Basic Guide To Oil Immersed Transformer
Nov 11, 2025
Leave a message
What is oil immersed transformer?
The oil-immersed transformer has three-dimensional wound iron core has no air gap in its magnetic circuit because its three core columns are three-dimensionally arranged in an equilateral triangle, and the winding is tighter, the three magnetic circuits have the same length and the shortest, and the cross-sectional area of the core leg is closer to a circle, so the performance is further improved, the loss is reduced, the noise is reduced, the three items are balanced, and the third harmonic component is reduced. But since the pressure regulating switch is inside the tank. The contacts of the switch are not visible from the outside when adjusting the pressure. There are two reaction phenomena: if the contact is not good, the circuit is broken. If the contact is not good, it is easy to burn the switch when the load is too large.
The oil-immersed transformer is an important piece of equipment in power systems, it is mainly used to change voltage and transmit electrical energy. Oil-immersed transformers work mainly on the principle of electromagnetic induction. It is suitable for power grid transformation of urban and rural, industrial and mining enterprises, and more suitable for combined transformers and transformers for prefabricated substations.
Operating temperature of oil transformer
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.
Oil type transformer vs dry type
The oil-immersed transformer is the transformer coil and core soaking in dedicated transformer oil, the benefits of this are, namely can the cooling coil can cut off from the air to prevent moisture in the air cause corrosion to the transformer's core, and the same time can also play a role of arcing, so early in our country, electric power transformer and the power switch is in the oil .
The dry transformer core and the coil as a whole, are fixed, can be directly exposed to the air, and can also be placed indoors, but the temperature and humidity requirements of the environment are very high. Its characteristics can be unattended, as long as the regular check is on the line.
The cooling medium and insulating material for their windings and other components is the use of dry-type transformers. Their main purpose and general purpose are the same as that of oil-immersed transformers, which is to adjust the primary voltage of the transformer to a level commonly used in industry, households, and businesses.
Working principle of oil-filled transformer
The oil-immersed transformer is an important power. Its main functions are becoming more and more complex, and the structure of various oil-immersed transformers is also increasing. Oil-immersed transformers can adapt to more working environments.
Oil-immersed transformers have windings, iron cores, and bushings to work together. The role of the magnetic core is to provide a path for the magnetic current. The heat of the equipment in it can be reduced. The purpose of the bushing is to connect the transformer windings to the substation.
Precautions for oil-immersed transformers
1. The building where the transformer is placed must meet the fire resistance level requirements specified in the building fire protection code;
2. In the event of a fire, measures must be taken to prevent the outflow of oil from causing the fire to spread;
3. There must be fire-extinguishing measures to extinguish oil-based fires.
Oil immersed transformer advantages
When the oil-immersed transformer in operation needs to be supplemented with oil-immersed transformer oil, the type of oil-immersed transformer oil should be determined first, and then filled with oil-immersed transformer oil of the same grade, because different types of oil-immersed transformer oil cannot be mixed at will.
If you really can't find the same oil-immersed transformer oil and really need to add fashion, you should first understand the oil-immersed transformer oil, the physical properties of the oil-immersed transformer oil you want to add, such as density, viscosity, freezing point, flash point It is closed, and then the stability test, two oil samples, according to the needs, the ratio of the mixture in the container for one month, observe whether there is any change, such as no deposits found in production, and meet the standard oil-immersed transformer insulating oil, you can use.
GNEE Oil Transformer Product Parameters
| Items | Item |
| Production Descriptions | Oil-Immersed Transformer |
| Reference standards | IEC 60076-11 |
| Capacity | 50-2500kVA or Customized |
| Frequency | 60 / 50Hz |
| Voltage (HV) | 22KV or customized |
| Voltage (LV) | 0.4KV or customized |
| Impedance | 4% |
| Connections (Vector Group) | Dyn11 |
| Tapping Range | ±2×2.5% |
| Core materials | Silicon Steel |
| Winding materials | Aluminum or copper |
| Lightning Impulse Withstand Voltage | IEC standard |
| AC withstand voltage | IEC standard |
| Temperature Rise class | H-class |
| Temperature Rise | 125K |
| Cooling method | AN/AF |
| Delivery Capacity | 300 units per month |
company profile
GNEE TRANSFORMER has strong production capacity and an efficient marketing team.
Our transformer products include 500kV, 400kV, 330kV, 220kV, and 110kV ultra-high voltage transformers, various dry-type transformers/oil immersed transformers/amorphous alloy transformers of 35kV and below, new energy transformers, and prefabricated substations,
Export series: single-phase transformer, three-phase transformer, cylindrical transformer, isolation transformer, control transformer, voltage regulator and other products, And various specifications of special transformers such as grounding transformers, arc suppression coils, Bitcoin transformers, prefabricated cabins, reactors, electric furnace transformers, rectifier transformers, mining transformers, marine transformers, etc.
