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.

Pad-mounted Transformer

We can provide you single phase and three phase pad mounted transformer

Dry-type Transformer

Type:Cast resin; Rated Capacity: Up to 25MVA; Rated Voltage: Up to 36KV;

Pole Transformer

TypeCSP type Frequency: 50/60Hz; Rated Power: 5~167kva

Dry-type Transformer

Frequency: 50/60Hz Rated voltage:10kv, 20kv,30kv Rated Power: 400~2500kva


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”.

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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 pad mounted transformers are essential components in the electrical distribution system, designed specifically for residential areas. These transformers are installed on a concrete pad and are used to step down high voltage electricity to a level suitable for homes.

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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.

The pad-mounted transformer is a compact, complete set of power distribution devices composed of high-voltage, power transformers, low-voltage, and electric energy metering devices combined in one or several boxes. Compared with traditional substations, it has. It has the advantages of flexible combination form, short construction period, low operating cost, and small footprint. It is manufactured in a factory and does not require complicated on-site installation.

Therefore, Pad mounted transformer is widely used in the power supply system of residential quarters.

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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?

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Advantage of Pad mounted transformer

Package element includes sophisticated domestic innovation and products, featuring a galvanized steel plate outside and a durable, corrosion-resistant frame constructed from common container products. The internal securing plate is crafted from light weight aluminum alloy gusset plate, while the interlayer is composed of fireproof insulation material, guaranteeing no rusting for 20 years.

Package is outfitted with a temperature control and dehumidification system that can operate properly in extreme temperatures ranging from -40 to 40 degrees Celsius, despite outside environment conditions or air pollution. The primary equipment inside package includes cutting-edge residential modern technology such as a system vacuum cleaner button cabinet, dry-type transformer, and vacuum cleaner breaker with a springtime operating device. This item includes a fully shielded framework without subjected live components, ensuring no threat of electric shocks. In case of a crash, the station can be run safely without the requirement for oil. The secondary devices is incorporated with a digital automation system, allowing unmanned operation.

Solid architectural options

Pad mounted transformer embraces the component technique in structure, and each Pad mounted transformer can be made up of the list below kinds.

The kind of high-voltage switch attached to the power grid is divided right into ring network kind, double power supply type, and incurable kind;

According to the sort of built-in transformer, it is split right into oil-immersed completely secured transformer and dry-type transformer; according to the product of the box shell, it is split into the metal shell and non-metal covering kind;

The option of high-voltage switch determines its category, that includes gas-producing lots button, pressed air load button, vacuum tons button, and SF6 tons button. Furthermore, the switch can be further classified as intelligent or small, depending on whether it can be configured with an intelligent system.

The layout of the high-voltage room, transformer space, and low-voltage space is generally prepared in a consecutive fashion, with the high-voltage space situated prior to the transformer area, adhered to by the low-voltage area. This layout permits convenience of setup, website choice, operation, and assessment, thanks to its small and well organized framework.

Organizing transformers with each other in a dedicated area takes full advantage of efficiency and benefit.

How to choose Padmount transformer?

The pad-mounted transformer is readily available in two styles: European and American. The European version uses adaptability in its style, permitting the transformer and low and high voltage switchgear to be integrated in a solitary room, with the choice to house one or multiple transformers. Users have the liberty to choose from different high and low voltage elements, cabinet types, and transformer designs to match their demands.

If the devices stops working, it is easy to replace, yet the quantity is also big, the heat dissipation is intricate, and the price is high. The American Pad-mounted transformer is generally based upon the transformer. The load switch and fuse are set up in the oil tank of the transformer to form an integrated plan. The volume is only one-third of the European Pad-mounted transformer of the exact same capacity, and the rate is just half of the European Pad-mounted transformer.

Given that the oil container of the transformer belongs to the real estate of the Pad-mounted transformer, the warm dissipation problems are great. After a detailed contrast of technology and economic climate, a Pad-mounted transformer is favored in metropolitan network reconstruction. The selection of the capacity of the Pad-mounted transformer substantially affects the general financial investment advantage.

Intelligent configuration of Padmount transformer

The portable design of the Padmount transformer requires a high level of combination in the automation style of the gadget to understand features such as communication, fault discovery, remote control, telemetry, remote signaling, and reactive power settlement. It requires to embrace a smart system incorporating protection and monitoring. The execution of the circulation automation system is naturally included right into the circulation automation system.

The fundamental configuration consists of:

(1) The existing accuracy of the a/c tasting of the analog information acquisition and processing tool ought to go to least degree 1.0.

(2) Fault indicator feature A mistake sign with signal output is set up on the side of the 10kV inbound and outbound lines, and the signal is published to the interaction unit. The power supply and circulation dispatching facility assess the fault point.

The tool needs to be capable of acquiring and refining digital quantities, consisting of catching the required information and preserving it temporarily when an instantaneous signal is produced by a mistake sign. In addition, it should include an automatic recuperation system.

