Oil testing allows the operator to determine the equipments operating efficiency, conditions and the possibility of future malfunctions. Now lets move to, transformer oil purification procedure. The iec standard procedures used to test the insulating oil would introduce as. So for ensuring proper performance of electrical power transformer, voltage and turn ratio test of transformer one of the important tests. Transformer oil maintenance electric energy online. Potential transformers pts or voltage transformers vts pts or vts are the most common device used. Transformer oil testing quick, simple and onsite b2hv. Specific transformer oil test method availability will vary depending upon location. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Transformer oil testing is a proven loss prevention technique that should be a part of any condition based predictive maintenance program. Periodic execution of oil tests also makes sense from an economic point of view, as. All of these oil types can be tested for dielectric breakdown voltage and tested with megger ots range test sets. Sep 24, 2017 with the help of transformer oil testing kit we can test transformer oil learn the process step by step.
There are many mineral oil filled transformers that have been in continuous use for more than 50 years. The lower the resulting breakdown voltage, the poorer the quality of the transformer oil. Identifies various gas ppm levels that are present in transformer insulating oil. These devices use standard transformer theory with 23 windings one primary with one or two secondary windings with a magnetic connection via an iron core. Regular sampling and testing of insulation oil taken from transformers is a valuable technique in a preventative maintenance pr ogram.
This amounts to a rigorous examination of the transformer intended to. Because these generate a lot of heat that must be removed, they need to be insulated and they have to resist sparking, the physical and chemical properties of certain oils make them ideal for use in transformers and capacitors. Routine testing of transformer oils and insulating oils on a regular schedule is an accepted industry. For oils in service, an increasing or high color number is an indication of contamination, deterioration, or both. The different insulating materials have different dielectric strength. Verify correct operation of transformer withdrawal mechanism and grounding operation. Testing the condition and quality of transformer insulating oil provides data showing the actual condition of the transformer, and its remaining lifetime. 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. Standard for acceptance testing specifications for electrical. Breakdown voltage bdv testing of transformer oil youtube.
Jan 23, 2017 breakdown voltage bdv testing of transformer oil. Before proceding with transformer measurements the test engineer will become familiar with the safety rules of section 2. Testing of oil in the field is typically limited to testing at whatever temperature. A primary part of commissioning a transformer involves testing it after its installation in the field. Transformer oil testing by robert turcotte, manager, electrical loss control the hartford steam boiler inspection and insurance company the value of transformer oil testing transformer oil testing is a proven loss prevention technique which should be a part. For inservice equipment in particular, there are many test techniques for evaluating the condition of the insulating oil. This early warning system can allow management to identify maintenance priorities, plan work assignment schedules, and order necessary parts and materials. Once power transformer is charged and commissioned, transformer oil becomes a key element to.
The automatically generated report of the transformer oil testing sequence is available as a pdf version and is stored to the internal memory. Insulation power factor testing of power transformers. The transformer oil is used in the transformer for insulation as well as for cooling purpose. Routine tests and type tests of transformers electrical4u. This test also performed as a routine test of transformer. Tests at these two temperatures provides much more insight into the characteristics and quality of the oil encountered.
In this book we have laid down important aspects on transformer testing in order to enhance the understanding of the testing procedures and its outcome. The american society for testing and materials astm is the standard reference body used by. There are three basic styles used to transformer system voltages to control voltages. Taking oil sample from power transformers dissolved gases astm d 3612, iec 60567, dissolved water astm d 1533, iec 60814 the following is one of the procedures to collect transformer oil sample. Take a microlitre of oil for sampling and placed the oil in a chromatographic separation using column by using a mobile phase. The transformer installation position should be such that the breather, oil level indicator, rating and diagram plate, dial thermometers etc. Sunbelt transformer liquidfilled transformer instruction and maintenance manual 3 4 internal inspection note. Remove shield from outlet sampling point 6 of a transformer. With transformer oil this is done through testing of the oil. The analytes remain on the stationary phase of the column with varying degrees of force due to the polar interaction. The following sections of the ansineta standard for acceptance testing specifications for.
This ms excel spreadsheet is actually detailed instruction for each procedure necessary for correct testing of power transformer. Initial testing will establish a base line and annual testing will plot any changes happening internally in the transformer. Testing sequences and procedures are defined by various international. Furan analysis and of testing of transformer oil powerlink.
Pdf significance of transformer oil testing researchgate. It evolved from the simple gonogo verdict into a sophisticated segment within transformer manufacturing. The insulating material should sustain the voltage up to its dielectric strength. Oil tests in the shop or laboratory would be carried out at room temperature 20o c as well as at an elevated temperature of 90o or 100o c. Transformer testing has developed considerably over the past years.
