The basic principle of operation of a transformer is explained in chap. In electrical systems and equipment third edition, 1992. The bushing is designed for the following cantilever load applied to the midpoint of the top end terminal perpendicularly to the bushing axis. Bushings are critical components in all electrical networks, as their chief role is to bring current at high voltage through a grounded barrier. Highvoltage bushing maintenance and testing explained. A good indication of insulation deterioration is a slowly rising power factor. In this video well be looking at how a transformer works covering the basics with transformer working animations. In most cases, the information contained in this catalog should be sufficient for the proper selection of the instrument transformer best suited for your application. If they went unnoticed or unattended will results into a failure. Chinsun 52kv 500kv transformer bushing and wall bushing. A varying current in any one coil of the transformer produces a varying magnetic flux, which, in turn, induces a varying electromotive force across any. The bushing cover gua an 002 is mounted around the top skirt of the transformer and arrester bushings.
The general constructional details, are shown in fig. A bushing can be made of resin, thermoplastic or ceramic. To prevent electrical catastrophes and optimize hv bushing service life, the following preventive maintenance and testing procedures should be performed at. Transformer online electrical engineering learning site. How does a transformer work working principle electrical. Crosslink was recently tasked with reverse engineering a dated porcelain bushing in an aging transformer. These failures most commonly cause transformer fires which may result in huge collateral damages of switchyard. Testing of transformer for its reliability ijert journal. Micafil ris transformer bushings easydry dmboa 24170 kv english pdf brochure 52 kv to 550 kv transformer oil impregnated paper bushing english pdf brochure transformer bushing toe technical guide english, chinese pdf instruction transformer bushing, type toe installation and comissioning guide english pdf instruction. Bushings are usually associated with voltages above 100 volts. The primary function of a bushing is to provide an insulated entrance for an energized conductor into a highvoltage apparatus tank or chamber. The bushings used for reactors, transformers, and switchgears have rated currents of 800, 2500, and 4000 a, respectively. Transformers greenbook edm application of underground distribution transformers 062111 page 6 of 26 rev.
Therefore, the bushings of 52 kv rating are provided for 33 kv tertiary winding. Reference 3 indicates that 30 % of generator stepup transformer failures are caused by a bushing malfunction, and that they also cause 56 % of failures accompanied by fire. Bushing testing solutions doble engineering company. Our customer based in texas required the engineering design and manufacturing of a number of large epoxy transformer bushings and insulators some weighing up to 150lbs per piece and ranging from 600 amps to 4500amps. Basics, maintenance, and diagnostics vii contents continued page 4. Ratio test for transformer bushing ct electric power. Transformer bushing operating principle in electric power, a bushing is an insulated device that allows an electrical conductor to pass safely through a grounded conducting barrier such as the case of a transformer or circuit breaker. Pdf different defects diagnosis of an elecrical power. Square d 600 volt rated current and voltage transformer s are fieldproven in well over a million installations where accuracy and longer, more dependable operation are essential. Bushings for ac transformers and reactors bushings. Based on iec 607, for 500 kv transformer, following data are specified. The type of design and the materials within a condenser core may differ between manufacturers, but the design intention is the same. Bushing current transformersbushing current transformers. Removable stud bushing well provisions for easy removal of broken parts from both the bushing well and insert.
Figure 11 bushing mounted on an oilfilled transformer 4 figure 12 550 kv bushing installed in mounting frame atop the berkeley simulator 4 figure longitudinal section through a modified 550 kv porcelain bushing 5. The active part of the bushing consists of an oil impregnated paper oip core manufactured from superior grade kraft insulating paper with condenser graded layers for field control wound under tension on central tube conductor. In majority of the transformers, hv and lv line terminals are taken out from tank through bushings. The power factor of a bushing in good condition will remain relatively stable throughout the service life.
A primary part of commissioning a transformer involves testing it after its installation in the field. It provides the basic information on bushing tests and how they relate to the power transformers. Pdf on oct 1, 2016, abdelkader elagoun and others published different defects diagnosis of an elecrical power transformer bushings find, read and cite all the research you need on researchgate. Pdf guide for transformer maintenance guide for transformer. The test engineer may not directly perform all of the following tests and. The bushing mounting angle can be from 0 to 75 from vertical. The ground shields are fabricated of aluminum and fit closely over the top of the current transformer. You need condition monitoring tools that provide accurate data, robust analysis and reliable alerts. Hv bushing porcelain insulator petticoat broken cracked. What is the purpose of using bushings for a transformer.
In axial direction, the ggf bushings can be loaded with 3. All the transformers windings are connected with the high voltage lines, therefore the end connection of the transformer should. Capacitance of c 1 in bushing of power transformer rated 500 pf, 30. International conference on electrical engineering and.
Transformer components type a bushings instructions for. The porcelain bushings used in the uhv ac pilot and demonstration project can withstand class d pollution conditions, can have a specific creepage distance of no less than 25 mmkv, and can have minimum spacing between sheds of 80 mm. The main insulation of hv transformer bushings constructed using. This allows you to effectively identify developing problems, prevent transformer and bushing failures, and manage risk. High voltage bushing wells pdf 600a epoxy bushings pdf distribution transformer lv bushings. Follow instructions in the transformer manual carefully. Pdf download the technical brochure for the iec bushings. Series multiple switches offer easy reconnect of transformer windings from series to parallel with a simple turn of the switch on a deenergized. Tap changing arrangement off circuit tap changing switch off circuit tap changing link on load tap changer two earthing terminals lifting lugs drain cum filter valve pressure relief device silica gel dehydrating breather.
