Complete Guide to 3 Phase Transformer

3 phase transformer

The primary function of a transformer, including a 3 phase transformer, is to step up or down the power generated at the power plants. After that, they distribute the power towards substations and other consumer units. You can say that the main function of a three phase transformer is to increase or decrease the AC voltage. It also helps in keeping the power output and its frequency at a constant level.

While discussing power transfer, we need to remember that a DC power transformer has some pretty decent advantages over AC power transmission despite having too much cost. However, due to certain advantages, the DC is used to transport from power plants to households or factories. After reaching the factories or houses, the DC power is later converted into AC current to provide power to appliances.

What are 3 phase transformer?

3 phase transformer is the three different 1-phase transformers integrated into 1 single circuit. In simpler terms, three inductive coils are set to wrap around a single core. This is done in different configurations such as Delta – Delta (Δ-Δ), Delta – Star (Δ-Y), Star Delta (Y-Δ), Star – Star (Y-Y), and so many different arrangements. The sequence and configurations of these arrangements are chosen based on the power requirement.

Let’s discuss some more interesting facts about 3 phase auto transformer:

These types of transformers generally have a set of primary as well as a second set of windings. These two different sets are connected in Delta or Star connections.

  • As we previously mentioned, a 3 phase transformer is basically an integrated circuit where 3 different 1-phase transformers are built together. This allows the transformer to take on and maintain a heavy load while preserving the electrical line.
  • The primary set of windings are connected to 7200V US & 11KV in the United Kingdom and Europe. Other than this, in the United States, both 1 phase and third phase of the transformer provide 120V and 240 V, 277V, and 480V.
  • A 3 phase power transformer provides power supply via three phases and a Neutral Wire (3L+1N).
  • A three phase transformer can provide both one phase electricity as well as three phase electricity.
  • There is no requirement to provide or connect any kind of extra device to the three phase power supply to the one phase transformer. This is because it has a built-in system for that as well.
  • Due to the three systems integrated into the one-single system, the power supply, as well as the capacity, is higher in the three phase conductors.
  • The cost, as well as the size of the 3 phase isolation transformer, is both greater and bigger simultaneously.
  • The electrical power transmission is way higher than the one phase transformer due to the integration of three circuits.
  • One of the distinctive advantages of these transformers is in case a power line becomes faulty due to any number of reasons. The power supply won’t stop since there are two other phases working perfectly fine.
  • The primary role of these transformers is to supply power from power plants to industrial areas and commercial applications.


Applications of 3 phase transformer

  • The applications of 3 phase isolation transformers are so many. Let’s take a look at a few of them to get a better understanding of their importance.
  • Since, a three phase transformer can further exempt any number of high-frequency noise, as well as pulse interference from the coupling of the one phase transformers. These are generally used with precision machine tools.
  • In addition to this, all three phase transformers are widely used in industries, mining, factories, production companies, textile, printing, packaging, airports, telecommunications, malls, multistory apartments, office equipment, and many more.
  • All the transmissions, as well as the distribution of the tunnels and equipment are secured to confirm the standard voltage.
  • In addition to providing all the benefits of three phase transformers, they are also great at offering the benefits of one phase transformers. This makes the range of the benefits of the three phase auto transformer wider.



There are many pros and advantages of using three phase transformers over one phase transformers. Some of them are lesser weight or mass when compared with single phase transformers. While others have smaller sizes than single phase transformers for easy installation as well as cost. The invention of three phase transformers was a miracle for humanity. It has made industrialization way smoother and more efficient than we had imagined.