Tan delta, also called loss angle or dissipation factor testing, is a diagnostic method of testing cables to determine the quality of the cable insulation. Some ofthe available test methods are listed below. Development of high frequency tan delta measurement method for. The test equipment ctbushing needs to be made potential free, by removing the jumpers. E the storage modulus is the elastic component and describes the samples stiffness. Us20030160602a1 power factortan delta testing of high.
Field application offline test that uses a low voltage, high frequency pulse generator. Vlf testing tan delta loss factor measurement partial discharge. High levels of environmental moisture, elevated temperature, and chemicals or pollution may require more frequent testing. Tan delta testing is a diagnostic method of testing cables to determine the quality of the cable insulation.
E the loss modulus is the viscous component and is related to the samples. When the cable system passes the leakage current test withstand test, the test voltage is regulated to zero and the cable system and test set are discharged and grounded. Standard test method for glass transition temperature dma. Tan delta test for transformer capacitor electrical resistance. It is intended to detect deterioration of the system and to check the serviceability so that suitable maintenance procedures can be initiated. Sinewave test set accessories may be available enabling dissipation factor tan delta and or partial discharge diagnostic capability. This reduces the costs for training and transport, and cuts down testing time. Megger testing 6 time domain reflectometry testing tdr specific test methods may be more applicable to one category, while some test methods may be applied to both categories. The ieee recognizes the sine wave output as advantageous and. Tan delta is also known as the loss angle or dissipation factor.
The testing frequency depends on the rate of change of the insulation quality, history of past failures, environmental conditions, etc. This is a global test of the cable, providing the condition from end to end. The simplest vlf testing technique to assess the quality of electrical insulation is the withstand test, in which the cable is subjected to a test voltage significantly. Very low frequency vlf tan delta testing is a precise and nondestructive method to provide information on the extent of ageing in cable insulation. The power loss is also a very convenient number when checking the accuracy of measurements. During the test cables are subjected to a test voltage significantly higher than what they experience during normal operating conditions. Dta is available in a basic or professional version depending. Power factor dissipation factor tan delta tan delta, also called loss angle or dissipation factor df testing, is a diagnostic method of testing cables to determine the quality of the insulation. The tan delta controller unit takes measurement of tan delta values. Data of these test systems can only be imported into the software, if the test systems is equipped with firmware version 3. Transformer bushing tan delta test is similar to the ct tan delta test and lnk to the artivle on ct tan delta test is. Cp td1215 innovative power system testing solutions.
Tan delta, also called loss angle or dissipation factor testing, is a diagnostic method of. Tan delta measurement used as a diagnostic ratio between loss current and charging current loss current increases as cable ages increasing tan delta angle absolute tan delta, tipup and stability values are derived ieee 400 2012 omnibus ieee guide for field testing and evaluation of the insulation. When the cable system passes the leakage current test withstand test, the test voltage is regulated to zero and the cable system and test set. Tan delta tests are carried out for transformer bushing and for the transformer winding.
You can operate the cpc 100 via the integrated front panel, or by using. 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. Tan delta testing can be performed during the manufacturing process. The copper is a conduit for the stator winding current. Choosing the right parameter in the tandelta pf test card. It also gives an idea of the aging process in the cable. This is done to try to predict the remaining life expectancy and in order to prioritize cable replacement andor injection. It is also useful for determining what other tests may be worthwhile. The patented cpc 100 primary injection test system replaces several individual testing devices. The following sections of the ansineta standard for acceptance testing specifications for. Simultaneous partial discharge and tan delta measurements hv.
Tan delta testing is performed with the cable offline. During the test, it is essential to apply test voltage at a very low frequency. Why tan delta test is required a pure insulator when is connected across line and earth, it behaves as a capacitor. Why tan delta test of ct, pt and bushing is required. How to interpret tan delta test result in a rotating machine 03162017 9. Doble test assistant software doble engineering company. The test voltage is regulated to the test voltage level of 3 u. In this video you will learn about means to measure the quality of the insulation of power transformers and bushings, such as powe. Using a vlf as the voltage source and a separate divider to make the measurements, the voltage is raised while measuring the tan delta of the cable. Measurement of power factor to diagnose the condition of high powered standoff insulators, which include a roll of insulating material carrying an intermediate layer of conductor between layers of the insulating material around a central hv conductor in a hollow insulator body, is accomplished while the power system is subject to full voltage.
