Megger leads to be connected to lv and hv bushing studs to measure insulation resistance ir value in between the lv and hv windings. Scribd is the worlds largest social reading and publishing site. Power transformer testing and commissioning guidelines r. If i repeat the procedure of measuring the voltage across diode i was able to activate the circuit 7 out of 10 times. The equivalent circuit parameters areavailabletothedesigner ofthetransformers.
What is the basic component in dc or ac power supplies. The second method uses a transformer equivalent circuit and its parameters. A ttr is an extremely useful instrument for testing transformer windings, because it can locate several types of problems within a transformer. Testing procedures for hv voltage transformers include general inspection, insulation resistance, polarity and turns ration tests.
The tags should be highly visible, and as many people as possible should be made aware of their presence before the work begins. The purchase, preparation, assembly, operation and maintenance of transformers represent a large expense to the power system. High voltage transformers are some of the most important and expensive pieces of equipment required for operating a power system. General inspection mechanical checks general visual inspection and compliance with the drawings and manuals. The objective of this experiment is to determine the voltage regulation and efficiency of a transformer by two methods. The paper presents the method of selection, calculation and measurements of generator that is built into the new transformer test station. When making the test on the windings, so long as the phases are connected, together, either by the neutral lead in the case of the star connection or the interphase connections in the case of the delta, it is only necessary to make one connection between the megger and the windings. Use small jumper to short the ct secondary from ct.
But before i start, let me give a brief about transformers and different types. It evolved from the simple gonogo verdict into a sophisticated segment within transformer manufacturing. If this question comes to your mind often, you are definitely at the right place. After, installation of power transformer, several precommissioning tests to be done before putting the transformer in service. When switched off and later switched on, i couldnt get any reading on the op side. First, disconnect all the line and neutral terminals of the transformer. A voltage transformer theory or potential transformer theory is just like a theory of general purpose step down transformer. Transformer installation method statement electrical. Power transformer maintenance and acceptance testing cmafte n 1. Testing power transformers highvoltage transformers are some of the most important and expensive pieces of equipment required for operating a power system. Transformer, operation, testing and maintenance 33kv and below 9. Voltage transformer or potential transformer theory. These can be of electromagnetic of capacitive voltage transformer type cvt.
Testing will commence only after the equipment is completely installed as per approved method statement for the installation of the transformer and released for testing commissioning. Transformer testing has developed considerably over the past years. Dc dielectric withstand test voltage shall not exceed 100 percent of the ac rms test voltage specified in ansi c57. Zeras testing systems can be designed for testing instrument transformer manuell or automatic. A transformer is a device used to change the voltage levels of electricity to facilitate the. This method statement will give a brief steps to be carried out for testing and pre commissioning of transformers. In this article, performance test of faulty distribution transformersalong the streets or roads of. In addition some other tests are also carried out by the consumer at site before commissioning and also periodically. The transformer has been built to standard damage has not been sustained during transit or installation. This is a simplest form of potential transformer definition. Connection on cpc100 will be same as the shown figure. Transformer is the most important equipment in the electrical power transmission and distribution system. Hence, it is essential to inspect and calibrate those instrument transformers at regular intervals.
The results show that onsite tests, including high voltage tests, on high voltage power transformers is fully possible and reliable. All materials and relevant documentation to this testing works shall be checked by the responsible personnel prior to the commencement of testing activities. Along with different precommissioning tests, different instruments associated to the transformer also to be checked. In this test we confirm the ct secondary connection. November 17, 2019 february 24, 2012 by electrical4u.
