Electric Co. Ltd. TRANSFORMERS UP TO 750 kv
CONTENTS General... 2 Products... 3 Construction...4 Magnetic core... 4 Windings...5 Frame structure... 6 Connections...6 Tap changer and motor drive...7 Tank... 7 Oil conservator, protection relays... 8 Cooling system... 9 Bushings and cable boxes... 9 Control box... 9 Tests...10 Transportation...... 11 Production and Quality Assurance...12 On the cover: 400 kv, 250 MVA Autotransformer for Hévíz S/S, Hungary. Low noise design, sound pressure level 61 db(a). Ganz Transelektro Electric Co. Ltd. 1
GENERAL Ganz Transelektro designs and manufactures single and three phase, mineral oil immersed transformers for outdoor or indoor operation, in the power range up to 600 MVA and the voltage range up to 750 kv. The transformers are provided with oil-air or oil-water cooling (ONAN, ONAF, OFAN, OFAF, ODAF, OFWF, ODWF coolings are available). The transformers are completed with the necessary fittings for transportation, operation and protection during service, and with monitoring units according to the special requirements. The design principles of the transformers at Ganz Transelektro are: to satisfy the customer requirements; acc. to the request: - to optimize the sum of the investment and operation costs, or - to provide the needed no-load and load losses with the most economic use of materials and the lowest manufacturing costs The transformers are subjected to routine and type tests as required by IEC, VDE or ANSI (or other specified) standards depending on the customer's requirements. 3D drawing of a 123 kv, 63 MVA Substation Transformer. Design of the power transformers is going on with the latest CAD softwares. 2 Ganz Transelektro Electric Co. Ltd.
PRODUCTS High voltage power transformers (with or without voltage regulation) 750 kv, 420 kv or 245 kv autotransformers 420 kv, 245 kv or 123 kv generator transformers 420 kv, 245 kv or 123 kv substation transformers Medium voltage power transformers (with on-load tap changer, off circuit tap changer or constant ratio) substation transformers generator transformers transformers for railway substations start up and auxiliary transformers of power plants Special transformers and reactors rectifier transformers voice-frequency-coupling transformers phase-shifting transformers furnace transformers built in reactors for transformers short-circuit limiting reactors shunt reactors Vehicle transformers, smoothing reactors transformers for electric multiple-unit trains transformers for main line locomotives smoothing reactors Transformers with special active part rectifier transformers with cross yoke core transformers with auxiliary yoke, three phase core multi-winding transformers transformers with split winding transformers with indirect voltage regulation (built-in or separate regulation transfer) GanzTranselektro Electric Co.Ltd. 3
CONSTRUCTION Magnetic Core Core limbs fixed to the base, compressed by glass-epoxi bandages. The magnetic cores are manufactured of cold rolled grain oriented steel sheets. The steel sheets in the core limbs and in the yokes are clamped together by glass-epoxi bands. Through going bolts are not used. The standard design is the core type transformer. The suitable construction of the frame structure, the preset surface pressure of the lamination, the proper flux density and the glueing of lamination edges after clamping ensure a moderate level magnetic noise and prevent the increase of no-load losses after impulse voltage test. Cooling of the core is assured by suitably arranged oil ducts. The step lapped joints of the core laminations reduce the additional losses arising in the corner portions. 4 Ganz Transelektro Electric Co. Ltd.
Windings Two layer helical LV winding made of continuously transposed conductor without paper on a horizontal winding machine for a step up transformer. Material of the windings is electrolytic copper. Single conductors, twinned conductors or continuously transposed conductors are used. Generally, the conductors are insulated with natron-cellulose kraft paper, but in the lower voltage range helical windings are also manufactured of conductors without paper insulation. In the standard design the voltage level of the windings increases from the innermost winding toward the outermost one. In case of special requirements, the sequence of the windings can be different. By arranging the regulating turns in separate coil stacks, the short circuit withstand ability of the transformer is ensured in all of the tap positions. The main insulation and the end insulation consist of oil ducts, transformerboard cylinders and rings, coverages and end supports. The workshop has ten horizontal and two vertical winding machines. GanzTranselektro Electric Co.Ltd. 5
Frame Structure The frame structure is suitable for clamping the core and the windings, holding the cleat bars and withstanding the forces arising in operation, fault conditions or transportation. The lower and the upper frame beams are held together vertically by steel flitchplates. For clamping the beams to the core horizontally, the opposite side beams are fixed to cross-bridges by insulated tie bolts at the ends of the core and glass-epoxi bandages are used in the window. The iron core rests on antivibration pads with steel-supports on the bottom girders. These supports are constructed to prevent the possibility of core displacement during the active part is lifted. Connections The ends of the windings are connected to the terminals of the tap changer, and to the bushings of the transformer by insulated, well fixed, round wires or rectangular bars made of copper. The connections to the terminals and to the bushings are made of flexible connecting elements. Active Part of a 145 kv, 110 MVA generator transformer with off-circuit tap changers for alternative rated HV voltages and on-load tap changer for voltage regulation, manufactured for Maghera Azotati P/P, Italy. 8 6 Ganz Transelektro Electric Co. Ltd.
