There are countless Residential pad-mounted transformer types out there that exist with different functions. In terms of size, shape, design, build, and other features, it has its unique attributes as well.

But in this article, DAELIM, one of the top electrical companies in the world, will educate you on everything you need to know about one of the most common transformers today, which is the Residential pad-mounted transformer.

But first, how does a transformer work and what is it? The answer to these questions will help you digest the information that will be presented to you as we go deeper into this article.


What is the Concept of a Transformer?

Transformers are electrical devices that are capable of doing much work. Basically, it is a versatile electrical device that is commonly used in electrical companies to provide electricity. Furthermore, there are several kinds of transformers out there that is not only limited to such feature.

Transformers are capable of many operations including transferring electric energy from one alternating circuit to other circuits and this can be transferred to one or more circuits. This is done by increasing or reducing the voltage levels. This is also known as “stepping up” and “stepping down”.

Selection Method of Distribution Power Transformer

220KV Class Three Phase Two Winding NLTC Power Transformer

How do Transformers Actually Work?

As aforementioned, transformers are capable of doing many and different operations, which makes you question – how does it work?

Transformers can reduce conventional power circuits for the purpose of using low-voltage devices. This could be as simple as an iron, speakers, TV, and many more. Furthermore, transformers can be used to raise electric generators for electricity to be transmitted even in long distances.

When it comes to the scientific explanation of how transformers work, they work or change voltage under the influence of electromagnetic induction. For instance, as flux lines or magnetic lines build and collapse with changes in the current that is passing the primary coil, you can expect the current to be induced in another coil, which is the secondary one.

How do other Transformers work?

Let’s take air-core transformers as an example, they are specifically made to transfer radio-frequency currents like currents that are used for radio transmissions and they primarily consist of two coils, and it can also be more than one, and they are around in a solid insulating substance or an insulating coil form.

On the other hand, iron-core transformers serve analogous purposes in the audio-frequency range aspect.

Other kinds of transformers have similar working principles as well but have unique attributes.

What are Residential Pad-mounted Transformers?

Residential pad-mounted transformers are basically ground-mounted transformers that are specifically designed to supply electricity to multiple houses. Moreover, they are distribution transformers that are locked in a steel cabinet that is mounted on a concrete pad.

Residential Three-Phase Pad-mounted Transformers
Residential Three-Phase Pad-mounted Transformers

What is a Pad-mounted Transformer?

Pad-mounted transformers can usually be found in public, but they are not as common as pole transformers. Pole transformers are basically those barrel-looking electrical devices that you see on utility poles in the streets.


For starters, they do not have the same function as pad-mounted transformers. In fact, pad-mounted transformer specifications alone are already very different. The same goes for the size and appearance as well. 

Pad-mounted transformers are basically transformers that sit on a pad that looks somewhat like a wide metal cabinet or locker. Overall, their appearance is nothing alike compared to power transformers and distribution transformers.

How does a Pad-mounted Transformer Operate?

This type of transformer is commonly called either a padmount or pad-mounted transformer, which once again, is basically a ground-mounted electric power distribution transformer that looks like a wide metal cabinet since it is locked in a grounded metal housing.

Residential pad-mounted transformers are suitable for places that do not have the luxury of space, wherein a fenced enclosure is required. They are commonly used with underground distribution lines as well that are specifically located at service drops for the purpose of stepping down the primary voltage that is inlined with the lower secondary voltage that is supplied to utility customers.

Although they are called Residential pad-mounted transformers, this does not mean that they are only made for providing electricity to several homes, because this type of transformer will do fine in providing electricity to one house only.

Residential pad-mounted transformers have power ratings that range from 15 to 5000-kilovolt amperes, and this also depends if you have a single-phase pad-mounted transformer or a three-phase pad-mounted transformer.

But the majority of pad-mounted transformers have elbow connectors that are operated if they are only energized. This can be done if there is a hot stick, which allows convenience when it comes to regular maintenance.

What are Single-phase Pad-mounted Transformers?

Single-phase pad-mounted transformers are exceptional Residential pad-mounted transformers that are usually rated between 10-220 kVA that are designed to be compatible with various applications, which means that even though they are single-phase pad-mounted transformers, they still meet A.N.S.I and N.E.M.A standards,

Single-phase pad-mounted transformers may be filled with mineral oil or better known as transformer oil, and even fire-resistant environment FR3 fluid.

Take this DAELIM Single-phase Pad-mounted Distribution transformer as an example:

Single-Phase Pad-Mounted Distribution Transformer from DAELIM

All transformers from DAELIM are expertly crafted for security purposes and the best experience for the customers. When it comes to the DAELIM Single-phase Pad-mounted Transformer, it is far from the performance of generic or unbranded single-phase pad-mounted transformers.

DAELIM has made this electrical device with the necessary upgrades in order to satisfy the user’s needs such as friendly price, the right size, versatility, longevity, enhanced kV rating, and many more attributes that are upgraded.

If ever you do not have a distribution room to place it indoors, the DAELIM single-phase pad-mounted transformer can be placed indoors. So, if space is a problem, then you won’t have to worry about that with this transformer.

