19/4/13 - Expansion of the product portfolio
Let us introduce you the expansion of the product portfolio of our company about transformers of brand ABB.
» SHPS Lenešice, Czech Republic
» Precheza, Přerov, Czech Republic
» AGC, Czech Republic
» SHPS Bělov, Czech Republic
» Duslo Šala, Slovakia
» Continental, Jičín, Czech Republic
» AB Libeňské doky, Czech Republic
» Dalkia Ostrava - Šverma, Czech Republic
Oil-immersed hermetically sealed distribution transformers
Transformátory SEA patří mezi stěžejní produkty našeho sortimentu. Základy společnosti SEA byly položeny v roce 1959 v Tezze di Arzignano v Itálii. Olejové distribuční transformátory SEA splňují nejnáročnější požadavky na provoz stanované normou IEC 60076-11, jelikož jsou vyráběny pro použití v třídě prostředí E2 (častá kondenzace nebo silné znečištění nebo kombinace obou těchto vlivů) a v třídě klimatu C2 (odolné proti tepelnému šoku a jsou schopny okamžitého najetí v -25°C). Rozsah výroby společnosti SEA je velmi široký, zahrnuje olejové distribuční transformátory, olejové výkonové transformátory, usměrňovačové a pecové transformátory, suché transformátory, reaktory a tlumivky.
Tapping on primary:
Winding conductor material:
Protection degree transformer:
Max. average temperature rise:
|50 ÷ 20 000 kVA
up to 35 kV
±2x2,5 % (or other)
400 V (or other)
Cu or Al
Parameters and drawings
TTO transformers are distribution transformers, filled with insulating fluid. They may be used in both internal and external environments under heavy industrial conditions and they are priced affordably. They are generally provided in a separately sealed design that significantly reduces demands on maintenance or they are alternatively designed with a conservator. Transformers are filled with mineral oil or silicon-based oil at request, which provides increased fire prevention, or with biologically degradable synthetic MIDEL oil.
The core is formed by grain-oriented magnetic sheets, with high permeability and reduced specific losses, separated by inorganic insulation (carlite). The special cutting and assembly of the core allow the “STEPLAP” joints which reduce noise as well as losses and the no load current. The magnetic sheets are pressed by core clamps, realized by bent sheet shapes.
Low voltage windings
The LV winding consists of an electrolytic aluminum or copper sheet conductor. The winding may be round or oval. The special paper used as an interlayer adheres to the surface of the conductor during the drying phase, making the winding more compact and sturdy, able to withstand heavy electrodynamic stresses. The outlet terminals are realized by aluminum or copper plates welded in an inert atmosphere.
Medium voltage windings
The MV winding is made from an enameled copper wire or strip insulated with pure cellulose paper, using automatic or semi-automatic computerized machines. It is generally wound directly above the LV winding. The result is a complete MV+LV coil, very compact and sturdy, able to withstand possible electrodynamic stresses caused by a short circuit. The commutation leads are obtained directly from the outside part of the winding.
Off load tap-changer
Every transformer is equipped with a 5 position tap changer (±2x2,5%) which enables the nominal voltage of the MV winding to be aligned to the available voltage. The tap changer should be adjusted when the transformer is disconnected from the network by using the knob on the lid; the knob can be locked.
Assembly of the active part
The final assembly is carried out with care and accuracy. The three complete LV+MV coils are assembled on the corresponding core legs, followed by the yoke assembly, the locking of the lid, the electric connections and the thermal treatments. Before inserting them in the tank, all transformers are checked to verify the correctness of the connections - the turn ratio and the vectorial group.
|After a careful drying cycle and a final check of the vectorial group , the complete active part is assembled inside the undulated body and finally filled with oil. During this stage, the transformer is equipped with the standard accessories or as provided for by the customer’s specification.|
The fluid generally referred to as “insulating oil” serves two purposes:
The mineral oil used with the TTO transformers complies with IEC rules, is free of PCB and PCT and is carefully dried to guarantee optimal dielectric performance. The mineral oil is inflammable so the oil transformers should be used in compliance with the local regulations.
Fire risk may be minimized by using silicon oil according to IEC60836 or a synthetic ester base such as MIDEL7131®. This fluid is biodegradable and non-hazardous, safe for use even in the most ecologically-sensitive areas.
|The lid is bolted to the tank , the seal is secured by a suitable rubber gasket or sintered material. The tank is realized by an undulated sheet, which allows the oil to expand and the heat generated by the transformer to disperse. The manufacturing process, including the bending and the welding of steel sheets, is totally robotized and all tanks are carefully tested at the end of the cycle for hot oil tightness. Severe life tests are periodically carried out on the different types to ensure the body resistance to fatigue cycles (expansion and shrinkage) deriving from the thermal dilation of the oil. The body bottom is also reinforced by bent sheet shapes used as skid for the bidirectional wheels connection.|
The internal parts are cleaned and varnished with hot oil resistant products. The body, lid and other metal parts are carefully sanded and painted with a water monolayer varnish which combines excellent performance over time with environmental protection.
The final average thickness is no lower than 120 microns.
Special painting cycles for chemical aggressive environments, cycles with increased thickness/hardness for sandy environments or hot galvanization are available on request.
All transformers are tested at our test room with routine tests in compliance with IEC60076, that is:
All kinds of type tests and special tests indicated by regulations can be carried out at the customer’s request:
Archive of type tests
SEA has a large archive of type and special tests carried out on many transformers delivered to customers worldwide. The archive is available at all times for our customers to consult.
Room temperature and load conditions
TTO oil transformers have been designed to supply nominal power in a standard distribution network under conditions defined by IEC 60076 rules.
Heights over 1000 meters, room temperatures higher than 40 °C or specific network or load conditions (presence of overvoltages, harmonics, overloads…) cause dielectric, mechanic or thermal stress to the transformer which has to be considered during design in order to not compromise its reliability and duration.
Electrical equipment must be secured against dangerous contact. The only live parts under voltage of an oil transformer are the MV and LV bushings. Transformers equipped with IP00 bushings should be segregated inside a wall or grid cell to prevent accidental contacts.
The cell should enable a proper air exchange (at least 4,5 m3/minute of air for every kW of losses) and be sized in order to allow the inspection and maintenance of the transformer. There should be at least 400/500 mm of free space all around the transformer.
TTO transformers are immersed in insulating liquid. As they can be used outside within the most difficult industrial environments and their price is competitive, SEA TTO Transformers represent the ideal solution for every industrial installation.
They are available in versions with an oil conservator or hermetic type with integral filling which requires less maintenance because the oil does not come into contact with the air. They are usually filled with PCB and PCT-free mineral oil.
TTO transformers may also be ordered with greater fire safety silicon oil filling IEC60836 or a synthetic ester-based filling such as MIDEL7131®. This fluid is biodegradable and non-hazardous, safe for use even in the most ecologically-sensitive areas.
TTO transformers have a flexible body with an undulated sheet enabling the oil to dilate during the normal thermal cycle of the transformer.
SEA TTO transformers comply with the IEC 60076 standard.
On request, transformers in compliance with other international Standards or with the Customer’s specifications may be manufactured.
Our standard catalogue covers up to 20000kVA and for the conditions of the standard:
Our design and manufacturing capacity may satisfy the most diverse needs (autotransformers, applications for converters, for traction, for testing rooms, etc...) and extend the potential application of TTO transformers to all those other sectors where a custom design is required.
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