Ultimate 1250kVA Transformers for Guide

So you want to know about a 1250kVA transformers. But after looking for references, you’re not sure whether or not your sources have been as accurate. Don’t fret. You have come to the right place.

In this article, you will be learning about the 1250 kVA Transformer specification, ratings, uses, frequently asked questions, and other relevant topics to assist you in making a confident decision or help you learn more about this type of transformer.

We at Daelim are trained professionals and have formulated this article to help you with your needs.

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How Does 1250 kVA Transformer Work?

So, first off. How does this transformer work?

A transformer converts alternating current, or AC for short, from one voltage to another, maybe one or more.

Transformers are split into two categories: step-up transformers or transformers step-down and work on the principle of magnetic induction.

A step-up transformer boosts the voltage from the primary to secondary and converts low-voltage with a high current to a high voltage with a low current.

However, a step-down transformer works oppositely and provides a reduced output voltage more appropriate supply for common electronics.

All transformers have no movable parts, which means it stays still when it operates.

It works completely static, which makes the job easier. A typical transformer consists of at least two coils of insulated wire but could have more.

These coils are winded up on a laminated steel core.

The first coil induced with voltage is called the primary or input coil, which magnetizes the core.

When a voltage comes into contact with another coil, it is called the secondary or output coil.

Voltage ratio or the change in voltage between the primary and secondary will depend on the turns ratio of these two coils.

View other types:2500 kVA Transformer

What Are The 1250 kVA Transformer Specifications?

Transformers are manufactured differently. So, before buying a transformer, you need to consider that not all specifications are the same.

But a typical 1250 kVA Transformer specification include:

  • 1250 kVA Rated Capacity
  • 2 Coils
  • Three-phase type
  • 50 Hz Frequency
  • 13.8KV Primary Voltage
  • 480v Secondary Voltage

Phase Type

Transformers are also categorized by phase, single-phase, and three-phase types.

A single-phase transformer transfers AC power from the input coil to another coil at a constant frequency and voltage level variation.

Transformers have two windings, being the primary winding and the secondary winding.

The primary winding draws power from the source, while the secondary winding transports the energy at the set voltage ratio to the power load.

A three-phase supply works differently.

These transformers are primarily utilized for power generation, distribution, and transmission for industrial purposes.

It costs less to construct multiple single-phase transformers to build a three-phase transformer than purchasing a single three-phase transformer.

The three-phase transformer connection can be made by Star (Wye) and Delta (Mesh) type.

1250 kva substation transformer

Oil-Immersed vs. Dry-Type Cooling

Cooling modes are also a factor you need to consider when buying a transformer.

The most substantial difference in these transformers is that dry-type transformers use air for cooling while oil-filled transformers use oil.

A dry-type cooling mode is cooled with natural or forced air cooling.

You can use the transformer continuously for extended periods in this cooling mode.

With forced-air cooling, the output capacity of the transformer could increase by half, which is ideal for operating intermittent overload or emergency overload.

Different types of dry-type transformers are used at most public places as the oil-filled ones are susceptible to catching fire, which is why they are commonly used outdoors where leakage wouldn’t cause a significant hazard.

But you will notice that dry-types are more frequently used and typically found in transportation hubs and offices.

In terms of cost, oil-filled transformers are more affordable compared to dry-type ones because they function on traditional energy efficiency, providing reliability and longevity.

Dry transformers use more power and have a high operating loss, leading to additional costs. However, the cost isn’t that big of a difference.

1250kva Oil-Immersed transformer

Core Design

The design of transformer cores affects a transformer’s efficiency.

Cores consist of legs and yokes, which support the coils, and upper and lower yokes connect the legs.

Additionally, the ends of the laminations used to make the core are commonly cut at a 45° angle instead of a squared angle, allowing the layers of the legs and yokes to overlap slightly and improve the magnetic conduction path.

Current Ratings

Kilovolt-Ampere or KVA is used to determine the 1250 kVA Transformer current rating.

Higher KVA ratings mean higher power production.

To get a decent kVA rating, you will need a transformer that outputs the right kVA.

Where To Use 1250 kVA Transformers?

Regardless of kVA, you can use transformers outdoors or inside buildings.

Transformers are commonly found in an electrical room or other areas within a building.

They are divided into a few classifications: Low Voltage, Medium Voltage, and High Voltage.

Low voltage transformers have rectifiers that assist in converting the output into Radio Frequency Interference (RFI) and Direct Current (DC).

Keep in mind; transformers offer a variety of configurations.

Compared to low voltage transformers, medium voltage transformers need larger power and are in their category.

This transformer also has a limited voltage capacity, just as others do.

A high voltage transformer needs to be remotely controlled or manually placed on-site to properly test and maintain individual power supply systems.

It can have high-voltage windings or high-voltage isolation, and when it comes to phases, it can be single-phase, three steps based.

1250kva transformer used in bitcoin miner

Can Transformers Be Used As Crypto Power?

Transformers can be used for Bitcoin mining power systems.

The first element in your mining power supply is a transformer to supply power to your whole rig, and designing a power system for a Crypto mine can be daunting.

Transformers take medium voltage from a substation and convert it to low voltage, sufficient power for mining.

Purchasing numerous 1000kVA or 2000kVA breaker panels rather than a single large one is typically far more cost-effective.

Which of these voltage combinations is the most effective?

Because it is not the most efficient voltage, 240V or 415V is the most recommended.

It is the most cost-effective arrangement to put together.

Single-pole circuit breakers may be used in your breaker panel or switchgear, and the ability to employ smaller breakers in terms of current is a big benefit.

1250 kva transformer for bitcoin mining farm

Why Would A Transformer Leak Oil?

Oil leakage is bound to happen one way or another.

And this is commonly caused by corrosion or faulty welds, which leads to the breakdown of seals, fins, valves, flanges, and pipework.

If your transformer is leaking, there’s a moisture and contamination risk which compromises your transformer’s insulating qualities.

The classic repair technique takes the transformer out of service, drains the oil, removes radiators, removes bushings, etc.

What Happens When A Transformer Runs Out Of Oil?

If a transformer leaks mineral oil, it can easily start a fire.

Fire codes often require that transformers inside buildings use a less-flammable liquid or use dry-type transformers with no liquid at all.

To answer the question, if the oil level goes below the top of the windings and exposes the wire, they will lose the oil’s cooling benefits.

The lower the oil, the less cooling, and the more the upper, exposed windings are likely to overheat.

What Is The Life Expectancy Of High-Voltage Transformers?

Transformers operate for around 30 to 40 years, while industrial transformers have a life expectancy of merely 20 to 25 years under ideal conditions.


It is recommended to ensure that the area for your transformer could easily ventilate air.

A cooling and ventilation device must be added when the transformer is installed in the basement or a poorly ventilated environment.

The fan air cooling system has low noise, uniform cooling, and good effect.

It’s small, consumes little space, and doesn’t overextend the outline size of the body.

If you have any problems and need more assistance, consider contacting our experts at Daelim Electric Co.

You will never go wrong when consulting a trained professional to help you with your problems.

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.