However, if you are planning on using it indoors, make sure that it passes the fire code of the building you are using it in since this transformer contains oil that is highly flammable. When it comes to placing it outdoors, there will be no problems with that also.

single-phase pad-mounted transformers have green belts with them for safety purposes. The green belt helps protect the public in the event that there is a malfunction in the single-phase pad-mounted transformer.

Overall, the DAELIM single-phase pad-mounted transformer is a great electrical device that can be shipped in whatever enclosure you may want it to be in. In terms of shipping, DAELIM offers both water and air shipment of all locations for your convenience. There is an abroad team that is ready to assist you as well.

But what about three-phase pad-mounted transformers? Are they any better?

Daelim Single Phase Pad Mounted Distribution Transformer warehouse
Daelim Single Phase Pad Mounted Distribution Transformer warehouse

What are Three-phase Pad-mounted Transformers?

On the other hand, when it comes to three-phase pad-mounted transformers, they are still compact power centers that are commonly used for industrial applications, commercials, and other utilities. They are also designed to be durable in order to sustain itself against harsh environments since it is exposed outside.

You can find three-phase pad-mounted transformers inside and outside buildings for the purpose of energy efficiency and safety precautions.

Since three-phase pad-mounted transformers are considered fluid-filled transformers or electrical devices, they have a wide variety of configurations which means that they can be paired with many accessories for an upgrade or to meet the necessary specifications.


Three-phase Pad-mounted Transformer Working Principle

For starters, three-phase pad-mounted transformers start operating when a primary voltage goes in the cable that is specifically designed to resist high voltages. The voltage will then be passed to the H1-A bushing then onto the transformer’s windings to the side of the Z bars.

After passing through the side of the Z bars, the voltage will then go through the connection points that exits the cable for it to go through its final destination. In terms of electrical distribution to houses, this will serve in the range of 220V to 240V.

Why do Pad-mounted Transformers have many Terminals

It is not common for pad-mounted transformer connections to come in many numbers. In fact, this is common among loop-fed pad-mounted transformers. The reason why it has many terminals is for it to be powered by two medium-voltage circuits.

What can you Find in the Inside of a Pad-mounted Transformer?

Just like typical distribution transformers, these transformers are always loaded with mineral oil, which is why it is commonly found in public areas since mineral oil does not pass the fire codes of most buildings.

In terms of their core and coils, they are sheltered in a tank that is oil-filled and made out of steel with terminals for the Residential pad-mounted transformer to be made accessible in an adjacent lockable wiring cabinet setting. 

It is also expected that the wiring cabinet has both high and low voltage wiring compartments for versatility.

inside Three phase pad–mounted transformer
inside Three phase pad–mounted transformer

How much do Residential Pad-mounted Transformers Weigh?

Normally, Residential pad-mounted transformers weigh about 800lbs which is why when installing or replacing a pad-mounted transformer requires a truck with a hook in order to lift the transformer and put it into its place.

How long do Residential Pad-mounted Transformers Last?

Transformers themselves are known to last very long due to their strong build and design from material to the main structure of the transformer.

Residential pad-mounted transformers have an expected life span of more than 30 years. In fact, even Residential pad-mounted transformers are still operating for more than 50 years! This means that when it comes to their longevity, you won’t have to worry about them wearing out any time soon.

Are Residential Pad-mounted Transformers Safe?\

In terms of passing by or standing near a Residential pad-mounted transformer, it is completely safe since there are no scientific pieces of evidence that standing near a transformer will pose an electrical health risk to you unless you accidentally bump into one.

However, for the security of pedestrians, Residential pad-mounted transformers should always be closed and locked with warning signs all over their metal enclosure. The installers will make sure there is at least 10 feet of clearance at its opening side to avoid disruption and easy access to the transformer.

A space of 5 feet for the sides will allow the space to maneuver in the case that a dangerous phenomenon occurs.

What is a Residential Pad-mounted Switchgear?

Residential pad-mounted switchgear is specifically designed to meet the requirements of the switching and isolating features of the electrical distribution system, and this goes along with 15 pre-engineered switching configurations.

Can Residential Pad-mounted Transformers Explode?

Similar to the question of Residential pad-mounted transformers, they are not if not disturbed by outside elements. However, when it comes to the device catching fire that leads to an explosion, it is possible.

This could also happen for various reasons such as lightning strikes, an animal tampering with the transformer, water getting in the windings, and many more.

These are rare instances but Residential pad-mounted transformers are equipped with safety fuses as well to mitigate the damage.

Final Thoughts on Residential Pad-mounted Transformers

There is without a doubt that Residential pad-mounted transformers are essential to the community. This is the main reason why DAELIM manufactured several variants of Residential pad-mounted transformers.

If you are looking for a transformer that is easy to operate, compact, durable, and with excellent longevity then a Residential pad-mounted transformer is a great choice for you. Whether it is for multiple houses or only one, this pad-mounted transformer will perform outstandingly.

If you have any questions or clarifications, do not hesitate to contact DAELIM’s team of professionals for immediate assistance.

Custom Residential Pad-mounted 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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