heat is not dissipated properly, the excess temperature in transformer may cause serious problems like insulation failure.