Archívy Blog - BEZ Transformátory

When to choose epoxy and when to choose oil transformer

12. May 2025/in Blog/by Copy Digitalman

Choosing the right transformer is not just a technical matter, but a decision that will affect its safety, maintenance and long-term operating costs. The most common types of transformers include epoxy and oil-immersed transformers. But when to choose which one? Let’s take a look at their advantages, disadvantages and the situations in which they are best applied.

What sets them apart

The oil-immersed transformer is filled with a special insulating oil that dissipates heat while insulating the internal components of the equipment.

The epoxy transformer has windings flooded with epoxy resin, it does not need any liquid, so it is often referred to as dry-type.

When to opt for an epoxy transformer

This type is ideal wherever safety, cleanliness and ease of operation are a priority. We recommend it for buildings where people move around, such as shopping centres, hospitals, schools and offices. It is used in interiors with limited space and a requirement for low noise levels, but also in places with strict fire and environmental standards.

There is no risk of oil leakage and the fire risk is also lower than that of an oil-immersed transformer. The epoxy transformer features minimal maintenance requirements and installation is simple and quick. However, the purchase price can be higher and the performance also has its limitations.

V BEZ TRANSFORMÁTORY We manufacture dry-type transformers with a capacity of up to 10,000 kVA and a maximum equipment voltage of up to 36 kV. Due to their high seismic resistance and low power losses, these devices are also suitable for harsh environments.

When to choose an oil transformer

Oil-immersed transformers offer high performance and are suitable for harsher outdoor environments. They are part of substations, energy-intensive industrial plants and locations where heavy loads or extreme climatic conditions are expected. High performance goes hand in hand with efficient cooling. With proper maintenance, the oil transformer is characterized by a long service life.

However, there is a higher risk of fire, so regular maintenance is always advisable, whether it concerns checking the oil or the filter systems. In addition, it is not suitable for confined spaces in buildings.

Company BEZ TRANSFORMÁTORY is one of the leading manufacturers of oil-immersed transformers in Central Europe with more than 120 years of history. It manufactures distribution transformers with outputs from 25 kVA to 16 MVA and with maximum equipment voltages up to 38.5 kV. They are characterized by maintenance-free operation, high reliability, the possibility of using environmentally friendly dielectrics and energy efficiency.

Quick comparison

In conclusion, both dry (epoxy) and oil-immersed transformers from our company represent the top in their category. However, the choice between them depends mainly on the specific application and operating environment.

Epoxy transformers are characterized by their high level of safety, minimal maintenance and compact design, which will be appreciated in interiors, commercial buildings, hospitals or data centers. Thanks to the advanced epoxy resin potting of the windings, they can withstand moisture, dust and vibration and do not pose a risk of liquid leakage.

On the other hand, oil-immersed transformers are superior in robustness, higher performance and excellent cooling. This makes them ideal for industrial plants or power distribution networks.

Simply put, if you are looking for a maintenance-free and safe solution for your building, choose a dry-type transformer. However, if you need high performance and operation in harsh or outdoor environments, reach for an oil-immersed one. In either case, however, you can rely on the company’s quality and experience BEZ TRANSFORMÁTORY.

With more than 120 years of history, modern production facilities and exports to dozens of countries around the world, we are one of the leaders in Central Europe. We specialize in the production of both oil and epoxy transformers that meet the most stringent technical and environmental standards. We are able to adapt our solutions to different sectors, from industry and energy to renewables and public buildings.

So if you are looking for a reliable partner in the transformer field, contact us. With us, you get a long-term partner with a strong focus on reliability, safety and lasting value.

Výmena transformátora: kedy dáva zmysel vymeniť starý za nový

Transformer replacement: when does it make sense to replace the old one with a new one

24. April 2025/in Blog/by Copy Digitalman

Transformers have a limited lifespan and therefore, if you have an older model, it may already be showing signs of wear and tear. This will manifest itself in a change in its performance, efficiency, but also in the safety of operation. The importance of transformers in the power grid is not negligible. They ensure the stability of the entire system, which raises the question of whether transformer replacement is necessary. What are the advantages of modern equipment and what options do you have for refurbishment? Is it worth more to renew and upgrade old equipment or invest in new equipment?

Each transformer has its life expectancy

Several factors affect the service life of a transformer, such as the temperature of the environment, the quality of the materials used, the intensity of operation and the method of maintenance. High loads and irregular maintenance can also shorten its lifetime, which is normally between 25 and 40 years. To minimize the risks of breakdowns, it is imperative that you carry out regular maintenance and monitor the condition.