New techniques for the monitoring of transformer condition. Generator stepup autotransformer stepdown pads transformer transformer 11510 or. The shield purpose is to prevent a bushing flashover from penetrating the. The book covers the different technologies used in bushing construction and will examine the techniques used in the selection of bushings for power transformers. In electric power, a bushing is an insulated device that allows an electrical conductor to pass safely through a grounded conducting barrier such as the case of a transformer or circuit breaker. High voltage transformer bushings rhm international. Troubleshooting transformer in power substation and detailed. This amounts to a rigorous examination of the transformer intended to. Several investigations of transformer failures have been done in the past, e. The most common cause of failure is moisture entrance through the top bushing seal. Available online at 9th ecoenergy and materials science and engineering symposium. All the transformer main components are discussed core.
Replacing a high voltage bushing is a critical procedure that should. A potential transformer is a conventional transformer having primary and secondary windings. Hvdc transformer bushing, type ggf installation and. Transformer testing commissioning, routine, diagnostic.
Transformer bushing provides a very effective insulation be. Ensure cleaning of porcelain bushing during each inspection. Condenser bushing construction generally, the bushing of power transformer is made as condenser type, consisting of several paper insulation layers separated with conductive foils for each layers as shown in fig. Bushings transformer insulation and components abb. With the benefit of decades of bushing testing and analysis, doble provides tools, techniques, and services to identify signs of incipient bushing failure. A transformer operates on the principals of electromagnetic induction, in the form of mutual induction. Acceptance and routine maintenance tests most often used for checking the condition of bushings are doble power factor tests. The external insulation types of the bushing are brown porcelain housing insulators and grey uv protective silicone rubber sheds. Table 1 shows the capacitance of c 1 in bushing of power transformer oilimpregnate, paperinsulated type rated 500 pf, 30. Ratio test for transformer bushing ct engtips engineering. That what i dont understand there is a sizing of the transformer neutral bushing.
Moisture causes deterioration of the bushing insulation and can result in explosive failure, causing extensive transformer and other equipment damage, as well as hazards to personnel. High voltage transformer bushing problems request pdf. The bushing can withstand 250 nm torque on the outer terminal. Choose doble doble brings clarity to the complexity of condition monitoring. It may be a break in the turns or end lead, flash marks on the end coil and earthed parts close to it. One reason may be because bushings are often tested offline to measure capacitance, dissipation factor and power factor. There is a chapter on maintenance and a guide for replacing bushings. Transformer components and insulation english pdf brochure micafil ris transformer bushings easydry dmboa 24170 kv english pdf brochure 52 kv to 550 kv transformer oil impregnated paper bushing english pdf brochure transformer bushing toe technical guide english, chinese pdf instruction. Reverse engineering a transformer bushing replacement. Abb kuhlman engineered designs instrument transformers.
Request pdf high voltage transformer bushing problems bushing is an important part. Back to the basics current testing valence electrical. The transformer does this by linking together two or more electrical circuits using a common oscillating magnetic circuit which is produced by the transformer itself. Pacific earthquake engineering research center peer 199802 may 1998. About 90% of all preventable bushing failures are caused by moisture entering through leaky gaskets, cracks, or seals. Failure of transformer in power substation is not a sudden phenomenon, for that matter each and every failure will take place only after alerting through some presigns. A bushing failure may be catastrophic, which is why doble offers a complete portfolio of products and services to help you track bushing health, from insulation analysis through teardowns.
This 3d animated video discusses the three main types of transformers used in the power engineering industry, their parts and functions. Pacific earthquake engineering research center and the national science foundation. Among the reasons for transformer outages, bushing failures are often the cause. Transformer components and insulation english pdf brochure micafil ris transformer bushings easydry dmboa 24170 kv english pdf brochure 52 kv to 550 kv transformer oil impregnated paper bushing english pdf brochure transformer bushing toe technical guide english, chinese pdf. Failure to relieve this stress at the bushing connection may result in damage to the bushing seals and loss of oil.
Faculty of electrical engineering, department of electrotechnology and. Design of 33kv transformer bushing insulator from nr and hdpe. Nov 04, 2018 this 3d animated video discusses the three main types of transformers used in the power engineering industry, their parts and functions. Figure 11 bushing mounted on an oilfilled transformer 4 figure 12 550 kv bushing installed in mounting frame atop the berkeley simulator 4. Bushing current transformersbushing current transformers 600v. Pacific earthquake engineering research center seismic. A schematic drawing of a singlephase distribution transformer appears in fig. This volume provides timely, practical advice to those seeking to.
Troubleshooting transformer in power substation and. There is a 47005a bushing ct installed at low voltage b phase. A bushing may also serve as a support for other energized parts of the apparatus. Blume states the following on wye wye connection 2. Rif provides state of the art technology for bushings. Abb offers a broad range of bushings for transformers, reactors, switchgear, and traction and wall applications in both oil impregnated paper oip and resin impregnated paper rip technologies. According to these investigations bushing failures caused 17% of transformer failures. Doble online monitoring solutions know the condition of your. The cutout guard gua an 006 is installed on the top of each cutout. The isolated phaserun is then fed with conditioned air, as. Transformer bushing operating principle electrical4u. Transformer bushing cts should be tested using the current ratio test method.
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