Structure and operation principle of a 3-phase transformer

Three-phase transformer: Construction and It's Working

A power transformer is important equipment in the electrical system. It is used to transmit and distribute electricity for consumption. You must have a machine with a large enough capacity to meet the needs of transmission of power over long distances. That's why a 3-phase transformer was born.

So what is a 3-phase transformer? And what's the structure of it? Let's explore the article below.

Table of contents

1. What is a Three-phase transformer?

2. Structure and operation principle of a Three-phase transformer

a. Structure of a 3-phase transformer

b. Operation principle of a 3-phase transformer 

3. Some types of 3-phase transformer

a. Closed-type 3-phase transformer

b. Open-type 3-phase transformer

c. Dry transformer

4. Price list for three-phase transformers

1. What is a Three-Phase Transformer?

A three-phase transformer is a static electromagnetic device made to transmit energy or send alternating electrical signals between circuits through Faraday's electromagnetic induction phenomenon. 

Three-phase transformers play an important role in the power transmission system. This equipment is mainly used for industrial purposes to generate, transmit, and distribute electrical energy. Three-phase transformers are used and installed in places that consume an extremely large amount of electricity such as buildings, apartments, hospitals, power stations, etc...

2. Structure and operation principle of a Three-phase transformer

a. Structure of a 3-phase transformer

The structure of a three-phase transformer consists of 3 main components:

  • The steel core is one of the main components of a 3-phase transformer. The steel core of a 3-phase transformer has three magnetic pillars to wind the wire and the magnet to close the magnetic circuit. The machine's steel core is made from electrical engineering steel sheets, two sides covered with insulating paint, and assembled together into a cylinder shape.           
  • Three-phase machine winding has six copper windings that are insulated, wrapped around the cylinder. The winding is used for receiving energy in and transmitting power out during machine operation.
  • Transformer enclosures are also quite important, helping to protect and maintain the circle life of the transformer. Usually, the shell of a 3-phase transformer is made of plastic, iron, steel, etc. depending on the structure of the machine and each 3-phase transformer manufacturer, they will be had a different structure.

Inside of 3-phase Transformer

b. Operation principle of a 3-phase transformer 

The operation principle of a 3-phase transformer is very simple, 3-phase transformers will operate based on two physical phenomena :

+ Electric current flows through the generated wire magnetic field

+ The flux variation in the coil of the conductor produces an induced voltage
When you understand the principle of the machine's operation, you will quickly grasp the operating procedure and principles to ensure the efficient working of 3-phase transformers and the correct capacity of the device.



3. Some types of 3-phase transformer

Normally, Transformers will be classified based on voltage classes, the core used, the layout and location of winding. Below we list the most commonly used three-phase transformers on the market today:

  • Sealed type 3-phase transformer
  • Open-type 3-phase transformer
  • Dry-type 3-phase transformer

a. Sealed type 3-phase transformer

Sealed type 3-phase transformer cooled through expansion blades. When the temperature is high in the VH, these blades will expand themselves; the air blowing directly through the blades helps the machine cooler. 


Closed-type 3-phase Transformer

b. Open-type 3-phase transformer

The open-type 3-phase transformer has a cooling cycle through the auxiliary oil tank and the fan blade. The difference between open-type and sealed type is the extra oil tank.


Open-type 3-phase Transformer MBT

c. Dry transformer

Dry-type transformers, also known as molded plastic transformers, are transformers with coils wrapped in epoxy resin. Unlike conventional transformers, the windings and magnetic cores of a dry transformer are pressurized by air. Dry transformers were born to overcome the disadvantages of oil transformers. Dry transformers are used in special conditions such as heavy environmental pollution, air humidity higher than 95%, ambient temperature down to - 25 ºC.

MBT - Dry 3-phase transformer

Related articles:

What is a power transformer? 

Purpose of using a transformer

4. Price list for three-phase transformers

A three-phase transformer is the flagship product of MBT Electrical Equipment Joint Stock Company (MBT). Our company is proud to be the leading manufacturer and supplier of prestigious distribution transformer in Vietnam with more than 20 years of experience in the field of transformer research and production with a team of staff. The company's employees are highly qualified; the market has highly appreciated modern technology equipment and machines, the company's products and services. 

With four factories of over 20000m2, MBT provides a full line of products from 1-phase transformers, sealed type 3-phase oil transformers, open-type transformers, dry transformers, etc... Up to now, the number of transformers that MBT has exported to the market has reached more than 50,000 units. In addition, there are other product lines such as medium-voltage and low-voltage switchboards, kiosks, single-column integrated power stations, voltage stabilizers, AC and DC reactors, etc...

With the business motto: "Quality Nurtures Reliability " - When coming to MBT, customers will always receive high-quality products, reasonable prices, the fastest delivery time, and the best warranty service.

Contact export department immediately +84913 006 538 or email: [email protected] for a free consultation and support and receive the most preferential quotation.


(+84) 0913.006.538
Skype, Telegram, Wechat ...