Transformer replacement: problems associated with old equipment

As the transformer ages, there is a significant reduction in efficiency, leading to greater energy losses. This is because insulating materials and other components wear out over time. Core and winding losses increase with age. In addition, operating an old transformer often leads to higher costs. These can gradually exceed the cost of replacing or upgrading the equipment. Older transformers operate less efficiently, increasing electricity consumption, and require more frequent maintenance and repairs. Worn components increase the likelihood of failure and cause financial losses. Equipment failure can even lead to power outages. In addition, old transformers can also pose a hazard.

Advantages of modern transformers

Investing in modern transformers pays off. They can significantly improve the efficiency, safety and cost of operation of electricity networks designed to minimise energy losses. These are a particular problem in older installations. Thanks to advanced materials and optimised core and winding design, they convert electricity with much higher efficiency. New materials, such as high-quality steel, reduce core losses, which are independent of the load.

By replacing your old equipment with a new modern model, you can save significantly

New equipment requires less maintenance, reducing the cost of repairs and regular inspections. They last longer and deteriorate less.

The main benefits include improved reliability and safety of the transformers due to higher quality components, reducing the risk of unexpected faults and failures. Advanced safety mechanisms are also part of modern models. They constantly monitor the status of the equipment, and allow you to anticipate problems.

With the development of new technologies and materials, transformers are becoming more and more powerful, efficient and environmentally friendly.

By replacing your old equipment with a new modern model, you can save significantly

Transformer replacement vs. upgrading

Replacing the old transformer with a new one is the best solution in the cases described above. However, refurbishing and upgrading older equipment can also be another solution. One of the most common methods is to repair or replace worn and damaged components such as windings, contact insulation or accessories. Not all damage requires total replacement.

In older models, there are often problems with insulation materials that can be solved with modern insulation and cooling systems. Older transformers can also be fitted with advanced monitoring systems that monitor the transformer in real time and allow abnormalities to be detected before they develop into serious problems.

If you are deciding whether to refurbish an old transformer or replace it with a new one, consider several factors

If the cost of refurbishment does not exceed the value of replacing the transformer and the transformer is still in good technical condition, refurbishment may be more profitable. However, replacement is more reasonable if the cost of refurbishment exceeds the cost of new equipment. Even if the transformer is showing serious wear, replacement is often the best solution.

Transformer parts: key components and their role in electricity distribution

22. April 2025/0 Comments/in Blog/by Copy Digitalman

BEZ transformátory, it would not be possible to transmit electricity efficiently over long distances. Significant losses would occur. But what are the key components that change the AC voltage and enable the efficient transmission and distribution of electricity? What are the parts of a transformer and what is their function in operation?

Core: the heart of the transformer

The core is the key element of the transformer. It serves to conduct the magnetic flux between the primary and secondary windings, thus ensuring efficient energy transfer through electromagnetic induction. It focuses and amplifies the magnetic field created by the current in the windings. The better quality material it is made of, the more it minimizes energy losses and increases the efficiency of the transformer.

The core is usually made of thin sheets of electrical steel with an insulating layer. The sheets are layered to reduce eddy currents and hence heat loss. This material is chosen for its excellent magnetic properties – in particular low hysteresis loss and high magnetic permeability.

According to the arrangement of the magnetic flux in the core, we distinguish two basic types of core design:

Core (column) core: The windings are placed on the arms of the core and the magnetic flux passes mainly through the columns. This type of core is simpler and is often used in power applications.
Core cladding: the windings are surrounded by a core on all sides, resulting in lower dissipation losses and higher mechanical resistance. This arrangement is suitable, for example, where there are requirements for compactness and strength.

The choice of core type depends on the requirements of the specific application, such as current magnitude, voltage, dimensions and cooling conditions.

Windings: a key element in voltage transformation

Windings are among the key parts of the transformer. They are coils wound on a core and, based on the principle of electromagnetic induction, they enable the transfer of electrical energy between circuits.

Most often in the transformer we find:

Primary windingsthat receive electricity from the grid and create magnetic flux in the core.
Secondary windings that induce an electrical voltage according to the turns ratio and supply it to the output circuit.

Transformers with a more complex structure may also have a tertiary winding, auxiliary winding or balancing winding.

Windings are made of copper or aluminium conductor:

Copper ones have better conductivity, lower losses, but higher price.
Aluminium ones are a cheaper alternative, but have a larger size and higher resistance.

The insulation of the windings is also important . Different materials are used, for example varnish, paper, polyester film or epoxy resin.

Windings: a key element in voltage transformation

Windings play a key role in the proper function of a transformer because they determine the output voltage and the efficiency of power transfer. If the secondary winding has more turns than the primary, the transformer voltage increases. Conversely, if the secondary winding has fewer turns than the primary, the transformer reduces the voltage. Thus, we speak of step-up and step-down transformers.