Neta defines the standards by which electrical equipment is deemed safe and reliable. Breakdown voltage of the transformer oils under certain conditions. C the transformer should be tapped up as necessary with clean transformer oil. Regular sampling and testing of insulation oil taken from transformers is a valuable. If a proactive approach is adopted based on the condition of the transformer oil, the life of the transformer can be extended. May 10, 20 so transformer ratio test is an essential type test of transformer. The transformer oil is filled in the vessel of the testing device.
Standard for acceptance testing specifications for. International standards define the test sequence and procedure of such a test. When transformer is to be filled or topped off in the field, they must be filled under vacuum according to specific instruction. Despite the apparent superiority of naphthabased oil, paraffin oil remains the most commonly used type of oil in transformers worldwide. Testing of power transformers seems like a similar experience. New oil should have a minimum dielectric strength of 35 kv by astm methods of testing. Transformer oil test methods include astm, bs,and other recognized transformer oil analysis testing procedures. To prove that the transformer meets customers specifications and design expectations, the transformer has to go through different testing procedures in manufacturer premises. In this book we have laid down important aspects on transformer. It should also be possible to have access to the operating mechanisms of the on load tap changeroff circuit tap switch, marshalling box etc. Only competent and qualified should open a sealed transformer. The gas space above the oil is filled with nitrogen. Learn what transformer oil is, how to test transformer oil and the different types.
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. Practice procedure of transformer oil sampling iec 60475 procedure of oil sampling in aluminum bottle the aluminum bottle is used for oil analysis in general and for analysis of compounds which are sensitive to light such as peroxide and furfural. The megger guide to insulating oil dielectric breakdown testing. When predictive maintenance transformer and oil tests has disclosed a serious problem of moisture, combustible gas andor oil decay products, and on site purification is the chosen procedure the following steps are suggested. The international electrical testing association neta is an accredited standards developer for the american national standards institute ansi. The ac hv test value should not surpass 75% of the factory test value. Transformer oil testing by robert turcotte, manager, electrical loss control the hartford steam boiler inspection and insurance company the value of transformer oil testing transformer oil testing is a proven loss prevention technique which should be a part of any conditionbased predictive maintenance program. The are distinct advantages of testing and analyzing transformer oil before starting your electric power equipment and during scheduled maintenance events. An internal inspection is necessary only if internal damage is suspected because of external indications of rough handling. These tests are done mainly in a prototype unit not in all manufactured units in a lot. Power transformer testing procedures and schemes eep.
Basics, maintenance, and diagnostics ix contents continued page 6. I and testing of oil as per specified standard is mandatory. Transformer oil, a type of insulating and cooling oil used in transformers and other electrical equipment, needs to be tested periodically to ensure that it is still fit for purpose. Astm d117 18 standard guide for sampling, test methods, and. Bluetooth connection as means of communication with the instruments a usb flash drive interface and a bluetooth connection is offered.
Mineral oil is the most common insulating fluid and has been in use since the late 19th century. Inspect transformer and parts for shipping damage and moisture. 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. Transformer oil purification filtration processprocedure. Transformer testing commissioning, routine, diagnostic. Transformer is one of the main asset in the electrical power industry which needs to be maintained for guaranteed uninterrupted power transmission in order to get assured revenue benefits. To assess the insulating property of dielectric transformer oil, a sample of the transformer oil is taken and its breakdown voltage is measured. To ensure that the product is fit for its intended use standards iec standards iec 60076 part 1 part 14 specification for transformers ieee. Testing consists of measuring breakdown voltage and. Through proper testing, the transformers lifespan is increased, reducing the need to pay for replacement. Testing standards and procedures are defined by various. Development of an ongoing maintenance program will help prevent costly failures.
Testing potential transformers relay testing training. The procedure of the transformer ratio test is simple. The megger guide to insulating oil dielectric breakdown. One nettlesome aspect of electrical equipment that runs 24 hours a day, seven days a week is the need for continual testing and maintenance to ensure both safety and proper. The dielectric breakdown voltage is measured by applying a voltage between two electrodes under the oil.
Power transformer testing procedures and schemes photo credit. It is a good idea to remove all as a safety precaution to prevent backfeeding dangerous voltages into the system during testing. The indicator generally shows the cold level when the oil is at a temperature of about 25 deg. Oil testing consists of measuring the breakdown voltage, and other chemical and physical properties of the oil, either through portable test equipment or in a laboratory. Some transformer tests are carried out for confirming the basic design expectation of that transformer. Neta is the leading source of specifications, procedures, testing, and requirements. If the oil level drops appreciably over a short period, the tank should be checked for leaks. Testing sequences and procedures are defined by various international standards, many of them set by astm. Transformer oil is a required addition to electrical transformers. When the pt is withdrawn ensure that there is no longer any connection with the primary electrical system. Astm d117 18 standard guide for sampling, test methods. Following is an approximate sequence for transformer testing.
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