Transformers in photovoltaics: choosing the right transformer for maximum efficiency of a photovoltaic power plant

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Discussions of green energy often focus on photovoltaic panels, which convert sunlight into electricity, and inverters, which transform direct current into alternating current. While these components are crucial, there is another and often overlooked link in the chain between the PV array and our homes or industrial plants: the transformer. But transformers in PV are not limited to raising the voltage.

The role of transformers in photovoltaic power plants

Photovoltaic systems, whatever their size, have a fundamental challenge: the energy they generate must be adapted to meet the stringent requirements of the electricity grid.

Increasing tension

Photovoltaic panels produce direct current (DC), which the inverter then converts to alternating current (AC). However, this AC current is generated at a relatively low voltage. While this would be sufficient for normal domestic use, it is inefficient and uneconomical for transmission over medium and long distances to distribution points. Therefore, a transformer comes into play. It receives AC current from inverters and its main task is to radically increase the voltage to grid level (e.g. 22 kV, 35 kV, or up to 110 kV for large parks). Without this step, there would be huge energy losses. This is because higher voltages allow power to be transmitted at a much lower amperage, thus minimising losses in the lines.

Insulation and system safety

The transformer also performs a safety function. It provides galvanic isolation of the photovoltaic system from the distribution network. This decoupling protects the expensive and sensitive inverters from surges, surges and faults that can occur on the grid, while ensuring that faults in the solar park do not critically affect the stability of the utility grid.

transformer in photovoltaics

Typology of transformers in photovoltaic systems

BEZ TRANSFORMÁTORY offers two main types of transformers for photovoltaic parks: oil-immersed and dry-type transformers.

Oil Transformers for Renewable Energy

Oil-cooled transformers are cooled by mineral oil and are the most widely used type in the long term, particularly suitable for outdoor PV park environments where they can withstand adverse weather conditions. Thanks to oil cooling, they can dissipate heat efficiently even under higher loads and offer excellent reliability and extended service life.

oil transformer

Dry-type transformers for renewable energies

Dry-type transformers do not use liquid dielectric, but are cooled by air. They are ideal for indoor and container stations where there are increased demands on fire safety, for example in close proximity to inverters or in densely built-up areas. They are more environmentally friendly, require less maintenance and eliminate the risk of oil leaks.

dry transformer

Impact of transformers on the efficiency and stability of power transmission

The quality of the transformer directly determines the economic success and technical reliability of the entire solar project.

Efficiency and loss minimisation

As we have already mentioned, loss minimisation is a key factor. This is because by increasing the voltage, the current drops, which dramatically reduces the heat loss. Transformers with low intrinsic losses maximize the amount of energy produced that actually reaches the consumer. Thanks to their robust design and life expectancy in excess of 30 years, transformers guarantee a long-term return on investment and reliable operation of the PV park in a variety of climatic and operating conditions. The investment in a transformer with low no-load and short-circuit losses will thus pay for itself many times over during the long lifetime of the project.

Network stability and quality control

Photovoltaics, although a clean source, can present challenges in the form of voltage fluctuations and THD harmonic distortion generated by inverters. Therefore, advanced transformers have systems that allow smooth and automatic voltage regulation, thus maintaining grid stability even with rapid changes in sunshine. In addition, the transformer helps to dampen and filter harmonic currents. This ensures that the energy supplied to the distribution system is clean and meets all standards.

transformer in photovoltaic power plant

The challenge of the future

As PV expands and integrates into smart grids and battery storage, the demands on transformers will only increase. Their quality design, ability to handle fluctuating loads and minimize losses are essential for a successful and sustainable transition to green energy.

If you are currently designing or optimizing your PV park and are looking for a customized solution that guarantees low losses and long lifetime, contact us. Our technical specialists will be happy to help you with your selection.

Transformer life: how to extend its operation?

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Technical, operational and environmental factors determine how long a plant will operate reliably. Deteriorated insulation, overloading or inadequate maintenance can lead to reduced performance, higher losses and ultimately premature failure. Thus, reduced transformer lifetime is not just a technical problem. It also represents a significant financial loss, as the replacement or overhaul of equipment is one of the most costly interventions in the electricity industry.