(4) Communication function: It utilizes GPRS or CDMA cordless communication modern technology to interact with the dispatch center and sends telemetry and remote signaling.

The capacitor is changed automatically based upon the connection between voltage and responsive power by the responsive power compensation feature.

Power supply methods for single-phase Pad mounted transformers

The following single-phase Pad-mounted transformer power supply techniques are available, tailored to satisfy the differing requirements of customers and the dependability demands of different houses:

The chain power supply mode contains the power circulation terminal or exterior ring network closet, high-voltage cord branch box, and ring network type single-phase Pad-mounted transformer.

The advantage of this power supply approach is that each single-phase Pad-mounted transformer has two power materials, and the power supply reliability is high;

However, a disadvantage is that the high-voltage cord is lengthy, the cost is somewhat elevated, the functional process is somewhat intricate, and settling the interlacing problem between both power sources is essential.

The power supply mode of this single-phase Pad-mounted transformer is suitable for the single-phase Pad-mounted transformer to provide power to users with dual-circuit power supply demands.

For example, in a residential area, the high-voltage power supply line is single-phase and is attached to the A, B phase, B, C stage, C, and A phase with 2 single-core cables or two-core wires. The Pad-mounted transformer makes use of 2 T Type bushing + elbow-type cable television plug for ring supply link, play the role of four-way, specifically connect to the inbound line, loophole line, outward bound line, arrester position, and set up a two-position low-voltage tons switch at the outward bound line setting to connect or Cut off the load brought by this single-phase Pad-mounted transformer or replace the two-position load button with an elbow-type cord plug and double fuse defense. Plug and unplug straight.

(2) A trunk-type power supply configuration is established by incorporating either the power circulation terminal or the ring network closet, the high-voltage cable branch box, and a single-phase Pad-mounted transformer of ring network type or terminal kind with a two-position low-voltage tons button.

The attribute of this power supply setting is that the power circulation station or the ring network closet outputs a single-channel power supply to the high-voltage cable television branch box. The incoming line is a three-phase kind, and the outward bound line is a single-phase kind. In A, B, B, C, C, and A phases, the outgoing circuit is regulated within six circuits, and each circuit does not surpass 3 single-phase Pad-mounted transformers. The overall variety of single-phase Pad-mounted transformers carried by each branch box is. The variety of systems will not surpass 18 systems.

The very first two single-phase Pad-mounted transformers in each outgoing line are ring network kind, and the last one is terminal kind.

The benefit of this technique is that it can be attached in collection with 3 Pad-mounted transformers that are closest to the actual distance on-site, conserving the investment of high-voltage cable televisions; the downside is that there is only one power supply, and the power supply integrity is less than that of the chain power supply technique. Power individuals.

The radial power supply system consists of a power distribution station, an outdoor ring network cabinet, and a ring network or terminal kind single-phase Pad-mounted transformer with dual fuse defense (no-load switch). This setup enables effective power distribution and trusted security against electric mistakes.

The power distribution station runs in a dual-power supply mode, offering both a primary and backup two-way power supply to the outdoor ring main device. The power is then distributed to the outside ring primary unit, excluding the high-voltage cord branch box, and is further divided right into 3 single-phase outgoing lines. Each line is outfitted with a Pad-mounted transformer, with a maximum of 3 transformers per circuit. The first two transformers in the middle are of the ring network kind, while the last one is a terminal type.

This technique provides the benefit of having the ability to attach three Pad-mounted transformers in series, which are located near the real distance on-site, thus reducing the investment in high-voltage cables. In addition, the exterior ring network cabinet flaunts a two-way power supply, giving both the benefits of a chain-type power supply technique and a trunk-type power supply method. The two power supply techniques offer enhanced power supply integrity compared to the trunk-type technique, while needing much less financial investment than the chain-type approach. This approach is especially appropriate for suburbs with multi-story buildings, such as those located in municipalities, demolition and resettlement areas, and so on.

The box covering is made from galvanized steel plate and container manufacturing innovation, and the appearance layout is beautiful, under the facility of guaranteeing the dependability of the power supply.

Picking a covering shade for the Pad mounted transformer that matches its surroundings enables an unified mix with the atmosphere.

Utilized in densely inhabited locations such as urban residential quarters, it can be used as both a fixed substation and a mobile substation, which not just does not impact the control and improvement of the environment yet additionally has the impact of decorating and beautifying the environment.

Practical and perfect features, adaptable circuitry, very easy upkeep or replacement

The power supply needs of different neighborhoods can be met making use of the ring network or terminal. This setup allows for easy conversion, boosting the reliability of the power supply and reducing the influence of specific tools breakdowns. Repairing or replacing a single-phase Pad-mounted transformer does not require it to be lifted with a pole or positioned on a bench. These transformers are lighter than three-phase ones and do not require large building and construction equipment for maintenance or substitute, making the process quicker, more convenient, and reducing repair time substantially.


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.

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 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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