Transformer cooling parts

Each transformer generates heat during operation. If it were not sufficiently cooled, the temperature would rise dangerously, causing, for example, insulation degradation, reduced efficiency and, in extreme cases, equipment failure. Choosing the right cooling system is therefore very important:

Olejové chladenie: Efektívne odvádza teplo a predlžuje životnosť zariadenia. Nájdeme ho vo veľkých výkonových transformátoroch v elektrárňach a rozvodných sieťach alebo priemyselných transformátoroch, kde je potrebná vysoká účinnosť.
Vzduchové chladenie: Je menej náročné na údržbu a ekologicky prijateľnejšie. Používa sa v malých a stredných distribučných transformátoroch v mestských budovách, ale aj nemocniciach, kancelárskych priestoroch a tuneloch, kde je na prvom mieste bezpečnosť. Nehrozí totiž žiadne riziko úniku oleja.

Other transformer parts important for safe and efficient operation

In addition to the main parts such as the core, windings and cooling systems, the transformer is equipped with various accessories that enhance its reliability, safety and functionality and help protect the transformer from damage. They also facilitate its maintenance and ensure proper operation:

Electrical safety is enhanced by insulators that separate the electrical conductors from the transformer carcass and prevent electrical short circuits (jumps).
Reliable power transmission is ensured by the connection terminals used to connect the transformer to the power grid.
To protect against overload, the transformer is usually equipped with a monitoring device. In the case of oil-immersed transformers, also an overpressure valve which, in the event of overload or short circuit, if not detected by other protections, will protect the transformer from damage.
The tap changers allow the output voltage to be adjusted according to the current network conditions. They keep the voltage stable and increase the efficiency of the device.
Excessive pressure inside the transformer is prevented by an expansion tank that compensates for changes in oil volume caused by temperature fluctuations.
Early detection of problems such as oil leaks or overheating is detected early by oil level and temperature indicators.

Only the proper functioning of these components will ensure safe and efficient operation. They help prevent outages, extend the life of the equipment and ensure a stable supply of electricity.

Transformer losses: why they are important and how to minimize them

11. March 2025/0 Comments/in Blog/by Copy Digitalman

Every transformer, even the most efficient, loses some energy in the form of heat. These transformer losses, small as they may seem, accumulate in the long run and lead to higher financial costs and a negative impact on the environment. Let us therefore look together at the different types of losses, their causes, and especially the methods of minimising them.

Transformer losses have a direct impact on the efficiency and cost of operation

Although transformers are designed to minimize losses, they cannot be completely avoided. However, several types of losses are known:

No-load losses occur in the iron core of the transformer. We therefore call them iron losses. They reduce the efficiency of the equipment even in the idle state. They are load-independent losses. Their minimization therefore plays a very important role in long term grid connection and in transformers that operate in standby mode for long periods. Long-term operation with high no-load losses can lead to significant financial losses.
Short-circuit losses ( or winding losses) are due to the resistance of the transformer windings through which current flows. These losses are directly dependent on the load on the equipment – the higher the load, the higher the losses. Therefore, it is extremely important to design the transformer with a good quality conductor.

Minimise transformer losses: increase efficiency and reduce operating costs

There are various techniques and technological solutions aimed at reducing dead, short and no-load losses:

Optimization of core design: the core plays a significant role in the generation of idle losses. However, high quality materials (silicon steel) can reduce losses by reducing core losses and improving the overall efficiency of the device. It is also important to reduce eddy currents, which can be achieved by laminating the core. The core consists of thin sheets separated by an insulating layer.
Winding design optimization: losses due to conductor resistance can be reduced by using lower resistance materials. Optimisation of the winding geometry is also important. Proper winding layout can improve the efficiency of the transformer.
Use of modern technology: modern technology can also solve the problem of a transformer connected to the grid for a long time. There are materials with lower hysteresis and eddy losses and also modern control systems that optimize the load on the equipment in real time.

Transformer losses and their impact on operating costs and the environment

The presence of losses directly reduces the efficiency of the device. Losses in the iron (idle) reduce efficiency even at low load or even in standby mode. Losses in the windings (shorted) increase with load. Higher transformer efficiency means lower losses, and this translates into lower power consumption and more stable operation. Conversely, higher losses in the transformer increase power consumption. In addition, they can increase both cooling and maintenance costs. This is because losses are converted into heat that needs to be dissipated, and this requires an efficient cooling system. Prolonged exposure to higher losses can reduce service life, which in turn leads to more frequent repairs.

