750 kVA Transformer Introduction
As we all know, the three basic technical data for power transformers are rated capacity (kVA), input voltage (V/kV), and output voltage (V/kV). To some extent, the size of power transformer depends on the capacity of the transformer, and different capacity of transformers are using in different electricity usage scenarios.
750kVA is not a big capacity for power transformers, and can be designed as different types by the professional engineer team from Daelim Belefic. Today let’s learn about different designes, and detailed techniacl informaiton of 750kVA transformers. Let's check out today's article and find more information about 750kVA transformers.
Usually, transformers with a capacity of 630kVA and below are collectively referred to as small transformers; transformers with a capacity of 800~6300kVA are called medium transformers; transformers with a capacity of 8000~63000kVA are called large transformers; transformers above 90000kVA are called extra-large transformers.
750kVA is between small transformer & medium transformer, usually used in the projects with small electricity demand. Such as: apartment, small office building, small solar farm, etc... In the situation that one building doesn’t have such electricity demand, the engineers will put several smaller transformers for each building, and the total capacity can also get to 750kVA.
Daelim had a project experience in Dominica, which has 7 apartment builidng and will need total 600kW of electricity. The project was hold by a Canaidan company, and their engineer’s solution was purchasing 7 units of 150kVA pad mounted transformers, one transformer for one building, use them to handle the total 750kVA electricity demand.
Also in the same logic, if you have a bigger electricity demand, such as 7500kVA, but the location is hard to install a 7500kVA substation transformer, then you can try 10 units of 750kVA transformers to handle the 7500kVA electgricity demabd.
Reading more about Daelim Pad Mounted Transformer
Based on the project needs, there are different types of power transformers. A professional transformer manufacturer has the ability to make the correct design for customer’s needs. Such as oil immersed design or dry type design, pole mounted, pad mounted, or substation design, etc...
For 750kVA transformer, it should be three phase design transformer, because the biggest capacity of single phase transformer is 167kVA (pole mounted design) and 250kVA (pad mounted design).
And three phase design transformer with the rated capacity of 750kVA, can be designed to oil immersed transformer or dry type transformer.
Oil immersed design transformer is immersed with transformer oil as cooling liquid. Usually the manufacturer will use mineral oil as transformer oil, the has better production cost, and PCB free. Oil immersed transformer can do distribution transformer design or pad-mounted transformer design. There are 2 types of mineral oil: Type I can work in the ambient temperature from -25℃ to +25℃; Type II can work in the ambinet temperature from -45℃ to +45℃. Type I mineral oil can use in the regions with mild climates, such as Texas, Mexico, Philippines, Africa, etc... Type II mineral oil are usually used in high latitudes, such as Canada, Alaska, Russia, and North Europe, etc...
There are another transformer oil which is vegetable oil, the cooling system of transformers with vegetable oil is called KNAN/KNAF, with mineral oil is called ONAN/ONAF. Compared with mineral oil, the vegetable oil has higher burning point, which comes higher safty, and the vegetable oil is environmental friendly.
The detailed advantages of vegetable oil are as below:
Vegetable oil is another kind of high flash point difficult fuel, its flash point is as high as 360 ℃, and it has excellent chemical and electrical properties. As a high-quality transformer insulating oil, it can eliminate the risk of fire to the greatest extent, so that the transformer can be installed in the place where it is needed without worrying about the heavy, heavy elements and dangerous high ignition point and difficult fuel oil.
Vegetable oil is a true food grade seed oil, non-toxic. It does not contain any petroleum, halogen, silicon and other substances, and can be rapidly and completely biodegraded. As a transformer oil, vegetable oil is truly green and environmentally friendly.
With vegetable oil, customers can:
• Savings on initial cost or total cost of ownership without compromising reliability.
• Extends transformer insulation and transformer life.
• Optimize load capacity.
• Significantly improved fire safety.
• Reduce environmental impact and improve environmental performance without worrying about a stable and continuous supply of materials.
