Measuring the polarity and turn ratio of a transformer winding assures that the connections. This analog meter has manual range selection for flexibility and ease of use. Ttr300 series threephase transformer turns ratio test set. For all practical purposes, when the transformer is on open circuit, its voltage and turns ratios may be considered equal. The pattr03a generates and outputs an excitation test voltage to the transformer s three primary windings. Testing power transformers highvoltage transformers are some of the most important and expensive pieces of. Note that the order of the numbers when expressing a transformers turns ratio value is very important as the turns ratio 3. A transformer expert looked at the test data for us and did the folowing analysis. The induced secondary voltage is sensed and the transformer turns ratio is calculated. The ttr300 series also measures the phase deviation of the transformer primary versus secondary. As mentioned before, the types of transformer testing we will show in this article a very important test of the transformer testing. Together with extension transformer cvt40, trt4x can output up to 5 kv ac, which is suitable for measuring turns ratio of cvts.
This product is now obsolete and has been replaced by the ttru3. The transformer polarity test determines the vectoral relationships of the various transformer windings. With the cpc 100, the ratio and magnetization current or. However, for some configurations the turn turn ratio is different from the voltage ratio. Shorted turns may result from short circuits or dielectric failures. When testing a transformer for turns ratio, the connections are determined by matching parallel vectors. The iron core inside the transformer is magnetized. This test also includes a passfail limit of individual ratios. The transformer turns ratio tester ttr is device used to measure the turns ratio between the windings example shown below. In the case of an electronic ttr test set, a voltage usually 80 v ac is applied to the tested transformer hv winding.
The megger 550005b singlephase, handcranked ttr transformer turns ratio test set measures the turns ratio and exciting current of windings in power, potential and current transformers. Because a test confirms what you know, if you can apply in real life what you have learned in a classroom, under strict, rigorous and controlled conditions. Testrano 600 energizes all three phases at once allowing simultaneous testing of all three phases, for example, transformer turns ratio with 400 v ll or winding resistance with 33 a. It is a new 250333416450 mva, 23kv delta 240 kv wye generator step up transformer getting ready to energize. M valley forge corporate center 2621 van buren avenue norristown, pa 19403 u.
The table below shows each test with a description, the related specifications and a summary of the benefit provided by that test. The comlink software program serves two main purposes as described above. In case turn turn ratios are requested, values can be. A current transformer will have the line side of its primary marked h1 and the end of its secondary winding with the same polarity marked x1 see figure 2, or it will have h1 and x1 indicated with dots. The primary winding refers to the powered inductor, a circuit element that induces a magnetic. Turns ratio test results should not deviate more than onehalf percent from either the adjacent coils or the calculated ratio. When current flows through the primary winding, the following actions occur. 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. Voltage and turn ratio test of transformer electrical4u. The circuit connection shall be made as shown figure 4. The turns ratio test is capable of detecting shorted turns in the winding, which indicate insulation failure by determining if the correct turns ratio exists.
Measurements are taken by applying a known low voltage across one winding and measuring the inducedvoltage on the corresponding winding. The ttr300 series of threephase transformer turns ratio test sets are designed to measure the turns ratio of power, instrument, and distribution transformers. A rugged and robust design makes these instruments well suited for use in a variety of harsh environments. Transformer bushing cts should be tested using the current ratio test method before the transformer has been completely assembled. The ttr300 series of threephase transformer turns ratio test sets is designed to measure the turns ratio of power, instrument, and distribution transformers in a substation or manufacturing environment.
The transformer turns ratio provides the expected operation of the transformer and the corresponding voltage required on the secondary winding. The results are then presented as a ratio of turns e. Transformer turns ratio test top electrical engineers. Power transformer testing measuring ratio and magnetization current. Performing a transformer turns ratio test with the.
The voltage ratio of a transformer is the ratio of the rms terminal voltage of a higher voltage winding to the rms terminal voltage of a lower voltage winding under specified conditions of load. Strange transformer turns ratio test results electric. Extreme caution must be observed when testenergizing highratio transformers 10 to 1, for example, because high voltages will be present at the transformer. Transformer turns ratio tester electrical power testing. True threephase transformer turns ratio tester trt100. Voltage ratio is proportionally equal to turns ratio.
Transformer testers effectively measure the turns ratio, winding resistance, tap changers, excitation, and polarity of power instrument and distribution transformers. Example of the ttr lcd screen which shows test data. A phase voltage is applied to the one of the windings by means of a bridge circuit and the ratio of induced voltage is measured at the bridge. Ttr300, ttr30047 highvoltage equipment read this entire manual before operating equipment m valley forge corporate center 2621 van buren avenue norristown, pa 194032329 u. Transformer turns ratio test set ttr is available in single and three phase configurations. A transformer turns ratio is the division of the number of turns in the primary winding by the number of turns in the secondary winding by the equation t r n p n s. Turns ratio tests optional test this test is to ensure the turn s ratio of ct at all taps. Megger 550005b singlephase, handcrank transformer turns. Ultimately leading to reduced rewiring effort and shorter testing times.
