Dry Transformer: The Ultimate FAQs Guide - Daelim
The transformer industry manufactures different transformers, each with unique capabilities and features that serve different purposes. One such transformer is the dry-type transformer. Daelim's array of dry-type transformers provides many advantages, making them the preferred choice for many applications.
This Frequently Asked Questions guide will answer some common queries regarding this type of transformer to understand further what dry transformers are.
What is a Dry transformer?
A dry transformer is an electrical transformer that uses air or gas as an insulation medium instead of liquid. It is also sometimes referred to as an air-core transformer. Dry transformers are very different from their liquid or oil-filled counterparts.
For one, dry transformers are more efficient and durable than oil-filled transformers because there is no liquid to leak or catch fire. Additionally, dry transformers are easier and cheaper to maintain because there is no need to check or change the oil periodically.
Dry transformers are also smaller in size and lighter in weight for a given power rating when compared to an oil-filled transformer of the same rating. This is due to the fact that dry-type transformers use thinner wire coils which take up less space.
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What is the Use of a Dry Transformer?
Dry transformers are static devices that use air as a cooling medium. When the unit heats up during the conversion from higher to lower voltage, the air and the Dupont Nomex insulation material used in the construction of the transformer, work together to dissipate the heat.
Dry transformers are typically used in indoor applications where there is no risk of the unit being exposed to water or other liquids. However, they are also used in locations where there is a high risk of fire, such as in chemical plants or oil refineries.
Dry Type Transformer Standards
The energy performance standard for dry transformers are as follows:
Single Phase KVA Rating:
15kva at 97.70 1.2 kV Class
25kva at 98.00 1.2 kV Class
37.5kva at 98.20 1.2 kV Class
50kva at 98.30 1.2 kV Class
75kva at 98.50 1.2 kV Class
100kva at 98.60 1.2 kV Class
167kva at 98.70 1.2 kV Class
250kva 98.80 1.2 kV Class
333kva
500kva
667kva
833kva
Three-phase KVA Rating:
15kva at 97.89 1.2 kV Class
30kva at 98.23 1.2 kV Class
45kva at 98.40 1.2 kV Class
75kva at 98.60 1.2 kV Class
112.5kva at 98.70 1.2 kV Class
150kva at 98.83 1.2 kV Class
225kva at 98.94 1.2 kV Class
300kva at 99.02 1.2 kV Class
500kva at 99.14 1.2 kV Class
750kva at 99.23 1.2 kV Class
1,000kva at 99.28 1.2 kV Class
1,500kva
2,000kva
2,500kva
3,000kva
3,750kva
5,000kva
7,500kva
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What is a Dry Type Distribution Transformer?
A dry type distribution transformer is a type of transformer that serves as the final stage in the electrical distribution system. It steps down the voltage from the secondary of the main power transformer to the level required by the loads.
Since it's dry-type, it uses air or gas for insulation instead of liquid or any other medium. Additionally, the unit is filled with nitrogen gas to prevent the growth of mold and mildew.
Dry-type distribution transformers can be used both indoors and outdoors. They are typically placed in a vault, on a pole, or underground. That way, they are protected from the elements and tampering.
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Dry Type VS Oil Type Transformers: What is the Difference?
When shopping for transformers, you will come across two types: dry-type and oil-type. Both transformers are essentially the same. However, the main difference between the two is their insulation method.
Dry-Type Transformer
Dry-type transformers use air or any gas-type medium for insulation. A dry-type transformer can either be self-cooled or force-cooled. This feature makes dry-type transformers more expensive than oil-type transformers because the latter relies on the natural convection of air to cool itself, requiring less maintenance.
Oil-Type Transformer
On the other hand, oil-type transformers use a liquid insulation medium, typically mineral oil. The oil is used to cool the transformer and prevent the build-up of heat. As a result, oil-type transformers are less expensive than dry-type transformers.
However, they require more maintenance because the oil needs to be changed periodically. Additionally, oil-type transformers are a fire hazard since the oil is flammable. However, they are far more efficient and durable than dry-type transformers and can last for decades with proper maintenance.
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To understand how both of these transformer types perform, let's take a look at the differences between them:
Cooling Medium
Dry-type transformers use air as a cooling medium, while oil-type transformers use liquid, typically mineral oil.
Maintenance
Dri-type transformers require less maintenance than oil-type transformers. That's because they don't require regular oil changes and there's no risk of leaks.
Oil-type transformers also require testing for chemical contamination, which only adds to the maintenance costs. On the other hand, dry-type transformers are chemically resistant and don't require this testing.
Operational Costs
With what has been said so far, it's understandable to assume that oil-filled transformers have higher running costs than dry transformers. However, it's the exact opposite of that belief.
Though it requires regular maintenance, oil-filled transformers are less expensive since they use conventional energy efficiency. This makes them longer-lasting and more dependable.
On the other hand, dry transformers have a shorter lifespan and are not as efficient. As a result, they have higher operational costs.
Recyclability
Oil-filled units have a much easier core recycling process than dry type. However, the recycling process of dry-type units is more restricted, complicated recycling types that are not as common. This makes it difficult to find a facility that can do it.
Efficiency
Dry-type transformers are efficient, but not as much as oil-filled transformers. This is because dry transformers are much larger and have a lower voltage rating. Unfortunately, this means the dry transformer types are more prone to overheating during an overload, which results in a higher maintenance cost and electrical loss. Fortunately, since they don't tend to overload often, efficiency is not as important of a factor.
Location
The location is considered the most significant consideration when choosing a transformer type. For example, if the installation is outdoors or dusty or wet, then dry-type transformers are the better option. That's because they're designed to withstand harsh conditions.