Factors affecting transformer life

Transformer life is the result of the interplay of a number of physical, chemical and operational phenomena. The following factors are among the most significant.

Thermal stress and overload

If the equipment is operated at a higher temperature than specified by the manufacturer for an extended period of time, the degradation of insulation materials is accelerated. Therefore, make sure that the transformer is properly sized and avoid overloading it for long periods of time. Even short-term overloading can leave lasting effects if repeated too often.

Quality of the insulation system

If the condition of the insulation system deteriorates, not only the electrical strength but also the overall service life of the transformer is reduced. The most common problems are moisture, oil oxidation and contamination by dirt. For this reason, regularly check the physicochemical properties of the insulating oil. Prevention in this case is much cheaper than subsequent repair.

Vibration and mechanical stress

Prolonged vibration can lead to loosening of windings, damage to connections and weakening of the core. Proper design is therefore the basis for a long service life. In practice, it is recommended to check the fit of the screws and damping elements regularly, especially after major short circuits or equipment transports.

Influence of the external environment

Dust, moisture, corrosive environments or extreme temperatures can accelerate the ageing of materials and reduce insulation properties. In addition, transformers located outdoors are exposed to sudden changes in temperature, UV radiation and weathering. Therefore, use appropriate protective coatings, seals and filtration systems. Proper ventilation and regular leakage checks are also important, especially for oil-immersed transformers.

Quality of installation and pre-commissioning checks

Improper cable connections, loose contacts or neglected cooling can significantly shorten the operating life of the transformer. The key is therefore professional installation, careful checking before start-up and adherence to the manufacturer’s recommendations throughout the lifetime of the transformer.

Factors Affecting Transformer Lifetime, Quality of Installation and Inspection Before Starting

Inspections and revisions as the key to long transformer life

Even the best quality transformer needs regular checks and inspections. A properly set up inspection program can extend the life of a transformer by decades while increasing its efficiency by reducing energy losses and minimizing the risk of failure. Inspections and revisions should include the following steps:

  • oil tightness check,
  • analysis of oils and gases,
  • electrical testing, protection calibration and transformer earthing,
  • control of noise, vibration and ambient temperature,
  • correct setting and securing of the tap changer.

The investment in inspections and revisions always pays off in lower operating costs, higher transformer efficiency and, above all, a longer and more reliable service life.

Preventive measures to reduce wear

Although the transformer has its design limits, the right approach can significantly extend its life and maintain high efficiency throughout operation. Preventive measures do not only mean regular inspections, but also strategic decisions on operating methods, upgrades and operator behaviour:

  • proper operation and load management,
  • modernisation and technical improvements,
  • temperature and humidity control,
  • operator training and competence,
  • strategic planning and predictive maintenance.

Preventive measures are not just a set of technical steps, but an overall philosophy of how to approach a facility. If applied consistently, they can extend the life of a transformer by decades while reducing both energy and service costs.

Transformer voltage transformer: key role and practical application

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Without transformers, electricity could not travel efficiently and safely from the power station to your socket, nor would most industrial machinery work. But all functionality depends on one key principle. It is voltage conversion.

How transformers change voltage level

A transformer is essentially a static device that transfers electrical energy from one circuit to another without direct electrical contact, using a magnetic field. The principle of electromagnetic induction is the basis for voltage transfer in a transformer , discovered by Michael Faraday. When an alternating current passes through the primary winding, it creates a constantly changing magnetic field in the core. This changing field passes through the secondary winding and induces a voltage in it. What the output voltage level will be depends entirely on the ratio of the number of turns of the primary and secondary windings. This relationship defines the key parameter of the transformer: the transformation ratio.

Voltage units and conversion of voltage units

When discussing voltage conversion, we cannot avoid the fundamental physical quantity: electrical voltage. The basic unit of electrical voltage in a system is the volt, named after the Italian physicist Alessandro Volta. The conversion or transformation of voltage units is, of course, necessary for the precise design and operation of networks. When we need to determine what voltage a transformer will handle, we always work in consistent units: volts, millivolts, kilovolts or megavolts.

step-up and distribution transformers

From mains to USB charger

The role of transformers is divided into two main categories: strategic (in the power sector) and local (in industry and households). At BEZ TRANSFORMÁTORY, we specialize in distribution transformers, which are critical in the transition between the grid and the end consumer.

