Jiangsu Yawei Transformer Co.,Ltd. is one of the leading manufacturers and suppliers of oil immersed transformer in China. Please feel free to buy high quality oil immersed transformer from our factory. Customized orders are welcome.
Single-phase
Single-phase two-column stacked iron core, single-phase single-column side-yoke four-column core, single-phase double-column stacked iron core, single-phase radial stacked iron core, etc., usually used in low-voltage, high-current or small-capacity transformers.
Three-phase
Three-phase column-type stacked iron core, three-phase side-yoke-type five-column iron core, three-phase double-frame stacked iron core, three-phase reactor stacked iron core and other structures, which can be used to raise and lower the voltage of the three-phase system at the same time.
Power transformer
Electric voltage converter can be used in various scenes of voltage increase and voltage reduction voltage power station and voltage change voltage station, comprehensive voltage station, solar power item and other power-intensive work, power voltage adjustment capacity is insufficient, and the root demand can be reduced. There is a problem with low power transportation, and we also provide long-distance power transportation solutions.
Distribution transformer
10kv-35kv or less voltage transformer is required for distribution voltage. Suitable for various types of electric power, special distribution area, suitable for large load, large load, high voltage, high stress, and high voltage. The design is robust, flexible, and has a long service life.
Hermetically sealed distribution transformer
Hermetically sealed distribution transformer is normally used in environments such as humidity, dust, ash, and corrosive gases. Because the pressure oil does not come into contact with the external air, the pressure oil does not change, and the service life of the pressure changer is extended, so this kind of pressure changer is practically free.
There is an iron core in the oil-immersed transformer, and there are two mutually insulated windings wound on the iron core. Among them, the side connected to the power supply is called the primary winding, and the side that outputs electric energy is called the secondary winding. When the AC power supply voltage is applied to the primary winding, an alternating current flows through the winding, generating alternating magnetic flux in the iron core. This alternating magnetic flux not only passes through the primary winding, but also passes through the secondary winding, and the induced electric potentials E1 and E2 are generated in the two windings respectively. At this time, if the secondary side winding is connected to the load of the external circuit, a current flows into the load, that is, the secondary side winding has power output. The ratio of the induced electromotive force of the primary and secondary sides of the oil-immersed transformer is equal to the ratio of the turns of the primary and secondary side windings. Therefore, when the number of turns of the primary and secondary side windings of the transformer is different, the voltage can be changed. Compared with ordinary transformers, its cooling method is slightly different. During the operation of oil-immersed power transformers, the heat of windings and iron cores is first transferred to the oil, and then transferred to the cooling medium through the oil.
What Is The Function Of Oil In Oil Immersed Transformers
Insulation
The first function of oil immersed transformer oil is insulation, and the insulation strength of transformer oil is much higher than that of air. Immersing insulation materials in oil can improve insulation strength and prevent moisture erosion.
Heat dissipation
The second function of transformer oil is to dissipate heat. Transformer oil has a high specific heat and can be used as a coolant. The heat generated during the operation of the transformer can cause the oil near the iron core and winding to expand and rise due to heating. Through the upward and downward convection of the oil, the heat is dissipated through the radiator, ensuring the normal operation of the transformer.
Arc suppression.
The third function of transformer oil is the arc suppression effect. On the load tap changer of oil circuit breakers and transformers, arcing occurs when the contacts switch. The thermal conductivity of transformer oil is good. Under the high temperature of the arc, it will decompose a large amount of gas, generate greater pressure, improve the arc extinguishing performance of the medium, and quickly extinguish the arc.
Components of Oil Immersed Transformer
Iron core
The iron core of the transformer is the magnetic circuit part and the skeleton of the body, which is composed of an iron core column, an iron yoke and a clamping device. The part of the jacket winding is an iron core post. The part that connects the core pillars to form a closed magnetic circuit is called the yoke. The clamping device is used to clamp the core, clamp the winding and fix the lead. The coil is fitted on an iron post, and the yoke is used to close the entire magnetic circuit. The core is made of silicon steel sheet, which has good magnetic permeability and small hysteresis loss. There are A, B, C three-phase winding on the iron core, each phase winding is divided into high voltage winding and low voltage winding, generally the inner layer around the low voltage winding, the outer layer around the high voltage winding. In order to reduce the hysteresis and eddy current loss in the iron core, the iron core is commonly made of silicon steel sheet with a high silicon content and a thickness of 0.35~0.5mm, and the sheet is coated with insulating paint.
Winding
The winding is the circuit part of the transformer, which is generally made of insulated enameled, paper-wrapped aluminum or copper wire. According to the different arrangement of high and low voltage windings, the windings are divided into concentric and overlapping types. For concentric winding, in order to facilitate the winding and core insulation, the low-voltage winding is usually placed near the core column; For overlapping windings, the low voltage winding is usually placed close to the yoke in order to reduce the insulation distance.
Insulation sleeve
The wire outlet device is the insulation sleeve, which is composed of a central conductive rod and a porcelain sleeve. The insulation bushing is the connecting part of the high and low voltage coils of the power transformer and the external line. The leads of the high and low voltage coils of the transformer are drawn from the tank to the outside of the tank, and the leads are insulated from the grounded tank. The bushing not only acts as the lead insulation to the ground, but also acts as the fixed lead. Therefore, the bushing of the power transformer must have the specified voltage strength and sufficient mechanical strength and good thermal stability. There are many forms of bushing, which can be divided into pure porcelain, porcelain oil-filled type and capacitor type according to different structures. In order to reduce the leakage caused by dust and rain, the porcelain insulation sleeve has a multi-stage umbrella shape.