GNEE TRANSFORMER has successively passed ISO9001, ISO14001, ISO45001, SA8000 system certification. At the same time, 10kV and 35KV level distribution transformers and box type substations have obtained interna- tional Electrotechnical Commission IEC certification, US UL certification, German TUV certification, EU CE certification, Dutch KEMA certification, and GOST certification. Our product sales cover the global market, including 72 countries and regions such as the United States, Europe, Canada, Mexico, etc.
transformer Workshop equipment display
types of transformer from GNEE
Get Transformer Order specification
GNEE Transformer Order specification
|
When choosing our company's products, please provide the following data to better serve you. |
||
|
Demander |
||
|
Demander: |
Telephonemethods: |
Fax: |
|
Project technical leader: |
Telephonemethods: |
Mailbox: |
|
Transformer type selection |
||
|
□Dry transformer {□SC(B) Epoxy resin □SC(B) Non-encapsulated} □American Box(ZGS) {□Terminal type(-Z-) □Ring network type(-H-)} □European Box change(YBM){□ Dry change □Oil change} |
□ Oil-immersed transformer{□ Fully sealed(-M-) □Oil-bearing pillow} □Amorphous alloy transformer{□Dry amorphous □ Oil amorphous} □ Special transformer{Rectifier, Furnace, Mine, Etc} |
|
Transformer basic data selection
|
Country of use: |
|
|
Phase number: |
□Three-phase(S conventional) □ Monophase □Other( ) |
|
Frequency: |
□50Hz(conventional) □60Hz □ Other( ) |
|
Transformer oil: |
□#25(conventional) □#45(minimum temperature below-25℃) |
|
Rated capacity: |
□( )kVA Conditions of use □Outdoor type □Indoor type |
|
Altitude: |
□Less than 1000m(conventional) □1000-2000m □3000m以上 over |
|
Rated voltage(High voltage) |
□6kV □10kV □20kV □35kV □66kV □110kV □220kV □Other( ) |
|
Rated voltage(Low pressure) |
□0.4kV □0.66kV □10kV □10.5kV □35kV □其他 Other( ) |
|
Connected group |
□Dyn11(conventional) □Yyn0 □YNd11 □li0(Single-phase) □Other( ) |
|
Impedance(%): |
□4% □4.5% □5.5% □6% □6.5% □7.5% □8% □Other( ) |
|
Voltage regulation mode |
□Voltage regulation without excitation(conventional) □On-load voltage regulation(Z) |
|
Voltage regulation range |
□±2*2.5% □±5% □±3*2.5% □Other( ) |
Transformer accessory selection
|
□Fan □Temperature control{□ Common □With 485 computer interface} □Dry case{□ Ordinary steel sheet □Aluminum alloy » Stainless steel} □Protection level of dry case(□IP20(Conventional) □IP( )} □Dry case height requirements{□None □Requirements[ ]} □ Cable out mode of the dry variable shell {□ Up-and-out □ Up-and-down □Down-in/DOWN-out □Down-in/UP-out □Down-in/DOWN-out □Down-in/ side-out [□Left □ Right-out]} |
|
Note: 1. (Dry change requirements s 100kVA transformer does not include fans, such as fans, need to be charged 2. (Oil changes <630kVA transformer does not include temperature control, gas relay, if necessary, need to increase the fee) |
Other special requirements(additional charges apply below)
|
Dry transformer |
□Shell and bottom plate{□Ordinary □Fully sealed} □Travel switch □Magnetic lo □Zero sequence transformer □Copper bar to the low voltage cabinet □Protective mesh □Lighting □100kVA or less Fan □Shock absorber |
|
Oil-immersed transformer |
□No.45 oil for non-low temperature areas □Designated brand on-load voltage regulator □400kVA and below low voltage outlet OABC phase with wiring terminals □630kVA or below requires temperature control □800kVA or below Low voltage outlet phase 0 requires wiring terminals □630kVA and below must be equipped with gas relay |
GNEE TRANSFORMER Industrial Layout
Asia:China, Philippines, Cambodia, Malaysia, Myanmar, Indonesia, Vietnam, Mongolia, Japan, Taiwan Province, Bangladesh, Sri Lanka, Lebanon, Saudi Arabia, Turkey, Armenia, Iraq, Iran, Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan
Africa:Egypt, Ethiopia, Angola, Botswana, Burundi, Cape Verde, Congo, Guinea, Ghana, Gabon, Zimbabwe, Cameroon, Kenya, Rwanda, Malawi, Mauritius, Mauritania, Mozambique, South Africa, Nigeria, Somalia, Chad, Central Africa
North America: Aruba, Panama, Dominican Republic, Costa Rica, Honduras, Caribbean region,Canada, United States, Mexico, El Salvador, Guatemala, Jamaica
Europe: Bulgaria, North Macedonia, Finland, Norway, Ukraine, Greece, Hungary, Italy, United Kingdom
South America: Argentina, Paraguay, Ecuador, Colombia, Guyana, Venezuela, Uruguay, Chile
Middle East: The Middle East region
Oceania: Australia, Papua New Guinea. Fiji