The key reason for voltage transfer is to minimize transmission losses. The higher the voltage, the lower the current, and the lower the heat losses on the lines. Boosting transformers operate in the vicinity of power plants . Electricity is generated at lower voltages (e.g. 10-25 kV). Step-up transformers immediately convert it to very high transmission voltages (e.g. 110 kV, 220 kV, 400 kV) for efficient long-distance transmission. As the power approaches populated areas, distribution transformers step in . These carry out a gradual step-down.

In the industrial environment, voltage conversion is important for powering specific machines and improving safety. Finally, also in solar parks and wind turbines, transformers raise the generated voltage to grid level so that it can be distributed efficiently.

Transformers are part of your life all the time. For example, you will find a distribution transformer in front of your house that reduces the voltage from 22 kV to the standard 230 V for your home. Most of the home voltage transfer is then provided by small adaptors (which contain miniature transformers or electronic switching power supplies). Almost every device that does not run directly on 230 V (mobile phone chargers, laptop chargers, LED lighting) needs a step-down transformer or electronic substitute to safely reduce the voltage (e.g. from 230 V to 5 V for USB or 12 V for lighting).

Voltage transfer is more than just a technical operation

It is the pillar on which modern electricity infrastructure stands. It allows us to transmit electricity with minimal losses while delivering it safely to every device, from a huge production line to the smallest LED bulb.

voltage transfer by transformer

As the only manufacturer of distribution transformers in Slovakia with more than 120 years of tradition, BEZ TRANSFORMÁTORY ensures that this critical voltage transfer takes place reliably and efficiently throughout the distribution network, making it a key link in the stability of the energy infrastructure.

How to calculate transformer parameters

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Do you know how to calculate the transformer needed? Correct calculation is the basis for reliable operation, long life and high efficiency. In order for it to work optimally, you need to know exactly its transformation ratio, power, efficiency and losses. However, it is important to understand the basic relationships behind the calculations themselves, whether it is to determine the number of turns, the winding voltage or the power parameters. We therefore bring you a practical step-by-step guide explaining how to calculate a transformer and how to calculate the basic transformer parameters, from transformation ratio to efficiency and losses.

Basic concepts before transformer calculation

Before getting into the actual calculation of the transformer, it is important to understand a few basic concepts and relationships that determine its behavior.

Primary and secondary winding voltage

The transformer has two main parts. A primary winding, to which the input voltage U1 is connected, and a secondary winding, from which the output voltage U2 is taken. The ratio between these two voltages determines the so-called transformation ratio (conversion), which is a basic parameter of every transformer:

  • If U1>U2, it is a step-down (voltage) transformer.
  • If U1<U2 , we are talking about a step-up transformer.

Transformer current and power

The current in the primary winding is denoted by I1 and in the secondary winding by I2. For an ideal transformer, the power at the input and output is the same. However, in a real transformer, some of the power is lost due to thermal and magnetic losses, so the output power is always slightly less than the input power.

Transformer efficiency

Efficiency (η) expresses how efficiently the transformer converts energy. It is defined as the ratio of output to input power: η =Pout/Pin× 100 %. High quality transformers, such as those manufactured by BEZ TRANSFORMÁTORY, achieve efficiencies of 98-99%, reducing operating costs and thermal loads.

Transformer losses

The losses can be divided into two main groups:

  • Stray losses (in iron) occur in the transformer core due to magnetic phenomena (hysteretic and eddy currents).
  • Short-circuit losses (in the windings) are due to the resistance of the windings, in which some of the energy is converted to heat.

Accurate calculation of transformer losses is important to determine its efficiency, cooling capacity and economic operation.

Types of transformers by application

Before the actual calculation, it is also necessary to know the purpose of the transformer, because the method of calculation depends on it:

  • Single-phase transformers are common in smaller equipment and power supplies.
  • Three-phase transformers are used in power and industrial applications.
  • Measuring transformers are designed for accurate current or voltage measurements.
  • Power transformers transmit high power in electrical networks.

