Power transformer testing tan delta test 02022009 9. The tan delta results, along with other knowledge of the cables history, and possibly other test data like partial discharge, all help to give us some guidance. The dielectric dissipation factor ddftangent delta tg. In this article we are going to discuss in detail about transformer winding tan delta test. This test is also known as the loss tangent or dielectric dissipation factor measurement. Transformer capacitance and tan delta tester the instrument can test the following parameters and display them in figure. Insulation power factor testing of power transformers. The oil tan delta otd is a laboratory instrument, which measures the tan delta, resistivity and relative permittivity of insulating liquids. Tan delta or power factor testing of dry type transformer dear all can anyone please clarify how to connect doble 4100 or omicron cpc 100 to perform tan delta test by mentioning each and every step or can any one post diagram how to perform tan delta test on power transformer. Typical limiting values of sub station electrical equipments. Assessing remnant life of transformer based on furan. Power transformer capacitance and dissipation factor test. Along with this the transformer oil testing is also highly important. These include the chemical and causes of the specific physical properties of the test oils.
Isolate the equipment, apply working grounds to all incoming and outgoing cables and disconnect all incoming and outgoing cables from the transformer bushing terminals. Tan delta is also known as the loss angle or dissipation factor. Winding resistance, turns ratio, bushing tandelta, dga, oil bdv, etc. Tan delta test for power transformers linkedin slideshare. The common basis of all those dielectric diagnostic measurement techniques is that. Tan delta or power factor testing of dry type transformer. Tan delta oil condition monitoring uses advanced, patent protected, technology to tell you the exact condition of any oil to a high degree of accuracy in real time. Tan delta tests are carried out for transformer bushing and for the transformer winding.
Accepting that there are not established, well proven standards for pd or tan delta testing, and both are best used on a. Tan delta, capacitance, dissipation factor measurements and for exciting current test. Capacitance and dissipation factor test procedure two winding drytype transformer step 1. Transformer oil is used in oilfilled electrical power transformers to insulate, stop arcing and corona discharge, and to dissipate the heat of the transformer i. A higher oil conductivity or temperature will cause the tan. Disconnected cables should have sufficient clearance from the switchgear terminals greater that the phase spacing. Pdf investigation of transformer oil exposed to the atmosphere. The latest firmware can be found here vlf sine wave 45 and here vlf sine wave 62. It only shows that the unit has not been processed handeled after processing properly. Testing of insulating oil requires a oil test vessel in addition to the power factor. Oil ducts are distributed between the coils to prevent occurrence of localized hot spots. There are various test required on transformer to conform performance of transformer. Mainly two types of transformer are done by manufacturer before dispatching the transformer mainly 1 type test of transformer and 2 routine test.
I just have one question, is there any standard specifying the tan delta test for specific rating transformers. Tan delta test loss angle test dissipation factor test. Equipment test data permissible limits reference a transformer oil a bdv at the time of first charging 600 kv gap 2. The cable, winding, current transformer, potential transformer, transformer bushing, on which tan delta test or dissipation factor test to be conducted, is first isolated from the system. Insulation diagnostic methods for transformers and bushings. Finally, a test for furans in the oil provides information about the condition of the cellulose. This value is known as the oil quality indexoqin or myers index numbermin. Dissipation factor or simply tan delta of transformer oil courtesy of.
Functionality of the vlf tan delta basic version is accordingly, see figure 3a. In addition some other tests are also carried out by the consumer at site before commissioning and also. Connect the 120 v, 60 hz power through the lamp to the transformer primary, terminals as presented in figure 2 a. These tests give a wider picture of the overall quality of the insulating oil, and will indicate if there is any contamination. In chapter three and four, an extended discussion on the transformer oil properties is made, taking into consideration the eleven most important ones. As the name implies, this test analyzes the type and quantity of gases that are dissolved in the transformer oil. This reliable and accurate information enables automatic notification and scheduling of optimal maintenance intervals based upon actual need. About 4 years back we have also started carrying out sfra sweep frequency response test. Why is tan delta and capacitance test done on transformers. Approx 12 kgs oil test cell this 3 terminal oil test cell is designed for routine and. Tan delta testing of power transformer cr4 discussion thread. The dissipation factor is equal to the tangent of delta, where. Tan delta test for transformer free download as word doc. The power loss is also a very convenient number when checking the accuracy of measurements.
