PRODUCTION PROPERTIES
Winding
Copper or aluminum is used as conductor in low voltage windings. The windings are made of sheet, rectangular section paper or nomex coated insulated wire. If the windings are made of sheet, shellac paper (DDP) coated with resin with increased thermal value strength is used as layer insulation. In high voltage windings, copper or aluminum conductor is used again according to customer request. The bobbins are wound with computer controlled fully automatic machines. The special structure of floor insulation increases the resistance against impact voltage; The insulation class is class A as general acceptance. Depending on customer requirements, production is made in B, F, H and C class insulation levels.
Nucleus (Cores)
The cores of the transformers are made of cold rolled, grain oriented siliceous sheets. The cores are produced using first class quality sheets. The core sheets selection is made according to the idle loss values requested by the customer. The Sheets is sliced, sorted and lined with George machines without burrs. The cores are produced with or without step-lap, over-lap, 90º, 45º cut holes.
Active Part and Cover
The core, coil and top cover assembly is designed to increase resistance to short-circuit forces. The top cover covering the active parts of the standard transformers is mounted to the tank with bolts. Another application is the installation of the active part directly into the tank. The connection parts of the top cover, high voltage insulators and arc horns are made of stainless steel or rust-resistant, special paint-coated materials. Insulators (bushings), accessories, protection box or cable box can be placed on the cover or on the boiler side walls of the transformer according to customer request.
Tank
Tanks and top covers are made of St 37.2 steel. Base plate, sides and frame are sealed. Radiator is used as cooling surface. After welding, each tank is subjected to oil tightness test. Welded tanks and top covers are sandblasted in accordance with DIN standards. It is possible to add protective and covering cable boxes to BS 2562 in IEC 60144.
Painting
The transformers are in RAL 7033 color as standard. Transformer tanks are sprayed and sprayed. Dyeing method and color are selected according to customer requirements and transformer operating conditions. For example, C1 - C2 - C3 - C4 - C5 - I - C5 - M grade paints suitable for corrosion protection H2S may be applied. ELTAŞ A.Ş. company We can offer transformer with different film thickness or different colors in different applications (zinc plated) according to customer request. In addition, hot-dip galvanized tanks can be manufactured if desired.
Drying and Oil Filling
The active part of the transformers (core, coil, cap) is dried in the ovens under precise vacuum. The drying process depends on the type, power and voltage of the transformer. Oil filling is done under precise vacuum.
The main accessories used to protect the transformers are as follows.
- Oil Level Indicator
The magnetic oil level indicator is used to monitor and control the oil level in the expansion tank. Magnetic oil level indicator gives alarm and trip signal in case of sudden changes in oil level.
- Air Dryer
Air dryers are used in transformers with expansion tanks. The air dryer is connected to the expansion tank. With the help of silica gel, moisture and dust are kept in the expansion tank. The amount of silica gel depends on the amount of oil in the transformer.
- Oil Temperature Display
The oil temperature gauge placed in the thermometer pockets welded on the lid or on the sides of the tank monitors and controls the top temperature of the oil. It can be with maximum indication, without electrical contact or single or double electrical contact. If the temperature exceeds the estimated values, the contact thermometers give an alarm or trip signal.
- Buchholz (Gas collection and Alarm) Relay
The Buchholz relay collects gases generated by low and high intensity discharge and arcs within the transformer. It is used in transformers with expansion tanks. The relay can be single or double contact. If a certain amount of gas is collected in the Buchholz relay, it activates both the alarm and the trip signal. In addition, the Buchholz relay emits an alarm signal at a low oil level. The Buchholz relay detects faults such as overheating and signals to prevent the failure from growing.
- Pressure Relief Valve
Even if a hermetic protection relay is used in transformers, a pressure relief valve is also used. The pressure relief valve serves to relieve the rising pressure in the transformer.