On the other hand, if the installation is indoors in a clean and dry environment, then an oil-filled transformer is the better option. They're more efficient, have a longer lifespan, and require less maintenance.
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What are the Advantages of a Dry Type Power Transformer?
Better Overload Capacity
Dry-type transformers can handle overloads better than oil-type transformers. That's because the windings in a dry-type transformer are cooled by the surrounding air, preventing them from overheating.
Low Partial Discharge
Partial discharge is a phenomenon that causes insulation degradation in transformers. There are tiny gaps or voids in the insulation that allow for a small discharge of electricity.
This ultimately causes the transformer to fail. On the other hand, dry-type transformers are less likely to experience partial discharge because the windings are surrounded by a solid material that doesn't have any gaps or voids.
Can Be Fitted Outdoors
Another advantage of dry-type transformers is that they can be fitted outdoors. That's because they don't rely on a liquid insulation medium, so they are not at risk of leaking. For that reason, you can fit dry-type transformers outdoors inside an IP-45 enclosure without any issue.
Zero Risk to Fire Hazard
Since it uses nonflammable air as winding insulation, a dry-type transformer doesn't pose a fire hazard. In contrast, oil-type transformers are a fire hazard because the oil used for insulation is flammable.
Non-Hygroscopic
Dry-type transformers are also non-hygroscopic. That means they don't absorb moisture from the air, which can cause corrosion. That's why dry-type transformers are ideal for outdoor applications since they can withstand the elements better than oil-type transformers.
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Can Dry Type Transformers Be Used Outside?
Yes! Dry-type transformers can be used both indoors and outdoors because of the following features:
It's non-flammable
It's not hygroscopic
It can be fitted inside an IP-45 enclosure
They are typically placed in a vault, on a pole, or underground. That way, they are protected from the elements and tampering.
How Are Dry Transformers Cooled?
Dry-type transformers are cooled in one of two ways: self-cooling or forced cooling.
Self-cooling is the most common cooling method, and it's used for small to medium-sized transformers. The surrounding air cools the transformer, so they are often fitted with fans to circulate the air.
Forced cooling is used for larger transformers that generate more heat. The transformer is cooled by a liquid, typically water or oil. The liquid is circulated to the transformer to remove the heat.
How Do You Protect a Dry Transformer?
Dry transformers can make use of different shells and enclosures to protect them from the environment and from tampering. However, it will depend on the environmental aspect and the transformer's size and power rating.
The IP-20 protective casing prevents the entry of foreign objects bigger than 12 millimeters in diameter. This level of protection provides solid safety for the live parts inside the dry transformer.
The most common type of enclosure is an IP-45 enclosure. This type of enclosure is made of sheet steel and fitted with a door that seals the transformer inside. The IP-45 designation means that the enclosure is dust-tight and protected against water jets.
If you're installing the dry transformer outdoors, then the IP-23 and IP-54 levels of protection are suitable since they are ideal for use in damp or wet conditions. In addition, these protective enclosures prevent water ingress which could cause damage to the transformer.
The IP-65 level of protection is the highest, and it's used in hostile environments. This type of enclosure is made of stainless steel and it's fitted with a door that seals the transformer inside. In addition, the IP-65 designation means that the enclosure is dust-tight and protected against water jets.
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What's the Efficiency of Dry Type Transformers?
The energy efficiency of dry-type transformers is available in 35% nominal load and 50% nominal load. The efficiency of a transformer at 35% nominal load is typically 99.5%. The efficiency of a transformer at 50% nominal load is typically 99%.
What is a 1000 KVA Dry Type Transformer?
A 1,000 kVA dry type transformer is a large, expensive electrical device that converts high-voltage electricity into lower voltages. These devices are usually found in power plants and substations, where they are used to step down the voltage of electricity before it is sent to homes and businesses.
What is the 2000 KVA Dry Type Transformer Price?
A typical 2,000 KVA Dry type transformer has an average price of $24,425.52. However, the price can vary depending on the features and specifications of the transformer. That's why most transformer manufacturers like us at Daelim offer transformers on a quote basis. This way, the customer can get a more accurate price for their specific needs.
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What is a 2000 KVA Dry Type Transformer?
A 2,000 kVA dry type transformer is a type of transformer that uses air as a cooling medium instead of liquid. At the same time, it also uses a power rating of 2,000 kVA or higher. These types of transformers are mostly used in industrial applications where there is a need for high power capacity.
What is a Three-Phase Dry-Type Transformer?
A three-phase dry-type transformer is a self-cooled transformer that uses two windings and is available in a wide range of primary and secondary voltage combinations. These units are mostly used in industrial applications where there is a need for high power capacity. In addition, since it's a three-phase transformer, it works on a three-phase power supply, with both primary and secondary windings having three total sets of windings.
What is a 33KV Dry Type Transformer?
A 33kV dry type transformer is a high-voltage device known as an epoxy resin-cast transformer. Unlike traditional dry-type transformers, it uses epoxy resin as an insulating material. The higher and lower voltage windings are made from copper foil (strip) and cooled with epoxy resin. This type of transformer is mostly used in outdoor applications where there is a need for high power capacity.
What is a 500 KVA Dry Type Transformer?
A 500 kVA dry type transformer is a large, expensive electrical device that converts high-voltage electricity into lower voltages. These devices are usually found in power plants and substations, where they are used to step down the voltage of electricity before it is sent to homes and businesses.
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Best Dry Type Transformer Manufacturers
Daelim is one of the best dry-type transformer manufacturers because we offer different high-quality transformers suitable for various applications and industries. We also provide a wide range of services, such as installation, maintenance, and repairs.
Daelim has been in the transformer business for years, and our experience and expertise are unrivaled. Daelim offers a wide range of dry-type transformers, such as air-cooled cast resin transformers.