Hence it become important to test them before using it. Capacitance and tan delta set, transformer oil filtration. Tan delta test for transformer capacitor electrical resistance. Capacitance and tan delta test of transformer made in. Tan delta test sets, which come as both standalone and vanmounted systems, are increasingly common components in todays test procedures. Measure with ac test signal, use ohms law to calculate. This test can give an early indication of abnormal behavior of the transformer. Dissolved gasinoil analysis dga testing provides information about the electrical condition of the transformer. Transformer life management oil tan delta megger uk. Also know as power factor and dissipation factor testing, these state of the art instruments give the user a wide range of results for qualitative cable assessments such as degradation and lifetime estimations on mv and hv. Leave the transformer secondary transformer n v a ttr test set h2 x1 h2 x2 c transformer n v a ttr test set h1 x1 x1 h2 b transformer n. Some of the electrical, physical and chemical tests used to assess. Note for test systems vlf sine wave 45 and vlf sine wave 62.
For continuous measurement of oil and winding temperatures, separate meters are used. Multiple frequency insulation test on a healthy transformer influenced by conductive losses influenced by problems that add to polarization. The dissipation factor of new oil should not exceed 0. Tan delta testers are used for the condition assessment of electrical insulation in high voltage apparatus such as transformers, bushings, circuit breakers, cables, lightning arresters, and rotating machinery. In an ideal insulator, as the insulating material which acts as dielectric too, is 100 % pure, the electric current passing through the insulator, only have capac. Transformer oil also known as insulating oil is a special type of oil which has excellent electrical insulating properties and is stable at high temperatures. It is basically the measurement of the leakage current through the oil, which in turn is a measure of the contamination or deterioration of the oil. Tan delta may be defined as the measurement of the cosine of the phase angle or the sine of the loss angle. The measurement and normalisation of dielectric dissipation factor. Testing procedures for power transformer ms excel spreadsheet 23 comments. The delta4310 is a fully automatic 12 kv insulation power factor dissipation factor tan delta test set designed for condition assessment of electrical insulation in high voltage apparatus such as. It is used to test the level of degradation in insulation materials of electrical machines and power cables. It is typically used for test specimen that have small capacitance and as a result the power factor tan delta of the test circuit is rather high.
A very low frequency test voltage is applied across the equipment whose insulation to be tested. Manufacturing, dealing activities in the field of electronics electrical testing and measuring instruments, h v test sets, automatic oil tester, microprocessor based oil test set, microprocessor based oil test set semi automatic, current injection sets, portable relay test sets, transformer ratio meters trm, mumbai, india. Dissolved gasinoil analysis the most important test that can be done on the liquid insulation of a transformer is an annual dissolved gas analysis dga. Calibration equipmenttan deltasubstation testingegyptrol. Megger megger delta4310 power factor tan delta test set. It is a very good practice to standardize on a suitable test report format that will guide the. Very low frequency vlf tan delta testing is a precise and nondestructive method to provide information on the extent of ageing in cable insulation. Buy tan delta testers ireland powerpoint engineering. And also i need all vector group test include this artical. Important note regarding partial discharge versus tan delta. Transformer bushing tan delta test is similar to the ct tan delta test and lnk to the artivle on ct tan delta test is. Megger has developed features of the otd to ensure that productivity levels.
A very lowfrequency test voltage is applied across the equipment whose insulation to be tested. The default test configuration is the ust ungrounded specimen test measurement, in which the transformer. Maintenance and repair of medium power transformers. Data of these test systems can only be imported into the software, if the test systems is equipped with firmware version 3. Capacitance value of tested article cx is in pf or nf, 1nf1,000pf. We have also installed cops constant oil pressure system on most of the transformers, which separates the transformer oil from the atmosphere, preventing gas. Standard practices in transformer oil tangent delta.