[Transformer] Do you know the working principle of oil immersed transformer?
Writer： Hengfeng you electric Time：2023-04-26 views：times
Classification: It can be divided into iron core transformer and iron shell transformer. If the winding is wound on the iron core, it is an iron core transformer; If the iron core is wound on the winding, it is an iron clad transformer. But they are slightly different in structure and no essential difference in principle. All power transformers are iron core type.
The transformer is mainly composed of iron core, winding, oil tank, oil conservator, insulating sleeve, tap changer and gas relay.
1. Iron core
It is the magnetic circuit part of the iron core transformer. Hysteresis loss and eddy current loss will generate heat during operation. In order to reduce heat loss, volume and weight, the iron core adopts cold rolled grain oriented silicon steel sheet with magnetic permeability less than 0.35mm. According to the arrangement of windings in the iron core, there are core type and shell type.
In large capacity transformers, in order to make the heat generated by core loss be fully taken away by insulating oil during circulation, so as to achieve good cooling effect, cooling oil passages are often set in the core.
2. Winding
Winding and iron core are the core components of transformer. I2Rt knows that it will generate heat because the winding itself has resistance or there is contact resistance at the joint. Therefore, the winding cannot pass the current higher than the rated current for a long time. In addition, the short circuit current will generate great electromagnetic force on the winding and damage the transformer. Its basic windings are concentric and overlapping.
The main faults of transformer winding are interturn short circuit and short circuit to bushing. Inter turn short circuit is mainly due to insulation aging, or mechanical damage to insulation caused by transformer overload and penetrating short circuit. When the oil level in the transformer drops, interturn short circuit will also occur, causing the oil level of the winding to be exposed; In addition, in case of through short circuit, the winding will be deformed due to overcurrent, causing mechanical damage to the insulation, and inter turn short circuit will also occur. In case of interturn short circuit, the current in the short-circuit winding may exceed the rated value, but the current in the whole winding may not exceed the rated value. In this case, the gas protection will act, and the differential protection device will also act when the situation is serious. The reasons for short circuit to the shell are also insulation aging or oil moisture, oil level drop, or lightning strike and switching overvoltage. In addition, in case of through short circuit, the winding will be deformed due to overcurrent, and short circuit to the shell will also occur. When the enclosure is short circuited, it is usually the action of gas protection device and grounding protection.
3. Oil tank
The body (winding and iron core) of oil immersed transformer is installed in the oil tank containing transformer oil, and the oil tank is welded with steel plates. The oil tank of medium and small transformers consists of a tank shell and a tank cover. The transformer body is placed in the box shell, and the box cover can be lifted out for maintenance.
Operating principle of oil immersed transformer
The basic principle of transformer is electromagnetic induction principle. Take a single-phase double winding transformer as an example to explain its basic working principle: when voltage 1 is applied to the primary winding, current 1 flows, and alternating magnetic flux is generated in the iron core, these magnetic fluxes are called the main magnetic flux, under its action, the two windings respectively induce potential E1 and E2. The formula of induced potential is: E=4.44fN? m
Where: effective value of E-induced potential
F Frequency
N-turns
Maximum value of m-main magnetic flux
Because the turns of the secondary winding are different from the turns of the primary winding, the induced potentials E1 and E2 are also different. When the internal resistance and voltage drop are ignored, voltages 1 and 2 are also different.
When the secondary side of the transformer is no-load, only the current (0) of the main magnetic flux flows through the primary side, which is called excitation current. When the secondary side load flows through the load current 2, the magnetic flux is also generated in the iron core, trying to change the main magnetic flux.
6-35kv oil immersed transformer, 6.6kv transformer, 11kv transformer, 15kv transformer, 20kv transformer, 33kv transformer. Thirty years of manufacturing experience. Hengfengyou Electric will provide you with the best transformer solution. CB CCC UL KEMA certification. It has been exported to Uzbekistan, Pakistan, Zimbabwe, Tanzania, Ethiopia, South Africa, Kuwait, Iraq, the United Arab Emirates, Vietnam, Spain and other countries and regions. The product certification is complete. Hengfengyou Electric will provide you with the best electrical product solutions. https://www.hengfengyou.com ； info@hengfengyou.com ； WhatsApp：+86158 5325 2696（Jack） +86158 5326 5269（Alisa）
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