These concepts form the basis without which the transformer calculation would not be accurate or understandable.

transformer calculation

Calculation of the transformation ratio

One of the basic parameters that determine the behavior of the transformer is the transformation ratio. This ratio indicates how many times the voltage between the primary and secondary windings changes.

The transformation ratio (k) is determined by the formula: k = U1/U2 =N1/N2,where:

  • U1= primary winding voltage (V)
  • U2= voltage on the secondary winding (V)
  • N1= number of turns of the primary winding
  • N2= number of turns of the secondary winding

This relationship shows that the ratio of stresses is the same as the ratio of the number of turns. So, for example, if we want to reduce the voltage by a factor of ten, the secondary winding must have ten times fewer turns than the primary.

Application of transformation ratio calculation in practice

Calculating the ratio helps determine the number of turns of the windings and the cross section of the core. By verifying the transformation ratio, it can be determined whether the device is in order or has a damaged winding. Modern software and online calculators make it possible to quickly determine the correct transformation ratio without manual calculations.

Almost all transformers also have a tap changer that allows you to vary the voltage on the primary side, normally between -5% and +5%. By changing the tap, you can keep the secondary voltage constant. Such regulation can be in an off load or on load state. Transformers with an OLTC on-load tap changer are installed at locations with frequent voltage changes on the primary side. The demand for these transformers is increasing due to the renewable resources connected to the distribution grids.

transformer calculation

Recommendation of the experts from BEZ TRANSFORMÁTORY

When designing or checking the transformer, always compare the calculated transformation ratio with the nominal data on the label. Deviations may indicate wear or a fault in the winding.

Calculation of transformer power

The transformer power rating determines how much electricity the device can transfer from the primary circuit to the secondary circuit without excessive heating or losses. This parameter is critical in both the design and selection of a suitable transformer for a particular application.

The basic relationship for the apparent power of a transformer is S = U × I, where:

  • S = apparent power (VA or kVA)
  • U = voltage (V)
  • I = current (A)

This formula expresses the output of one phase. For a three-phase transformer, the power is calculated as follows.

The result is most often given in kilovolt-amperes (kVA), which represents the rated power of the transformer.

How to determine the required transformer power

When designing or selecting a transformer, it is necessary to take into account:

  • the sum of the outputs of all connected devices,
  • power reserve: it is recommended to increase the rated power by 10-20%,
  • nature of the load: continuous, intermittent or impact,
  • power factor and operating conditions ( e.g. ambient temperature, cooling).

When deciding on power, evaluate efficiency, as transformers reach their highest efficiency at loads between 40-60% of rated power.

Properly selected power ensures stable operation and minimizes thermal stress on the windings. Transformer power is a key parameter that affects its size, weight and operating efficiency. Therefore , it is important to perform an accurate calculation of the transformer at the design stage and verify it by practical measurement or software simulation.

When is transformer replacement needed?

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Every piece of equipment has a lifespan, and after years of operation there comes a point when repairs are no longer enough. Replacing the transformer will prevent sudden breakdowns, power outages or unnecessary costs for constant maintenance. In this article, you’ll learn when it’s time for replacement, what signs indicate wear and tear, what criteria to consider when making a decision, and how the process of installing a new transformer works.

Transformer wear symptoms

Early recognition of warning signals will prevent crashes and costly outages. The most common signs include:

  • increased overheating and unusual noise,
  • transformer power drop,
  • damage to the insulating oil,
  • insufficient insulation or leaks,
  • mechanical damage and corrosion,
  • increase in breakdowns and more frequent maintenance.

If the transformer exhibits excessive heating or makes unusual noises, it may indicate damage to the windings, core or insulation materials. A gradual increase in voltage drop, reduced efficiency or fluctuations in output parameters indicate that the transformer can no longer perform its original function. Oil discolouration, the presence of moisture, odour or visible oil leaks indicate that the insulation system is losing its properties. Cracks, rust, damaged terminals or loose connections on the bushings or transformer housing are not only aesthetic, but especially a serious safety problem.

If the transformer requires regular repairs or faults recur at short intervals, this is a clear sign of approaching end-of-life. In such cases, transformer replacement is often a more economical solution than further investment in repairs.

transformer replacement

Transformer replacement criteria

Recognising the signs of wear and tear is only the first step. After that, the actual decision as to whether transformer replacement is necessary depends on a number of factors:

  • the age and service life of the equipment,
  • economic efficiency,
  • change in performance requirements,
  • norms and safety standards,
  • Preventive exchange for critical infrastructure.