Oil storage tank
The oil storage tank, also known as the oil pillow, is used when the transformer is in operation, the oil expands due to heat, the transformer stops running or the temperature decreases so that the oil shrinks, and the oil inside the transformer is always full. At the same time, the contact surface between the transformer and the air is also reduced to reduce the impact of oxidation and moisture on the transformer oil.
Heat dissipation pipe
For small capacity transformers, the heat generated by the winding and the iron core is cooled naturally through the contact between the transformer oil and the inner wall of the tank, and the contact between the outer wall of the tank and the cold air outside, without any additional cooling device. If the transformer capacity is slightly larger, the heat dissipation tube can be welded on the outer wall of the fuel tank to increase the heat dissipation area. The heat energy generated by the iron core and winding in operation makes the oil temperature rise, the volume expands and the density becomes smaller, the oil rises into the heat dissipation tube, and then the oil temperature into the heat dissipation tube decreases, the volume shrinks and the density increases, and the heat from the iron core and the winding is dissipated through the natural circulation of the oil.
Moisture absorber
There is a moisture absorber on the oil storage cabinet, which is equipped with a glass, and contains a desiccant to absorb the moisture in the air entering the oil storage cabinet.
Safe airway
The safety airway, also known as the explosion-proof tube, is a trumpet shaped tube installed on the top of the transformer, and the tube mouth is sealed with a diaphragm. Its function is that when a short circuit fault occurs inside the transformer, the transformer oil decomposing into a large number of gases causes the oil pipe pressure to be large, the safety port diaphragm is broken first, and the oil gas is ejected from it, reducing the pressure in the tank and preventing the tank from deforming or exploding due to the sudden increase in pressure.
When the oil-immersed transformer is working, it is necessary to ensure that the working temperature will not cause the transformer oil to deteriorate too quickly, thereby increasing the operating cost. When the oil at the operating temperature of the oil-immersed transformer reaches 85 degrees Celsius, it will alarm, and when the maximum temperature reaches 95 degrees Celsius, the switch of the transformer will be turned off.
Therefore, the oil temperature that specifies the operating temperature of the upper layer of the oil-immersed transformer cannot exceed 85°C. The rated capacity of the transformer refers to the maximum power allowed for long-term continuous operation when the transformer can obtain economical and reasonable efficiency and normal expected service life under the specified ambient temperature. The ambient temperature specified by the transformer is that the maximum temperature is 40°C, the maximum daily average temperature is 30°C, the maximum annual average temperature is 20°C, the minimum temperature for outdoor transformers is -25°C, and the minimum temperature for indoor transformers is -5°C.
According to operating experience and special research, when the insulation temperature of the transformer winding is in the range of 80-140 °C, the loss of insulation life will be doubled for every 6 °C increase, and the service life will be reduced by half. This is the 6 °C rule for transformer operation. The maximum allowable temperature of the transformer winding for long-term operation is the normal life temperature, and the maximum allowable value of the winding hot spot temperature is the safe temperature.
In order to make the insulating material obtain the most economical service life, it is divided into different heat-resistant grades such as Y, A, E, B, F, H, C, etc., according to its maximum allowable working temperature under normal conditions. Among them, the Y grade insulation has the highest allowable temperature The working temperature is 90°C, A grade is 105°C, E grade is 120°C, B grade is 130°C, F grade is 155°C, H grade is 180°C, and C grade is above 180°C.
How to Maintain Oil Immersed Transformer
Disconnect the low side of the circuit breaker, pull off the disconnector, hanging in the corresponding signs.
Disconnect the load switch on the high voltage side of the transformer, close the grounding knife, and complete the switch safety insurance and hang the relevant identification card.
Enter into the oil transformer room, first check whether the transformer in the power failure state, then pull the high-pressure isolation knife, check the shell, porcelain and lead with or without deformation, if there is damage should be replaced. Check the oil level, if the oil spill, should replace the pad. Check whether the silicone is effective, if there is discoloration or serious failure, should be replaced immediately.
Re-tighten the lead terminals, pins, grounding screws; If there is loosening, put on a new spring washer, fastening screw.
Check the transformer peripheral lighting, heat, dust removal equipment is intact, wipe the transformer body and porcelain dust with a clean cloth.
Check the transformer high-pressure side of the load switch to ensure that the operation is flexible, good contact, the drive section is lubricated.
Check the transformer room whether have the remaining tools, close the high-voltage side of the isolation switch, evacuate the scene.
Certifications
Our Factory
Yawei Group has more than 180 engineering and technical person , more than 1200 employees, covering an area of 240,000 square meters.
We have strong production capacity and built a highly efficient marketing team. The products include 110kvpage-3-5220kv and 500kv ultra-high voltage transformers, 35kv and below dry-type transformers, oil immersed transformers, amorphous metal transformer, wind and solar storage new energy transformers, prefabricated substation and special transformers such as reactors, electric furnace transformers, rectifier transformers,mining transformers, split transformers and phase shifting transformers of various specifications. In order to assure the implementation of the advanced design and manufactural technology,some key equipments, moulds and tools had been replaced and improved with the latest technologies to meet the requirements of product quality.
FAQ
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