Tan delta test for transformer free download as word doc. If the insulation of a cable is free from defects like trees, moisture and air pockets, etc. It is used to test the level of degradation in insulation materials of electrical machines and power cables. It is a diagnostic test, meaning it is not a vlf ac withstand test where the risk of cable failure is high. 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. Standard for acceptance testing specifications for. The test is typically performed over a range of test voltages from 0. The details of the entire procedure are given in the astm d 924 standard and are only briefly mentioned here. Other than very low frequency power test set, other power source cannot work for applying specified high voltage for measurement of tan delta, capacitance and ac leakage current.
How to interpret tan delta test result in a rotating machine. Vlf breakdown voltage of highly aged xlpe cables in weibull format. Dta is a trusted and intelligent software platform that takes asset testing and data analysis to the next level. Tan delta is a a diagnostic test conducted on the insulation of cables and winding. Combining vlf cable testing and vlf tan delta diagnostics can avoid these limitations. A vlf ac test instrument provides the test voltage to the cable while the td device records the results. In an ideal insulator, as the insulating material which acts as dielectric. Drytype transformer testing introduction the primary concern with all transformers and also the key indicator of life expectancy is the. A loss angle analyzer is connected with tan delta measuring unit to compare the tan delta values at normal voltage and higher voltages and analyze the results. Hundreds of standards including cable testing standards.
The tan delta test is a procedure a utility can use to check on the quality of insulation in medium to high voltage cable. Vlf tan delta and withstand testing of electrical power cables 6 maintenance test a field test made during the operating life of a cable system. Tan delta test loss angle test dissipation factor test. Pdf measurement of the dielectric performance of an instrument. Dielectric loss angle tests, also called dissipation factor, power factor or tan delta tests, determine the. Tan delta point is to be disconnected from the earth. Typical voltages supplied by tan delta test sets range from 30v to 60kv, but can be even greater when used as a bridge with an external supply such as a cds.
Doble test assistant software is your comprehensive software tool for the collection, analysis and management of test results for the doble mseries family of instruments. In this study, the capacity, tan delta and dielectric loss of an ivt are measured for different voltage levels and frequency values. Relationship between capacitive and resistive currents the ratio of the two currents i r i c is the tangent of the angle. By opening the template file, the cpc editor appears with the test card. Testing of hv cables supplementary information page 1 of 24 reference sp0407r02 ver 2 ergon energy corporation limited abn 50 087 646 062 1.
With td testing, cables can be rated as highly, moderately, or slightly degraded. Measure with ac test signal, use ohms law to calculate. Vlf tan delta and withstand testing of electrical power cables. Introduction this reference is intended to give a basic overview of insulating materials that can be used during high voltage withstand testing, in particular cable testing. Conclusion a new set of well conceived testing standards has been developed in response to changes in cable technology in recent years. Insulation power factor testing of power transformers. Test description measures changes in the cable impedance as a function of circuit length by observing the pattern of wave reflections. Megger testing 6 time domain reflectometry testing tdr specific test methods may be more applicable to one category, while some test methods may be applied to. Netaworld online versus offline partial discharge testing for cable assessment 65 figure 1. In this article we are going to discuss in detail about transformer winding tan delta test. A technician can use this test in a diagnostic evaluation of a cable that is not performing properly.
If a cable is perfect, it behaves like a capacitor where there is a phase. Very low frequency vlf dielectric withstand voltage 3. It is used to measure the deterioration in the cable. Therefore, the cpc 100 is the ideal test set for substation asset commissioning and maintenance. Standards for high voltage field testing for hv cables. This paper discusses the dissipation factor measurements that can be carried out on the insulation of power transformers during routine maintenance procedures. The cp td1215 is an optional module for capacitance and power factordissipation factor tan delta measurements on highvoltage assets. During the test, it is essential to apply test voltage at a. Dissipation power factor and capacitance measurement on. This increases the sensitivity of the test and helps you to better assess the insulation condition and detect defects at an early stage.
Setting up the kit the kit consists of mainly of 2 units. Today, there are more field test methods available. In uence of external factors on results of bushing tan. 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. The software can be operated on any windows platform. Used to identify locations of accessories, faults, etc. Very low frequency vlf tan delta testing is a precise and nondestructive method to provide information on the extent of ageing in cable.