If you are looking for something specific, dont hesitate to contact us. Here it makes sense to intelligently choose, or at a minimum order, the tests to be performed based on symptoms of the transformer, operating and test history, etc. 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. If the resistance of the insulation is high, the pointer of the moving coil deflects towards the infinity, and if it is low, then the pointer indicates zero resistance.
Measuring a transformers dc resistance from one external terminal to another can reveal a great deal of. This generator supplies dc power to the coil that is under the influence of a. Attach the test lead connectors to the megger testing instrument, then to the test item. The generator has centrifugal clutch due to which the generator supplied the constant for the insulation test. Turnsratio test results should not deviate more than onehalf percent from either the adjacent coils or the calculated ratio. Test interphase resistance by disconnecting the leads from each terminal with a flathead screwdriver, then touch any two terminals with the two probes.
At each step, test voltage should be applied for the same length of time, usually 60 seconds. How to do megger testinsulation resistance for transformer. The megger insulation tester is essentially a highrange resistance meter ohmmeter with a builtin directcurrent generator. Ir value of transformers voltage test voltage dc lv side test voltage dc hv side min ir value. Meggers experience in the design and production of oil test sets also reaches back to the early 20th century, when pioneering equipment was produced by foster transformers, a company that became part of megger group in 1968. Weve assembled helpful technical guides on insulation testing from leading manufacturers in the field. Transformer testing commissioning, routine, diagnostic. The easytouse software interface, powerdb, minimizes time required to learn how to use the delta4000 and perform these tests correctly.
What is the megger test procedure for transformers. The complete guide to electrical insulation testing. Megger leads to be connected to lv and hv bushing studs to measure insulation resistance ir value in between the lv and hv windings. Find here insulation testing and continuity, power protection, power transformer testing, power cable infrastructure, cable fault location, general electrical test. The goal is to determine if the insulation of a wire has been compromised. Moulded test vessels give repeatable results with lock in precision electrode gap setting adjustment wheels. The transformer resistance testing will reveal a lot of details about the transformer by measuring the winding resistance of a transformer from one hv transformer bushing to another. The insulation resistance test is of value for future comparison and also for determining if the transformer is to be subjected to the applied voltage test. Meggers delta4000 automatically produces the itc for each transformer and provides confidence that the power factor tan. The megger ttr series of instruments determines the transformer turnsratio using the ieee c57. Insulation resistance test of transformer is essential type test. The instrument aborts the test if interlock circuit opens. Be sure to isolate the transformer before attaching the lead connectors.
A senior tech once told me the megger guard terminal is the same potential as the negative terminal. Basics, maintenance, and diagnostics x contents continued page 9. Meggers automatic laboratory oil test sets perform accurate breakdown voltage tests on mineral, ester and silicon insulating liquids. The megger test or insulation test is carried out to ensure the healthiness of the overall insulation system of an electrical power transformer. Mineral oil is the most common insulating fluid and has been in use since the late 19th century. The test set outputs an excitation test voltage to the transformers primary windings and measures the voltage at the corresponding secondary winding. Hand driven megger test consists of a handle that is used to drive a generator inside the megger. I cover the different test methods, an analogy on how insulation testing works, safety and the use of insulation test equipment. Insulation resistance is the ratio of applied voltage to the resulting current at a specified time after the. The recommended ratio for the test voltage steps is 1 to 5. A guide to transformer winding resistance measurements. Insulation resistance test of transformer is divided into three parts.
View and download megger threephase ttr instruction manual online. M 2621 van buren ave norristown, pa 19403 2329 6106768500. Routine tests and type tests of transformers electrical4u. The dc resistance of a transformer winding can indicate the internal temperature of the winding when the resistance at ambient is compared to the hot resistance.
Megger leads to be connected to hv bushing studs and transformer tank earth point to measure insulation resistance ir value in between the hv windings and earth. The standard megger testing equipment is used, the line. Basics, maintenance, and diagnostics vii contents continued page 4. In this video you will find out how to test 3phase induction motor. Transformer testing with a megger dlro10hd jm test systems. In addition to detecting problems associated with high resistance contacts and connectors, the megger winding tester will also detect open circuits dropout test. May 10, 20 insulation resistance test of transformer is essential type test. Megger threephase ttr instruction manual pdf download. You do this by using a high voltage and looking for voltage leaking through the insulation. Guide to transformer winding resistance measurements measuring a transformers dc resistance from one external terminal to another can reveal a great deal of information about the transformer. The test measures the insulation resistance from individual windings to ground andor between individual windings. Disconnect all the line and neutral terminals of the transformer.
First we will disconnect all the line and neutral terminals of the transformer. We supply a broad range of megger programma instruments. The megger is the instrument uses for measuring the resistance of the insulation. For the detailed technical specification of them please refer to the respective data sheets. As an insulating liquid, oils most important property is a high dielectric strength and as a cooling liquid, a low viscosity is paramount. Instruction manual avtm ttr100 for singlephase handheld ttr. The voltage ratio is displayed and compared with the expected target ratio.
Meggering insulation resistance testing of drytype. Where as in electronic type megger battery are used to produce the testing voltage. A practical guide to earth resistance testing test equipment. Firstly measure insulation resistance between low voltage windings and the main body of the transformer. He showed that, if the electrode depth b is kept small compared to the distance between the electrodes a1, the following formula applies. Mar 28, 2018 in this video you will find out how to test 3phase induction motor. Megger leads to be connected to lv bushing studs and transformer tank earth point to measure insulation resistance ir value in between the lv windings and earth. The typical excitation current test data pattern for a threelegged core transformer is two similar current readings and one lower current reading. Megger transformer test testing testers analyzers testing. Bruce hembroff, cet, manitoba hydro matz ohlen, megger sweden peter werelius, megger sweden. Instruction manual avtm ttr100 for singlephase handheld.