This test separately energizes two selected windings and measures the inductance value of each winding. Gdbd transformer turns ratio testerturns ratio tester. The transformer turns ratio test is used to determine the number of turns in one winding of a transformer in relation to the number of turns in the other windings of the same phase of the transformer. The primary current of minimum of 25% rated primary current to be injected on primary side of ct with secondaries shorted and the secondary current can be measured and recorded for all cores limits. This test energizes any chosen winding at a specified voltage and measures. This new ttr measures the highest turns ratio range in the.
Testing of power transformers seems like a similar experience. Singlephase, handcranked ttr transformer turns ratio. Ttr20 test set is designed and optimized for the transformer turns ratio testing. True threephase transformer turns ratio tester trt4x. Threephase ttr measuring instruments pdf manual download. The transformer turns ratio test, or ttr test, confirms that the transformer has the correct ratio of primary turns to secondary turns. Working principle of a transformer the basic principle on which the transformer works is faradays law of electromagnetic induction or mutual induction between the two coils. Additionally, the displayed test results were interpreted as a test set calibration check. The megger 550005b handcranked transformer turns ratio test meter measures the turns ratio and excitation current of singlephase power, potential, and current transformers. Deviations in turns ratio readings indicate problems in one or both windings or the. How to perform a power transformer turns ratio test eep. Automatic 3phase transformer turns ratio test set the pattr03a determines the transformer turns ratio using the ieee c57.
The turns ratio test is performed on all taps of every winding. So transformer ration test is an essential type test of transformer. Ttr310e and ttr330a threephase transformer turns ratio test set. True threephase transformer turns ratio tester trt100 singlephase test voltages up to 170 v ac true threephase test voltages up to 3x100v3v ac turns ratio range 0,8 50 000 the best turns ratio accuracy of 0,05% large 7 graphical touch screen display automatic vector group detection.
The tester is powered by a handcranked generator, which eliminates the need for batteries or another external power source. It uses a mixed analogdigital technique to provide the accurate readings of the tested transformer turns ratio. Instruction manual for threephase ttr transformer turn. Testrano 600 threephase power transformer test system. For this reason, voltech at series transformer testers offer five different turns ratio measurement techniques, which can be selected individually to meet specific needs.
Megger ttr20 transformer turns ratio tester manual pdf. Transformer turns ratio tester, turns ratio range 0. Bar and donut type cts do not have a physical primary winding and are considered to have one primary turn. Determine the turn s ratio between the primary and secondary windings. Using this test correctly can help to identify tap changer performance, shorted turns, open windings, incorrect winding connections and other faults inside transformers. We have two cases to do this transformer testing, firstly using measurement device as shown in figure. Biddle ttr transformer turns ratio test sets measure the turns ratio and exciting current of windings in power, potential and current transformers. Transformer turns ratio test sets come in a variety of styles and test connections, however all turns ratio testers have at. Ttr300 series 3phase transformer turns ratio test sets. The typical excitation current test data pattern for a threelegged core transformer is two similar current readings and one lower current reading. View and download megger threephase ttr instruction manual online. The transformer consists of two separate windings placed over the. Ttr300 series 3phase transformer turns ratio test sets finning. Electrical transformer quiz questions electrician exams.
In order to determine which type of turns ratio test is most appropriate for a particular transformer, a number of issues should be considered. Power transformer turns ratio test is an ac low voltage test which determines the ratio of the high voltage winding to all other windings at noload. A voltage transformer has 1500 turns of wire on its primary coil. In this video we walk you through the simple steps for performing a transformer turns ratio test using the vanguard instruments atrt03 s2 threephase turns ratio. If it is required a secondary voltage smaller than the primary voltage stepdown transformer the number of turns on the secondary must be lower than in primary. How to calculate transformer turns ratio sciencing. Tura01 has a fast, easy and accurate ttr measurement features for current, voltage and power trans. This ratio should also equal the voltage of the primary winding divided by the voltage of the secondary winding, as given by v p v s.
The performance of a transformer largely depends upon perfection of specific turns or voltage ratio of transformer. Ct turnsratio modification adding or subtracting secondary turns can also change the ratio of a current transformer. The instruments, when operated as described in the user manual, provide convenient and accurate readings of ratio and phase deviation of power transformers. Transformer testers transformer turns ratio test set. Gdbd transformer turn s ratio tester is specially designed for threephase transformer in power system, especially for transformer of type z winding and other transformers whose zeroload current is relatively high. Basics, maintenance, and diagnostics vii contents continued page 4. The ttr300 series of threephase transformer turns ratio test sets are designed to measure the turns ratio of power, instrument, and distribution transformers in a substation or manufacturing environment. Deviations in turns ratio readings indicate problems in one or both windings or the magnetic core circuit. There are a number of megger turns ratio test sets available.