Transformers have a limited design life, which is most often in the range of 20-40 years, depending on the type and operating conditions. If the cost of regular repairs and maintenance exceeds the cost of a new unit in the long term, replacement is the logical choice. When the grid is expanded, demand increases or technological changes occur, the existing transformer may not be sufficient. Therefore, installing a new unit with a higher capacity will ensure reliable coverage of future needs. In energy-intensive operations or facilities where an uninterrupted supply of electricity is crucial (hospitals, data centres, industrial plants), it is often more advantageous to replace the transformer as a precautionary measure than to risk an unplanned outage.

Newer standards require stricter legislative requirements and environmental regulations. Conversely, older types of transformers may contain insulating oils or materials that no longer meet current environmental and safety standards.

An old transformer manufactured according to the standards in force at the time has, among other things, higher operating costs. Although the transformer is less loaded, it still draws some energy (no-load losses) to magnetize the core. The cost of such a transformer represents a significant financial cost. In addition, older standards set these losses at much higher levels than the stringent European Union standards in force today, which instruct manufacturers to comply with the Ecodesign 2 loss level on all newly installed transformers (some exceptions apply). Transformer loss capitalisation is used to calculate transformer payback. Simply put, it is the conversion of technical values (losses) into financial costs.

The process of installing new equipment

Transformer replacement itself is not just about dismantling the old equipment and installing the new one. In fact, it is a complex process that requires thorough preparation, expert supervision and precise execution of every step:

  1. Needs analysis and solution design
  2. Transformer selection and manufacturing
  3. Dismantling old equipment
  4. Installation and testing of the new transformer
  5. Warranty and post-warranty service

The first step is to assess the current and expected electricity consumption. Modern transformer manufacturing allows the equipment to be tailored to the customer’s specific requirements, from capacity and cooling system to environmentally friendly insulating oil solutions. Once the needs have been assessed, the old transformer is professionally disconnected from the grid and safely dismantled by experts. This step also includes environmentally friendly disposal or recycling, that meets applicable environmental standards. Delivery of the new equipment is followed by installation, connection to the network and carrying out the necessary tests. Testing includes checking electrical parameters, insulation strength and the functionality of protection systems. After commissioning , regular maintenance and monitoring of operating parameters is important . Professional servicing prolongs the life of the equipment and reduces the risk of unexpected failures.

professional transformer service

If your transformer is nearing the end of its useful life or exhibiting any of the above symptoms, don’t hesitate to contact the professionals. At BEZ TRANSFORMÁTORY, we provide a full range of services from needs analysis to custom transformer fabrication to installation and long-term service. We can also provide you with a loss capitalization calculation and therefore when you will recover the cost of a new transformer.

Battery storage: the future of energy

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Battery storage is becoming a key element of modern energy networks. They can stabilise the grid, provide back-up power and optimise power flow. They also represent a technical challenge for transformer and power distribution companies. But it is also an opportunity to integrate modern solutions into existing infrastructure. Choosing the right type of storage, its capacity and compatibility with transformers are critical factors for the efficient and reliable operation of any power system.

The importance of battery storage in modern energy networks

Modern electricity grids increasingly have to cope with fluctuations in power generation, especially as a result of the growing share of renewables. Battery storage makes it possible to smooth out such fluctuations and provides flexibility and a reliable supply of electricity. The main benefits of battery storage include:

  • network stabilization,
  • support for renewable sources
  • and backup power supply.

However, battery storage integration is not just a question of battery capacity, but also of proper coordination with transformers and other grid infrastructure. Only a well-designed system can optimize power flow, extend equipment life and reduce operating costs.

battery storage and renewables


Overview of battery storage technologies

There are a number of battery storage technologies that vary in capacity, durability, efficiency and cost:

  • Lithium-ion batteries are the most widely used technology in modern storage. They are used in systems where fast and efficient energy regulation is required.
  • Lead acid batteries are a traditional technology with lower costs. They are suitable for backup systems or smaller applications where high cycle frequency is not critical.
  • Alternative technologies include sodium, vanadium and other battery types that may be more economically viable at large capacities.

