The Complete Guide to Power Transformer Diagram

When it comes to transformers, it is fairly common to hear power transformers, which is why this article will be focused on the power transformer diagram and as well as the different types of transformers including step-up transformers.

Moreover, it is important to discuss the parts of a transformer as well.

In this article, DAELIM, one of the best power transformer manufacturers in the world, will provide you with all the necessary information needed for you to understand what power transformer diagrams are all about.

But first, it is also crucial that you learn the fundamentals of a transformer first before we go through the power transformer diagrams so that you will not be confused as we go deeper into the article.

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What are Transformers in General?

So before we go through what are power transformers, you should know first what is a transformer in general so that you can easily understand the different types of transformers in this article.

Basically, a transformer is a piece of electrical equipment that works on the principle of induction. In simpler terms, transformers are used to transmit electrical energy from a specific voltage level to another voltage level.

The first transformer existed in the early 1880s and of course, it was not as functional compared to modern transformers. However, it was very impressive that the manufacturers in that era managed to create an operating transformer.

As time passed by, transformers were continuously modified by starting with size (since the first few transformers were enormous). The first commercial use of the transformer was used a few years later.

What are the Different Types of Transformers?

In today’s generation, there are a lot of types of transformers that have been developed with different functions, parts, and operating principles.

Nonetheless, you will be able to easily comprehend all of these aforementioned matters as we go deeper into the article.

To begin with, these are the differences between a single-phase transformer and a three-phase transformer.

Single-phase Transformer

A single-phase transformer is a type of transformer that belongs to the category of power transformers that is used for single-phase alternating current or A.C. This means that this type of transformer heavily depends on a voltage cycle that works in a unified time phase.

Basically, the ratio of the primary windings to the secondary windings will determine the change in the current.

pole-mounted transformer and single phase transformer
pole-mounted transformer and single phase transformer

Three-phase Transformer

On the other hand, a three-phase power system is utilized for cost-effectiveness, because compared to single-phase transformers, it cost more money to operate and maintain. But in terms of size, single-phase transformers are easier to transport since they have a smaller and lesser weight.

The Three Phase power system is used due to its cost-effectiveness over the Single Phase Transformers. However, looking at the size and the ease for transportation, the Single Phase Transformers are suitable.

Moreover, these are further divided into core types and shell types.

Core Type

A core type is basically a type of transformer that has both of its windings placed on the side limbs. Furthermore, core type transformers mainly have two magnetic circuits.

Shell Type

On the other hand, shell-type transformers only have one magnetic circuit and winding and they are placed on the central limbs of the transformer.

This type has one magnetic circuit and winding is placed on the central limbs of the Transformer.

Oil-type Transformer

Oil-type transformers are basically transformers that use oil as their cooling medium. Moreover, transformer oil or mineral oil is known to be the most effective cooling medium for transformers.

Oil-type Pad mounted transformer
Oil-type Pad mounted transformer

Dry-type Transformer

Contrary to oil-type transformers are dry-type transformers, this type of transformer makes use of forced air or pressurized air as their cooling medium. This means that dry-type transformers are not flammable. However, this does not mean they do not have their own advantages and disadvantages.

10 kv Three Phase Epoxy-resin Dry-type Transformer
10 kv Three Phase Epoxy-resin Dry-type Transformer

Step-up Transformer

You might have heard about step-up transformers and step-down transformers which are basically two types of transformers that have the ability to increase or “step-up” the voltage levels from low to high.

Moreover, step-up transformers are of great help when it comes to voltage fluctuations because this type of electrical device is capable of stabilizing the power and supply and distributing them at normal levels.

Step-down Transformer

On the other hand, step-down transformers are the complete opposite of step-up transformers, and they basically step down voltage levels from transmission levels to distribution levels for consumer use (e.g., homes, buildings, etc.)

Indoor Transformer

As the name suggests, indoor transformers are transformers that are safe to operate inside establishments. For instance, dry-type transformers are considered indoor transformers since they can practically be placed inside buildings.

Moreover, they are used for office and residential purposes.

Outdoor Transformer

Outdoor transformers on the other hand are transformers that are not safe for indoor allocation, mainly because they are flammable since they have mineral oil or transformer oil inside them, which can easily cause fire and even an explosion if triggered.

Distribution Transformer

A distribution transformer is another type of transformer that is commonly used around the world.

Moreover, these transformers are commonly used for residential and commercial purposes since they have an efficiency level with 50% fill load capacity, and they have the ability to operate for 24 hours as well with an excellent regulation for voltages.

Instrument Transformer

An instrument transformer is a type of transformer that involves current transformers and as well as potential transformers that are commonly used to reduce the voltage.

Moreover, these transformers are capable of providing electrical isolation between high voltage power circuits and as well as measuring instruments.

Pad-mounted Transformer

Pad-mounted transformers are basically distribution transformers that are sealed in a metal housing that has a shape of a large locker that is earthed on the ground with a pad sitting beneath it.

This transformer is also considered a public transformer since it is commonly found in public areas and even in front of houses.