Energy losses in transformers also indirectly affect the environment. The amount of energy consumed has an impact on greenhouse gas emissions. The environmental burden is also increased by the more frequent disposal of transformers with shorter lifetimes due to high losses.

Investing in efficient transformers will bring significant long-term benefits

Although the initial cost of modern and low-loss transformers may be higher, ultimately minimizing losses leads to significant energy savings, reduced operating costs, and extended equipment life. Higher upfront costs are also recovered after just a few years in the form of lower utility bills and reduced operating expenses.

saving on electricity, transformer losses, minimizing losses

Minimising losses leads to long-term energy and cost savings. In continuous operation, energy savings can represent significant financial benefits. The benefits of quality transformers include fewer faults and downtime, which means lower repair and equipment replacement costs. More reliable operation with less risk of unexpected failures is just one of the significant benefits of extended lifetime.

Ak hľadáte efektívne a spoľahlivé riešenia, neváhajte kontaktovať spoločnosť BEZ TRANSFORMÁTORY. Pomôžeme vám vybrať najvhodnejšie zariadenie, pričom zohľadníme vaše špecifické potreby. Poskytneme vám aj komplexné poradenstvo v oblasti minimalizácie strát a optimalizácie energetickej účinnosti.

Transformer power: what it really means and why it matters

17. February 2025/0 Comments/in Blog/by Copy Digitalman

Transformers play a key role in the transmission and distribution of electricity. They allow the voltage to be stepped down and stepped up efficiently. Thus, they can minimise losses in the transmission of electricity over long distances. From the point of view of the stability of the entire power grid, the performance of the transformer is crucial. Improperly sized ones can not only lead to energy losses. What else is at risk can be found in the following lines.

Transformer power in units of kilovolt-ampere (kVA) or megavolt-ampere (MVA)

It expresses the amount of electrical energy that the device is capable of efficiently transferring between the input and output sides. BEZ TRANSFORMÁTORY manufactures oil-immersed equipment from 50 kVA up to a maximum output of 16 MVA and dry cast-insulated variants from 100 kVA up to a maximum of 10 MVA, with maximum equipment voltages up to 38.5 kV.

Factors affecting efficient operation

Too low a transformer output can lead to overloading, while equipment with unnecessarily high output is both inefficient and unnecessarily more costly.

Znížený výkon transformátora môže spôsobiť vyššie teploty, ktoré znižujú schopnosť zariadenia odvádzať teplo. Napríklad olejové modely majú vyššiu schopnosť odvádzať teplo než suché. Výber správneho typu chladenia tak priamo ovplyvňuje aj výkon a životnosť zariadenia.

short circuit in the power grid, transformer power — The quality of the supply voltage is very important for trouble-free operation. Fluctuations can cause higher losses and reduce efficiency.

The transformer achieves best efficiency at loads in the range of 50 to 70% of rated power

At low loads, it is unable to use its full capacity. On the other hand, overloading can cause overheating and an increase in heat loss.

The ratio between active and apparent power is determined by the power factor (cos φ). In optimum operation, it generally reaches the highest values, which means that the equipment is operating efficiently and maximising the delivery of useful energy.

Properly sized transformer power minimizes losses and contributes to even power distribution

When selecting the power, consider first of all the expected load on the network. Consider also that for installations in confined spaces, such as urban substations, higher power also means larger dimensions and more demanding space requirements.

large industrial transformer, transformer power

You need different transformer power for industrial plants and power stations and different power for public buildings, shopping malls and hospitals.

How to find the optimal solution? Recommendation when choosing a transformer

Vypočítajte si koeficient zaťaženia a zvoľte primeraný výkon. Zohľadnite aj priestorové možnosti, vlhkosť, teplotu a prašnosť prostredia. Zvážte, či ide o vonkajšiu, alebo vnútornú inštaláciu. Vonkajšie priestory umožňujú použitie väčších jednotiek. Olejové modely sú vhodnejšie pre vonkajšie aplikácie napríklad pre umiestnenie v trafostanici, zatiaľ čo suché typy sú prednostne určené do vnútorných prevádzok napríklad v priemysle.

BEZ TRANSFORMÁTORY is one of the leaders in the manufacturing industry and offers a broad portfolio of products designed for a variety of needs and applications. They provide long-lasting and efficient operation and represent a modern solution with an emphasis on safety and environmental friendliness. The company adapts to market needs, invests in research and development and develops products that meet the most stringent standards. It delivers optimal solutions and meets the needs of a variety of customers from small businesses to large industrial corporations.

Ak hľadáte spoľahlivé a efektívne riešenie, kontaktujte nás. Ponúkame široké portfólio olejových a suchých transformátorov, ktoré vám pomôžeme prispôsobiť presne vašim potrebám.

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