With these advantages, comes higher cost than mineral oil. If the customer required vegetable oil as transformer oil, we can offer 2 options: ENVIROTEMP FR3 from Cargill brand; or Vegetable oil from Chinese brand.
Cargill FR3 oil is international famous brand, with locacl factory in China, and has higher cost than Chinese local oil brand; For Chinese brand vegetable oil, our supplier has UL certification and has better price than Cargill brand.
Dry type transformer design is also workable for 750kVA. Compare with oil immersed transformer, dry type transformer has advantages as below:
Dry-type transformers are often used in places with high performance requirements, such as fire protection and explosion protection, due to their strong short-circuit resistance, low maintenance workload, high operating efficiency, small size, and low noise.
1). Safe, fireproof, pollution-free, and can be directly operated in the load center;
2). Adopt domestic advanced technology, high mechanical strength, strong short-circuit resistance, small partial discharge, good thermal stability, high reliability and long service life;
3). Low loss, low noise, obvious energy saving effect, maintenance free;
4). Good heat dissipation performance, strong overload capacity, can increase capacity operation when forced air cooling;
5). Good moisture resistance, suitable for operation in high humidity and other harsh environments;
6). A complete temperature detection and protection system can be installed on dry-type transformers. It uses an intelligent signal temperature control system that can automatically detect and display the working temperatures of the three-phase windings, automatically start and stop the fan, and set alarms and trips;
7) . Small size, light weight, small footprint and low installation cost.
If the customer choose dry type design for 750kVA transformer, they can also add the protection cabinet for their dry type transformer.
According to the different use occasions of dry-type transformers, the cabinets of dry-type transformers can be divided into two types: indoor transformer cabinet and outdoor transformer cabinet.
The protection cabinet of the dry-type transformer placed in the room is divided into different surface mixes according to the different protection objects. In order to prevent the entry of solid foreign objects with a diameter greater than 12mm, or the intrusion of small animals such as mice and hares, the dry-type transformer casing placed indoors is usually IP20 standard, which can be used as a safety barrier for the live part of the dry-type transformer to ensure dry-type transformers. The good operation of the type transformer is not interrupted. In order to prevent water dripping within an angle of 60° from the vertical line, the housing of the dry-type transformer placed indoors is usually IP23 standard. However, the IP23 standard enclosure will reduce the heat dissipation capacity of the dry-type transformer, which means that to ensure the normal operation of the dry-type transformer, its capacity must be reduced.
The casing of the dry-type transformer placed outdoors is required to be able to prevent water dripping within an angle of 60° from the vertical line because it is used outdoors. The IP23 standard casing is the most suitable choice. But like this standard enclosure for dry-type transformers placed indoors, it reduces the heat dissipation capability of the dry-type transformer.
Whether the dry-type transformer shell is placed indoors or outdoors, its essence is to isolate the dry-type transformer from the outside world. Therefore, it can effectively prevent personnel from being too close to the dry-type transformer, thereby avoiding electric shock accidents for personnel and ensuring personnel safety.
At the same time, since the dry-type transformer is protected by the casing to avoid being directly exposed to the natural environment, the dry-type transformer can be effectively protected from damage by natural factors. Such as being washed by rain, wind and sun, etc., the dry-type transformer is prone to spontaneous combustion, and the setting of the casing can prevent the dry-type transformer from being damaged by rain, wind and sun to a certain extent, thus delaying the dry-type transformer due to long-term damage. The time is exposed to the natural environment and damaged, and the operating life of the dry-type transformer is improved.
Based on different design, the transformer dimensions are also different. Before confirm the order, Daelim can offer reference drawings to the customer; after confirm the order and receive the advance payment, Daelim engineer team will start to work on the production drawing with detailed dimensions, then send to the customer for final confirmation; if everying is confirmed the customer, we will ask for a signature on the drawing and start to produce based on the confirmed drawing.
With over 15 years of international trnasformer business experience, Daelim team will support you with the most suitable transformer solution and competitive price.
The characteristics of cast resin dry-type transformers, which are pollution-free and environmentally friendly, meet the needs of modern economic development, so they have developed rapidly in recent years.