Nov 17, 2019 a power transformer requires various routine maintenance tasks including measurement and testing of different parameters of the transformer. The accelerating voltage for a television cathode ray tube may be described as extra high voltage or extra high tension eht, compared to other voltage supplies within the equipment. The capacitors are connected between the system voltage and the polarity of a pt. There are two main types of maintenance of transformer. Because replacing a high voltage transformer requires planning for many reasons, including long manufacturing lead times that can exceed a full year, it is widely accepted that asset management, particularly of transformers, is a beneficial contribution to the operation of the grid. For more than a century, power suppliers and industrial companies have relied on siemens for its reliable and efficient power transformers. It must be pointed out that a single measurement on a transformer typically. The accelerating voltage for a television cathode ray tube may be described as extrahigh voltage or extrahigh tension eht, compared to other voltage supplies within the equipment.
Electrical routine testing of high voltage bushings. Use megger mit1020 to measure insulation resistance. By means of cascading, the size of the transformer and the insulation bushing. Greenlee is excited to expand the test and measurement portfolio with the hde high voltage line. High voltage testing 149 the high voltage is applied across the device under test by means of a transformer. Ppt transformer tests powerpoint presentation free to. This test procedure covers the general high voltage tests required for the high voltage, high power alternating current generator described as one of the selected power sources in u. Testing and diagnostic measurements on electric power equipment high voltage engineering, training and seminars. Power transformer oil sampling job safety analysis. High voltage onsite power transformer testing ee publishers. May 10, 20 this test also performed as a routine test of transformer. Standard for acceptance testing specifications for. As the pt secondary is normally grounded through an internal jumper, an external switch is often used to isolate the pt from ground during testing. Testing procedures for hv voltage transformers photo credit.
Some utilities have started doing onsite high voltage testing using mobile test systems, and have reported positive results 1. Power transformer testing procedures and schemes eep. Testing of high voltage cables manual horizon power. Air force technical document afapltr822057, volume 2, high voltage testing. In addition to detecting problems associated with high resistance contacts and connectors, the megger winding tester will also detect open circuits dropout test. Maintenance of transformers a detailed checklist electrical4u. To check the adequacy of main insulation to earth and between winding instruments. Ac dielectric test for acceptance and routine maintenance for liquidfilled power transformers transformer. Before conducting a transformer winding resistance test, it is important to observe all safety warnings and take proper precautions. This type of supply ranges from 5 kv to about 30 kv.
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. When ac hipot tests are used for routine maintenance, the power transformer can be examined at rated voltage for 3 min instead of testing at 65% of factory test voltage. If a very high voltage is required, the transformer is usually build up in stages by cascading. This test also performed as a routine test of transformer. 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. So for ensuring proper performance of electrical power transformer, voltage and turn ratio test of transformer one of the important tests. High power, high voltage, high frequency transformerrectifier for hv industrial applications conference paper pdf available october 2008 with 2,964 reads how we measure reads. Optional perform an applied voltage test on all high and lowvoltage windingstoground. Where high continuous currentcarrying capability is not required and where reclosing or sophisticated relay ing is not justifiedas is the case in the majority of transformer protection applications in mediumvoltage industrial, commercial, and institutional power systemspower fuses offer.
The procedure of the transformer ratio test is simple. Trafositetesting mobile highvoltage test system for onsite testing of power transformers flv english flv movie considerations for the design, manufacture, and retrofilling of power transformers with high fire point, biodegradable ester fluids english pdf technical publication. High voltage insulation testers for the power industry low voltage insulation testers for the electrical contractor insulation resistance testers above 2. William morse a free powerpoint ppt presentation displayed as a flash slide show on id. Ensure that all equipment to be tested is properly grounded and treat all highvoltage power equipment as energized until proven otherwise by using the proper lockouttagout procedures. In automotive engineering, high voltage is defined as voltage in range 30 to vac or 60 to 1500 vdc. When the insulation power factor is measured at a relatively high temperature and the corrected values are unusually high, the transformer should be allowed to cool and the measurements should be repeated at or near 20. Almost all of them, ranging from power ratings from 20 mva to units well above 1,000 mva,and 20 kv to 1,100 kv are tailormade. A power transformer requires various routine maintenance tasks including measurement and testing of different parameters of the transformer. Optional perform an applied voltage test on all high and low voltage windingstoground. Check of phase displacement the polarity of singlephase transformers and connection symbol of threephase transformers shall be checked in each winding. Testing and diagnostic measurements on instrument transformers. Power transformer testing procedures and schemes photo credit.
Pdf high power, high voltage, high frequency transformer. Basics, maintenance, and diagnostics vii contents continued page 4. The purchase, preparation, assembly, operation and maintenance of transformers represent a large expense to. Morgan tm schaffer transformers the inside view transformer tests oil tests and online monitoring can increase transformer life expectancy by. We perform one group on a routine basis known as preventative maintenance, and the second group on an adhoc basis i. Testing power transformers high voltage transformers are some of the most important and expensive pieces of equipment required for operating a power system. The voltage ratio shall be measured on each tapping and verified aginst manufacturer approved power transformer testing procedure. Verify correct secondary voltage phasetophase and phasetoneutral after energization and prior to loading. Highly specialized for design of lvmv switchgears and lv high power busbar trunking power substations. The ac hipot test values for voltages up to 69 kv are presented in table 1. The ac hv test value should not surpass 75% of the factory test value. The purchase, preparation, assembly, operation and maintenance of transformers represent a large expense to the power system.
Power transformer testing swp check this is the latest process zone version before use. Hence, it demands special consideration during routine maintenance. Testing power transformers highvoltage transformers are some of the most important and expensive pieces of equipment required for operating a power system. Castcoil transformer a transformer with highvoltage coils cast in an epoxy resin. C electrical power from one voltage to another voltage keeping the frequency same by electromagnetic induction discover the worlds research 17. Standard for acceptance testing specifications for electrical. A potential transformer is a conventional transformer having primary and secondary windings. Ce mark to indicate thirdparty approved or selfcertification to specific requirements of the european community. High voltage testing requires larger power sources and on site generation and transformer equipment to produce the power and voltages required. Testing procedures for hv voltage transformers include general inspection, insulation resistance, polarity and turns ration tests.
High voltage transformers are some of the most important and expensive pieces of equipment required for operating a power system. Alok pandey assistant professor assistant professor department of electrical department of electrical engineering engineering a seminar on high voltage testing of electrical transformer presented by hari shankar singh. Apr 10, 2015 high vol tage testing of transformer by hari shankar singh 1. It is typical the use of high voltage testing on transformers to confirm performance. Page 2 of 14 standard work practice sp0504 ver 4 ergon energy corporation limited abn 50 087 646 062 ergon energy queensland pty ltd abn 11 121 177 802 sm0701. We just apply three phase 415 v supply to hv winding, with keeping lv winding open. Routine tests and type tests of transformers electrical4u. Testing of hv cables supplementary information page 1 of 24 reference sp0407r02 ver 2 ergon energy corporation limited abn 50 087 646 062 1. Cvts are often used in high voltage 115kv and higher applications and use a series of capacitors as a voltage divider. To ensure sufficient clearance between the windings and between winding and earth. Ensure that all equipment to be tested is properly grounded and treat all high voltage power equipment as energized until proven otherwise by using the proper lockouttagout procedures. Power transformers are subject to several electrical, mechanical, thermal, and environmental stresses during regular operation, with an expected life cycle of more than 30 years.
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