Tap Changer and Motor Drive Ganz Transelektro transformers are equipped with tap changers produced by the best European manufacturers. The tap changers are in accordance with the relevant IEC standards. The on-load voltage regulation is performed by Dr. Jansen system tap changer. This tap changer functionally consists of two parts: the tap selector and the diverter switch. The diverter switch is always placed in a hermetically sealed oil filled chamber in order to avoid any contamination of the oil in the main tank of the transformer. The motor drive is mounted onto the wall of the transformer tank. The position of the tap changer is indicated optically in the box of the motor drive and different types of electrical remote indication can be available. On request, the tap changers can be remote controlled. Transformers can be manufactured also with off-circuit tap changers or constant ratio. Tank and Cover The standard construction consists of a deep tank and a cover, but for larger transformers or on special request we also manufacture bell type tanks. The transformer tank is a welded construction of high strength boiler steel plates. The suitable mechanical strength is ensured by stiffeners. The tank of the transformer lies on a rigid steel base frame, which is built into the tank and forms one unit with it. Earthing terminals are placed on both sides of the tank. The cover of the transformer is made of ribbed, high strength boiler steel plate. The cover is provided with man-holes and lifting lugs. The lifting lugs are suitable for untanking the inner parts. Detectors of the oil and winding temperature indicators are placed into thermometer pockets. The fixing flanges of the tap changer, the pressure relief device, the bushings and the C.T. terminals are generally located also on the cover. The tank and the cover is fixed together by bolts or welding. GanzTranselektro Electric Co.Ltd. 7
Oil Conservator, Protection Relays The oil conservator is mounted above the transformer tank and rests on a suitable rigid holding frame (or on a separate frame, in case of special request). Generally, the conservator has several separated sections. The largest section is for the thermal expansion of the transformer oil. In case of on load tap changers there is an other section for the thermal expansion of the oil in the hermetically sealed tap changer compartment. Third section or a separate small conservator is necessary if oil filled cable boxes are used. Each conservator section has adequate volume considering the connected total oil volume and the temperature variation in service. The oil of the different conservator sections cannot come into contact. The air space above the oil of each conservator section is connected through a pipeline to an air dryer which is mounted at a comfortable height for handling. The air dryer ensures the breathing of the air space above the oil level and controls the humidity. Syntetic or rubber bag conservators for airtight sealing of the oil are also available. The end-covers of the conservator are fixed by bolts. After removing them the inner part of the conservator can be cleaned. Each separated section of the conservator is provided with o magnetic type oil level indicator. The oil level related to 20 C is marked. An oil filling pipe with a valve is connected to the conservator, a draining valve is located at the lowest point. Buchholz relays are placed in the connecting pipe between the conservator and the tank and between the conservator and the oil filled cable box, if it is used. Between the tap changer and the conservator an oil flow detecting protection relay is placed. 145 kv, 180 MVA Generator Transformer with 24 kv, 6.3 MVA Auxiliary Transformer for Kelenföld P/P, Hungary. Very low noise design, sound pressure level 60 db(a), SF terminal device, facilititating the earthing of 120 kv cable when needed. 6 8 Ganz Transelektro Electric Co. Ltd.
Cooling System The heat generated in the active parts of the transformer is transferred by the oil circulation in the cooling ducts. The greatest part of the heat is dissipated from the heated oil into the ambient air though the surface of radiators or compact heat exchangers. Oil-water cooling is also possible with special heat exchangers. The radiator groups are fitted to the transformer tank through butterfly valves or placed in separated cooling banks. Each radiator group is equipped with oil draining and deareating plugs. The suitable mechanical strength of the radiator groups is ensured by reinforcing ribs. Bushings and Cable Boxes Transformers can be manufactured with bushings, cable boxes or plug-in cable terminals. Generally, the condenser bushings are of small oil volume type. The low voltage bushings are of the solid porcelain type or resin paper type - when required -, and will be placed on a non magnetic steel flange depending on the design requirements. Oil filled or air filled cable connection boxes are available according to the specific requirements. Control Box The control box of the transformer is mounted on the tank wall. This provides accomodation of the control and protection equipment, terminal blocks and glands for incoming and outgoing cables. A thermostat controlled metal-clad heater is provided for eliminating condensation. The box has an adequately sealed hinged door. Single phase and three phase watertight interlocked switch sockets can be fitted on the control box. 72.5 kv, 43 MVA Generator Transformer for Syria. GanzTranselektro Electric Co.Ltd. 9
TESTS In the testroom all the facilities are available for routine and type tests. Our experts perform - meeting the purchaser's requirements - all tests in accordance with any of the standards: IEC, ANSI, BS, VDE, etc. The tests are carried out by means of computer aided data acquisition and evaluation system. Uppon special request Ganz Transelectro perform: short circuit withstand test frequency response analysis radio-interference voltage test etc. High Voltage Testing Equipment detail in Testroom. 10 Ganz Transelektro Electric Co. Ltd.
TRANSPORTATION Transformers can be transported completely filled with or without oil in the main tank, depending on the size. Delivery both on road and rail is possible. In case of transportation without oil, in order to avoid the moisture absorption by the active part, the tank is filled with nitrogen at a positive pressure maintained by a proper equipment. For lifting of the transformers completely assembled they are provided with four lifting hooks welded onto the lifting ribs on the tank wall. For lower lifting there are four jacking pads at the sides of the transformer tank. In order to control the transport stresses of the transformers, depending on their size and way of transportation, transformers are equipped with three-dimension impact recorder. 5.5 MVA, 17.5 kv Auxiliary Transformers for Electrabel Fina CHP, Belgium. The Completly Assembled Transformers were Transported by Trailer. GanzTranselektro Electric Co.Ltd. 11
PRODUCTION AND QUALITY ASSURANCE Ganz Transelektro production units have obtained an ISO 9001 World Standard Certificate for their products, engineering, manufacturing procedures and services in 1994. 16 MVA, 16 2/3 Hz track side transformer delivered for the Swedish Railways was tested by the independent Dutch KEMA Institute. The transformer has withstood 50 short circuit shocks with 40 ka. (The relevant IEC standard prescribes only 3 short circuit shocks.) 12 Ganz Transelektro Electric Co. Ltd.