POWER TRANSFORMERS: 16MVA and 72,5kV and above, oil-immersed transformers are described as Power Transformers. Power transformers require distinct expertise and experience in particularly insulation and cooling issues. BEST is capable of designing, manufacturing and testing power transformers up to 1250MVA, 765kV with its modern plants thanks to 56 years domestic and international experience. Although they essentially have similar structure, particularly the differences in customer requirements and specifications call for new design for each transformer. Therefore, BEST Electrical and Mechanical design groups handle each transformer separately. BEST manufactures power transformers that meet every requirement in every power and voltage range above 16MVA. There are 4 types of power transformers.
Auto Transformers:These high-voltage transformers are particularly used for connecting grids at different voltages.If voltage levels are close, autotransformers provide economical advantage. In autotransformers, measures should be taken particularly against short circuits. Three-phase and single phase autotransformers up to 550kV, 500MVA, manufactured in the BEST plants have also successfully completed short circuit tests and they have been in operation since their first introduction in the grids.Production capacity up to 1250MVA, 765kV.Constant Flux Voltage Variation or Variable Flux Voltage Variation designs.
Step Up/Down Transformers: Generator transformers amplify generator output voltage to transmission line voltage. They should be designed in consideration of generator characteristics.They can have Neutral and Load step switches. Generator transformers have vital importance in meeting continuous and quality energy need of grids.Production capacity up to 1250MVA, 765kV.Designs made in consideration of overexcitation and loading curves of generators.
Railway Transformers:These transformers reduce line voltage to the supply voltage of railway line.Issues specific to railway systems, notably high overcurrents, should be taken into consideration. BEST also contributes to this field with transformers that it provided to many railway transportation systems including Marmaray.Production capacity up to 100MVA, 420kV.Special Care made to frequently repeated overcurrents.
Mobile Transformers:These transformers are used at mobile switchyards and loaded on transportation vehicles such as truck or railroad carriage.As they can be used at multiple points of the grid, compliance with multiple voltage levels required. BEST manufactures transformers for mobile switchyards in many countries in cooperation with its experienced solution partners.Production capacity up to 100MVA 245kV.Land and railroad transportation limitations are complied.
SPECIAL TRANSFORMERS:Special transformers are used in special applications in the industry and in the grid. They are produced in small numbers and they generally have to deal with overcurrents, overvoltages and reactive loads under severe conditions. This requires each of the following transformers to be particularly addressed. A longer design and production process is required for special transformers than standard type power transformers. Special transformers are regarded as the peak of transformer industry due to know-how, diligence and accuracy required by both design and production technology.There are 5 categories under special transformers.
Furnace Transformers:Furnace transformers are used in iron and steel plants for melting metal. The metal in melting pots are melted with very high currents.Additional measures should be taken in furnace transformers against these high currents, possible short circuits and overcurrents.Production capacity is up to 360MVA,36kV.Must endure against short circuits and overcurrents.
Furnace Reactors:They are used to improve operating regime of furnace transformers in iron and steel plants.Measures should also be taken on furnace reactors against all kinds of overcurrent and voltage caused by furnace operation.Production capacity is up to 250 MVAr,36kV.Increases reactance of the system and also enables reactance regulation.Must endure against short circuits and overcurrents.Can be in the same tank if required.
Shunt Reactors:These special transformers are used for compensating capacitive load formed in power transmission lines at times of low load.Therefore, they are rated according to their reactive powers. They increase energy quality and efficiency of the grid by preventing over voltages besides their duty of compensation.Production capacity is up to 350MVAr,550kV.Acts as inductive load on high voltage transmission lines.
Current Rectifier Transformers:These transformers are used for feeding systems with direct current requirements. Their main areas of use are purposes of electrolysis in metallurgy plants and railway lines.There are different approaches in the design of current rectifier transformers according to high output voltage or high output current requirements. They are produced with different structures according to number of pulses.Production capacity is up to 60MVA, 36kV.Can be with Bridge Assembly or Star Point Reactor.It is produced in 6, 12 and 24 pulses.
Phase Shifter Transformers:They are used to determine energy flow direction at connection points of high voltage grids. They are used to obtain different phase angles than inputs by using special coil structures at outputs.Power and voltage of these transformers are limited to the capacity of the initial switch. Furthermore, customer and grid requirements should be understood well due to their role in the grid.Production capacity is up to 600MVA 550kV.Available application types; Single Active, Multiple Active, Booster, Autotransformer.