Battery storage integration with transformers

Transformers play an important role in the distribution of electricity and its interconnection with storage, allowing power flow to be optimised and losses minimised. Efficient integration of battery storage with transformers is therefore crucial for reliable and energy-efficient grid operation.

  • Battery storage needs to be sized to work with the capacity and voltage levels of the transformers.
  • Modern systems allow intelligent control of the energy supply between the battery, transformer and grid according to actual demand and production.
  • Properly designed interconnection protects transformers and batteries from overloads, voltage fluctuations and other faults.

The integration of battery storage represents a strategic step towards the modernisation of the energy infrastructure and provides transformer companies with a competitive advantage in implementing smart and flexible solutions.

battery storage

Economic aspects, price and interconnection with transformers

When implementing battery storage, consider not only the battery technology, but also the type of transformers the storage will work with. The cost and efficiency of the overall system will then depend on the combination of these elements.

  • Lithium-ion batteries provide high energy density and long life, making them ideal for working with dry-type transformers used in areas with high safety requirements.
  • Larger battery storage is better combined with oil transformers that can handle higher loads and energy peaks.
  • In industrial applications or critical equipment , special transformers are used which , together with battery storage, allow the power flow to be optimised and outages to be minimised.

Battery storage is an integral part of the modern energy sector, especially in an era of increasing renewable energy sources. The choice of the type of battery storage and its integration with dry oil or special transformers affects efficiency, reliability and return on investment.

Transformation ratio: how it works and why it is important

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In order for a transformer to effectively change the voltage between different parts of the network in electricity transmission and distribution systems, it must have a well-defined transformation ratio (also called transformer conversion). This is a fundamental parameter of any transformer. It determines how the voltage changes between its input and output, i.e. between the primary and secondary windings.

Transformation ratio

The transformation ratio represents the ratio between the number of turns on the primary coil and the number of turns on the secondary coil of the transformer. It determines how the electrical voltage changes as it passes through the transformer. It is denoted by the letter k . In practice, it is often also referred to as the ratio of input to output voltage.

Two basic types of transformers according to transformation ratio

The transformation ratio is a basic indicator of how a transformer adapts its electrical parameters to the requirements of a particular device or network:

  • Step-down transformer (k > 1): it is used to reduce the voltage. An example is an adapter that converts 230 V to 12 V for household appliances.
  • Step-up transformer (k < 1): used to increase the voltage, for example when transferring electricity from sources to grids.
installation of modern transformer

For decades, BEZ TRANSFORMÁTORY has been manufacturing quality transformers that accurately reflect the requirements for the correct transformation ratio from distribution networks to industrial applications.

See our current offer or contact us for a customized transformer design.

How is the transformation ratio calculated?

The calculation of the transformation ratio is simple. As we have already indicated, the transformation ratio is expressed either by the number of turns on the windings or by the voltages. The two expressions are mathematically equivalent: k = U₁ / U₂ = N₁ / N₂, where:

  • k = transformation ratio
  • U1, U2= voltages on primary and secondary windings
  • N1, N2= number of turns on primary and secondary windings
transformation concept, scheme

Transformation ratio and its importance in practice

The correct setting of the transformation ratio has a major impact on the operation of electrical equipment and entire distribution networks:

  • Efficient power transmission: in long-distance power transmission, voltage boosting is used with the help of transformers with a low transformation ratio. This makes it possible to reduce the current and thus the line losses. For distribution to households, the voltage is again reduced using step-down transformers.
  • Voltage adaptation for different equipment:With the right transformation ratio, we can adapt the output voltage of electrical equipment so that it operates safely and reliably.
  • Measurement and protection systems:Current and voltage transformers enable high voltage currents to be monitored safely by transforming them into smaller measurable values using a precisely defined transformation ratio.
  • Industrial and special applications: Special transformers with atypical transformation ratios are often used in industry . They allow specific voltage levels for machines, lines or laboratory instruments. This is because without the correct transformation ratio setting, these devices would not be able to function.
transformer failure

The transformation ratio is therefore a key parameter of any transformer and determines how the voltage between the input and output of the device changes. Its correct understanding and calculation are essential in the design, set-up and safe operation of electrical systems.