Sverker 900 measuring instruments pdf manual download. A catalogue, for quick reference, of the range of megger test instruments for the maintenance of electrical power systems. Measuring a transformers dc resistance from one external terminal to another can reveal a great deal of information about the transformer. For three phase transformers, we need to test winding l1,l2,l3 with substitute earthing. The list of electrical tests that should be used to diagnose a transformer is all inconclusive. Aug 16, 2014 the procedure of the insulation resistance test are given below first, disconnect all the line and neutral terminals of the transformer. The procedure of the insulation resistance test are given below first, disconnect all the line and neutral terminals of the transformer. For good insulation, the resistance usually reads in the megohm range. Im not sure if this holds true with modern test equipment, but i think this should be taken into consideration when guarding equipment that could be damaged by a high test voltage, such as a low voltage transformer winding. The procedure of insulation resistance test or megger test are given below. This test is often performed by applying an ac voltage but can also be done with a dc voltage.
Transformer testing the proper life management of transformers requires a variety of information about the transformer s condition, which cannot be provided by one test alone. Hence, it demands special consideration during routine maintenance. Step voltage test method in this test, the operator applies two or more test voltages in steps. The easytouse software interface, powerdb, minimizes time required to learn how. Dielectric testing may be destructive in the event of a fault, depending on the test levels and. If you fail to maintain your transformer with regular insulation resistance testing as can be carried out by the megger transformer ohmmeter mto series of. Please find all available data sheets listed below.
How to test a threephase motor with a megger hunker. 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. You can trust an authorised megger distributor to help you choose the right test equipment. Threephase ttr measuring instruments pdf manual download.
This test is carried out to ensure the healthiness of the overall insulation system of an electrical power transformer. Today, all of meggers oil test set design, development and manufacture is carried out at the companys. Insulation resistance testing is a nondestructive test procedure. Megger 550005b singlephase, handcranked ttr transformer. The testing voltage is usually 500, or 2500 v which is generated by the hand driven generator. Program the selector switch to meet the test voltage requirement. The test measures the insulation resistance between the phases andor between phase and ground. Megger guide to electrical insulation testing pdf instrumart. Release the test button after completing the reading. The constant voltage is used for testing the insulation having low resistance. As the voltage increases in external circuit the deflection of pointer increases and deflection. If you cant find your desired data sheet below please contact us were always happy to help out. Figure 2 typical megger test instrument hookup to measure insulation resistance.
The standard megger testing equipment is used, the line terminal of which is connected to the winding or core bolt under test. Procedure of insulation resistance test of transformer. High power test and diagnostics combination for medium voltage cables. Insulation testing technical guides weve assembled helpful technical guides on insulation testing from leading manufacturers in the field. Insulation testing technical guides megger insulation. Powerfactor or dissipationfactor tipup exceeding 1. Megger test equipment help to measure transformer insulation resistance, winding resistance, sweep frequency response analysis, and oltc diagnosis tests enable the assessment and overall health of the transformer to be determined. The wire itself is usually copper or aluminum, which is known to. Megger s comprehensive set of transformer testing tools provides a complete view of your transformer s health. The result obtained is a voltage value usually expressed in kilovolts kv.
Megger working principle types history uses of megger. Test record card pack of 20 6111216 black test lead with large alligator clip 6220295 red test lead with large alligator clip 6220586 green test lead with large alligator clip 6220587 set of test leads with fused prods fpk5 v a. Insulation resistance test and oil test of distribution transformer. This current usually at an applied voltage of 500 volts or more is measured by the ohmmeter, which has an indicating scale. We use megger test at low voltage side as shown in fig. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. The mto210 transformer ohmmeter is a lineoperated, fieldportable instrument designed specifically to measure the dc resistance of all types of magnetic windings safely and accurately.
Megger regularly audits the performance of distribution partners to ensure they meet standards for technical proficiency and customer support. Bureau of standards now nist developed the theory behind this test in 1915 see reference pg. The application of increased voltage creates electrical stresses on internal insulation cracks. Ttr100 highvoltage equipment read the entire manual before operating. Ttr330, ttr33047 highvoltage equipment read this entire manual before operating. Well learn how to identify windings, check windings resistance and insulation resistance. Transformer testing type tests and routine tests of. The megger guide to insulating oil dielectric breakdown. Insulation resistance test or megger test of transformer. Megger and power factor windings, bushing and arrestors. View and download megger sverker 900 application note online. This generator supplies dc power to the coil that is under the influence of a magnet.
A passion for the business of test and measurement over 100 years ago in 1885 to be precise sydney evershed. The generator can be handcranked or lineoperated to develop a high dc voltage which causes a small current through and over surfaces of the insulation being tested fig. Figure 2typical megger test instrument hookup to measure insulation resistance. Meggering insulation resistance testing of drytype power. Press the test button to activate the preset test voltage. The megger guide to insulating oil dielectric breakdown testing. Some unknown facts was presented at the 2020 neta powertest conference in chicago, il. The transparent, shielded lid and large test chamber enable easy access to the test vessel. Transformer testing commissioning, routine, diagnostic megger. Insulation resistance tests megger test are carried out on all windings, core and core clamping bolts. It can test transformers and rotating machine windings and perform lowcurrent resistance measurements on connections, contacts and control circuits.