What is the megger test procedure for transformers. Information about fist transformers,general transformer design drytype and cast resin, protection methods are being referred and more also included in the specific research document. Instrument transformer theory and testing steve hudson, pe engineering manager 10737 lexington drive knoxville, tn 37932 phone. Testing and commissioning instrumenttransformers free download as powerpoint presentation. Dust, grime, humidity, oil, corrosion, vibration, electrical surges, mechanical pulls and lugging and other stressors contribute to the insulations life expectancy, usually a slow and steady decline over time. Repeat the test for the other phases and the other secondary cores. The purchase, preparation, assembly, operation and maintenance of transformers represent a large expense to. Voltage transformer testing swp page 1 of 19 standard work practice sp0508 ver 7 ergon energy corporation limited abn 50 087 646 062 1. Uettdrts24a design testing and commissioning procedures. Our distribution transformer test system dtts has been designed with these requirements in mind, as a multifunctional tool for testing distribution transformers. Contract specific procedure for testing of electrical equipment and 2kv ohl. Purpose and scope the purpose of this standard work practice swp is to provide guidelines for testing methods for capacitive and inductive voltage transformers.
If no evidence of distress or insulation failure is observed by the. Stationary and mobile transformer transformer testing. The performance parameters of interest can be obtained by solving that circuit for any load conditions. Current transformer testing swp check this is the latest process zone version before use. Potential transformer testing ptvt valence electrical. Transformer pd and induced voltage withstand test system. The complete guide to electrical insulation testing.
Current transformers which are in saturation can be subjected to following demagnetization procedure. Page 1 of 9 standard work practice sp0507 ver 5 ergon energy corporation limited abn 50 087 646 062. The standard megger testing equipment is used, the line terminal of which is connected to the winding or core bolt under test. Voltage transformers testing and commissioning guidelines.
Mainly two types of transformer are done by manufacturer before dispatching the transformer mainly 1 type test of transformer and 2 routine test. Use the following test procedure for pt insulation tests. To test the insulation integrity you will need a megohmmeter or hipot rated to produce the specified maximum test voltage. The three phase cylindrical synchronous generator 800 kva, 200 hz with special damper bars is most suitable to be used as a power supply for testing of singlephase and threephase power transformers. Testing power transformers high voltage transformers are some of the most important and expensive pieces of equipment required for operating a power system. Primary of this transformer is connected across the phase and ground. Power transformer testing and commissioning guidelinesr sahoo procedure of power transformer testing and commissioning in transformer testing and commissioning, it can be classified into power and distribution transformers.
A fault leading to an open secondary could cause the primary current to overwhelm the insulation, causing the winding to short circuit. Performance test of faulty distribution transformers along. Ac dielectric withstand test voltage shall not exceed 65 percent of factory test voltage for oneminute duration. Synchronous generator for induced ac voltage test of. The working procedure on how transformers work types. Current transformers testing and commissioning guidelines. Power transformer testing procedures and schemes photo credit. Tm 5686 power transformer maintenance and acceptance. The results and experience accumulated over more than 12 years have shown that, in completion to gis equipment and hvcable systems. Check that all parts of the transformer are properly assembled and tight. The ac hv test value should not surpass 75% of the factory test value. Figure 1 and 2 shows connections diagrams for testing threephase transformer using alternate singlephase source. The need for a comprehensive current transformer testing regime is evident when the alternative is considered.
Testing of power transformers seems like a similar experience. The first method uses measurement of input and output power and voltages. Power transformer testing procedures and schemes eep. With a variac increase current in the ct secondary affected core with other cores open until 1a is reached and then again reduce the current. Pdf transformer is a static device which transforms a. There are various test required on transformer to conform performance of transformer. In order to ensure availability of uninterrupted power supply, it is essential that the condition of transformer is continuously monitored during service as failure of transformer would result in interruption of power supply resulting loss of industrial production and inconvenience to. C electrical power from one voltage to another voltage keeping the frequency same by. Back to the basics potential transformer testing ptvt 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. Testing smps transformer without load electronics repair.
Site testing will be carried out to the mv transformer by the authority approved testing contractor and to be witness by authorities, consultant and contractor. Power transformer testing and commissioning guidelines r 1. Potential voltage transformers testing and precommissioning check potential voltage transformers can be broadly divided in to two type. Insulation tests rest primarily on the overall condition of the electrical equipment used to conduct the test.
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