If you are looking for a reliable partner for the design and manufacture of customized transformers, take a look at the offer of BEZ TRANSFORMÁTORY, a leader in power solutions.

How the transformer works: a simple explanation for everyone

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Even if you don’t know how a transformer works, it would be hard to imagine your life without one. Yet many people don’t know what it is and how it actually works. That’s why today we’ll explain the principle of its operation in a simple and understandable way. We will look at the basic processes that take place in it and show you its practical use.

The principle of operation of the transformer

The transformer changes the electrical voltage. It can either increase or decrease it. Its basic parts include coils of aluminum or copper wire, called primary and secondary windings. Between them is a metal core, usually made of mild steel.

When an alternating electric current is applied to the first coil (primary winding), a magnetic field is created around it. This magnetic field travels through the metal core of the transformer to the second coil (secondary winding) where the changing magnetic field “touches” the conductor and causes a new electric current to appear in it. This is called induction. Depending on how many turns the second coil has compared to the first, the voltage will either increase or decrease.

This phenomenon is described by Faraday’s law of electromagnetic induction, which states that “a change in the magnetic field over time induces an electric voltage in the coil”. This means that the transformer only works with alternating current because direct current would not create the changing magnetic field needed for induction.

This way the transformer changes voltage without anything moving in it. The whole process is based on a magnetic field and alternating current.

transformer

How the transformer and its individual parts work

The transformer has two main windings. The primary winding is the part that receives the electric current from a source such as a power plant. The secondary winding passes the treated voltage to where we need to get it, for example to household appliances. The two windings are wound from copper or aluminium wires and separated from each other so that the electric current cannot flow directly, but only through the magnetic field in the core.

The core is a metal part, most often made of steel or iron, which is placed between the windings. Its function is to conduct the magnetic field generated in the primary winding to the secondary winding. Thanks to the core, the magnetic field is concentrated and the transformer operates efficiently.

Types of transformers

In practice, we encounter various types of transformers, which differ in design and application:

  • Dry transformers have an air-cooled core and windings. They are mainly used indoors or where cleanliness and safety are important, such as in hospitals or offices. They are more environmentally friendly as they do not contain oil, but have lower maximum outputs.
  • Oil Transformers are filled with insulating oil, which helps to cool the windings and insulate them at the same time. They are mainly used in large substations and high power applications as the oil improves heat dissipation and reduces the risk of overheating.
  • There are also special transformersthat are designed for specific purposes, for example, interconnecting, three-winding, inverter, single-phase, excitation or earthing transformers.
  • Many are also adapted to work with solar panels, wind turbines or other sources. Transformers for renewable energy sources supply electricity with specific parameters and help to connect these sources to the grid correctly.
transformer

Practical use of transformers in electrical networks

Transformers safely and efficiently transmit electricity from power stations to our homes. This is because electricity is generated in large, high-voltage power stations to minimise losses in long-distance transmission. However, when it comes closer to where we want to use it, substations have to reduce its voltage to a level that is safe for homes or industry. This allows us to plug in appliances such as a TV, computer or fridge at home without worrying about anything going wrong.

BEZ TRANSFORMÁTORY, we could not…

… use common household appliances, as most of them need low voltage.

… to transmit electricity over long distances without huge losses.

… to work safely with high voltage in industry or power industry.

Understanding the basic principle of how a transformer works helps us to better understand how important these devices are in our daily lives. Even if we don’t see them, modern society could not function without them.

Transformer design: from concept to implementation

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At BEZ TRANSFORMÁTORY, we focus on developing and manufacturing transformers that meet high demands not only for performance and reliability, but also for energy efficiency, safety and long-term sustainability. A well-designed prototype is always the result of a complex process. The design of transformers is therefore by no means random. It combines computational precision, knowledge of materials and practical experience from real operation.

Basic design principles of transformers

It is a multi-stage process in which technical parameters are linked to the practical requirements of a particular operation. Each stage, of course, has its own significance.