Single Phase and Three Phase Pad-mounted Transformer From Daelim
Single Phase and Three Phase Pad-mounted Transformer From Daelim

Pole-mounted Transformer

Pole-mounted transformers are also another type of transformer that is considered a public transformer since it is safe to be placed in public areas.

However, this type of transformer is mounted on a utility pole, which means that it is an above-ground transformer.

Two-winding Transformer

A two-winding transformer is used in applications that depend on the ratio of the voltage. Two winding transformers are known to be used with a ratio that is greater than 2 while the latter is operated at the time of voltage ratio that is less than 2.

Auto-winding Transformer

An auto-winding transformer is an electrical transformer that only has a single winding. The “auto” prefix refers to the single coil that is acting independently without any automatic mechanism involved.

Autotransformers also have the same winding act, having both the primary and secondary winding sides of the transformer.

What are Power Transformers?

Now that you know the different types of transformers, it is time to move on to power transformers and their power transformer diagram.

The main purpose of power transformers is to stabilize power voltage fluctuations which are used during high power load durations.

However, power transformers are not limited to this function only as they too have several functions and abilities.

Transformer Working Principle

The transformer itself works on Faraday’s law of electromagnetic induction and mutual induction principle. Based on Faraday’s law of electromagnetic induction, this will cause the magnetic flux to change electromotive force in the secondary coil that is associated with the core that has a primary coil.

Power Transformer Diagram

A power transformer’s diagram involves trading voltages for currents in a circuit while it is not affecting the totality of the electrical power. This means that it will take high-voltage electricity with a small current to change into low-voltage electricity with a large current, or vice-versa.

What are the Parts of a Transformer?

Transformers have several parts in them, and depending on what type of transformer it is, it could have several unique parts of functions with them.

Below are the common or main parts of a transformer.

Transformer Core

A transformer core is responsible for providing a magnetic path to channel flux. This is essential
for reducing the no-load losses of the transformer. Moreover, the core is a source of heat in the transformer that increases in size.

This is the reason why cooling ducts are necessary within the core for the purpose of regulating the temperature. So, basically, a transformer’s core creates a path for the magnetic flux.

Primary WInding

As mentioned before, transformers have two windings, and the first winding is called a primary winding.

The primary winding is the coil that draws power from the source, while the secondary winding is the coil that is responsible for delivering the energy to the transformers or changed voltage to the load. This means that it will receive and input from an alternating source.

Secondary Winding

The role of the secondary winding is to receive energy from the primary winding. Afterwards, it will be responsible for conveying it to the load.

The voltages will be produced across each of the secondary winding after it is determined by the turns of the ratio being shown.

Power Transformer Advantages

In this election, you will learn the benefits of having a power transformer, which will be a great determiner of factors for your purchase decision.

Below are the main advantages of power transformers:

Has the Ability to Increase and Decrease Voltages

When it comes to the ability of power transformers in terms of stepping up or stepping down voltages, this electrical device is known to be efficient for that purpose.

It has the ability to increase and decrease alternating current voltages, currents, or independence.

Highly Efficient

Another advantage of power transformers is that it is highly efficient for high-frequency ranges. This means that you won’t have to worry about any malfunction or misoperation as it can do fine on its own during operation.

Prevents Flux Leakage

Flux leakage is common on other types of transformers but the power transformer diagram prevents this from occurring which is definitely a great feature to have.

Excellent Mechanical Strength

In terms of the mechanical strength of power transformers, you won’t have to worry about malfunctions or misoperations because power transformers are basically designed to operate for long hours with a steady performance.

However, you should do regular maintenance on your power transformer to maintain it in good condition and to extend its longevity.

Some transformers have been known to last for more than 70 years taken care of in the right way.

Power Transformer Disadvantages

In terms of the drawbacks of power transformer, there are a few that you should consider before making a purchase decision.

Wastage in Current Flow

Due to the material of the power transformer’s iron core, there is a slight chance that there will be wastage in the current’s flow.

High Temperature

During the operation, you can expect that the transformer will produce a lot of heat the requires cooling. This will create a break in the flow of the current.


Transformers can indeed be noisy once they start operating.

For instance, dry-type transformers are known to be noisy due to the forced air or pressurized air that is in the transformer that is making the parts of the transformer bang against one another – making metal-clanging noises.

Nonetheless, this should not be a big deal if you have your power transformer placed in a remote location or an area where there are no people, buildings, or houses nearby.

Final Thoughts

There is without a doubt that power transformers are versatile electrical devices that can handle large projects for commercial, industrial, or business use. However, make sure to consider some elements first before getting one (e.g., location, permits, passing standards, etc.)

If you have any questions or clarifications with regards to the power transformer diagram, please do not hesitate to contact DAELIM’s team of professionals for immediate assistance.

About Bin Dong

Hello, I am Bin, General manager of Daelim which is a leading transformer manufacturer. If you have problems when you are looking for the equipment, what you need to do is tell us.

Custom Power Transformer

When you need to find more than just existing transformers, Daelim’s Transformer Service Center can help you design and produce distribution transformers that meet your unique needs.

We have our own factory and a professional team of engineers, which can design and modify application requirements that meet all your conditions.

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