  • The first step is the precise specification of technical and operational parameters. The aim is to specify the exact requirements that the transformer must meet. Specifically, its power, input and output voltages, rated frequency, type of operation, installation conditions, cooling requirements and other client specifications.
  • The shape and material of the core has a major influence on the dimensions, weight and efficiency of the device . The choice of material and sheet thickness also affects core losses. Thus, the correct choice of core ensures not only high plant efficiency but also mechanical stability, good cooling and lower noise.
  • The transformer windings are designed with emphasis on current load, heat loss and electrical strength. The design of transformers varies by number of turns, conductor cross-section, conductor material, winding geometry and insulation type.
  • The stability of the device during operation, but also during transport, is ensured by the mechanical part of the design. This includes the assembly concept, the dimensioning of the structural elements, protection against vibrations and shocks, as well as compliance with the insulation properties.
  • Each proposal will undergo a thorough loss analysis. Losses affect not only efficiency but also operating costs.

The goal of design optimization is to find a balance between size, performance, efficiency and production cost.

transformer design optimization

Dimensions, shape and power characteristics of transformers

They result from the specific technical requirements and the environment for which the transformer is intended. These factors also fundamentally influence the choice of construction materials, the loss rate and the cooling method.

  • The basic parameter is the rated power of the transformer. As the power increases, the dimensions of the core and the cross section of the windings also increase. Higher power means higher currents, which in turn require more robust conductors, better cooling and reinforcement of the insulation system.
  • The frequency of the power system has a significant impact on the core design . In conventional power applications, transformers are designed for a standard frequency of 50 Hz. Higher frequencies are used with smaller cores, resulting in reduced weight and size. Lower frequency, on the other hand, requires an increase in core cross section, making the transformer larger and more expensive.
  • The choice of cooling has a direct influence on the winding layout, the construction material used, but also the overall volume of the device.
  • Practical constraints must also be taken into account in the design. The availability of materials, the production technology used or the method of transport also influence the production possibilities and the final price of the equipment.

It is also important to comply with weight limits for handling and transport during manufacture, which is also part of the design of transformers.

transformer design and its effect on transformer transportation

Transformer design testing

In the company BEZ TRANSFORMÁTORY we emphasize systematic inspection from common series transformers to specifically designed units. Once the design process is complete and a prototype is constructed, we thoroughly test the equipment. The aim is to verify that it meets all technical parameters and standards, that it behaves stably in real-life conditions and that the design matches the assumptions of the calculation model.

Prototype testing is crucial not only for safety but also for confirming the optimization of the design. It can reduce potential manufacturing deviations, improve the design for series production and ensure long-term reliability.

Production, documentation and final inspection

After successful validation of the design and testing of the prototype, the production phase follows. Based on the final design, complete production documentation is prepared. For projects with specific requirements, an individual production plan is also drawn up. Once production is complete, final assembly of the transformer follows. Each transformer then undergoes a final output test in which all electrical and mechanical parameters are verified. Only after successful completion is the equipment ready to be handed over to the customer.

How to ensure the highest efficiency of the transformer

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Today, every kilowatt hour is important. Transformer efficiency therefore plays a key role not only in terms of cost savings, but also in the context of sustainability and environmental responsibility. Even small inefficiencies in operation can translate into a significant loss of energy and money in the long run. In addition, there are now increasingly stringent demands on manufacturers and operators. So the question is how to ensure the highest transformer efficiency?

What does transformer efficiency mean?

When we talk about the efficiency of a transformer, we mean the ratio between the electrical power entering it and the power leaving it. In other words, it is about how much power passes through the transformer without losses. The ideal would be 100%, of course, but in practice transformers always experience some losses. For small transformers this may be a negligible amount of energy, but for large units in industrial plants or distribution networks it is a significant factor.

Why is efficiency never 100%?

Because the laws of physics apply inexorably. For every time energy is transferred, some of it is converted into heat or some other form that cannot be used. Ideally, the efficiency of a transformer should be in the range of 98 to 99.7 %, depending on the type, power and operating conditions. Modern transformers are therefore designed to minimise losses.

Factors influencing efficiency

For a transformer to work as efficiently as possible, it is not enough to have a good design. The materials used, manufacturing technology and correct operation also play an important role.

  • The heart of the whole device is the transformer core. The losses that occur in it can be significantly influenced by choosing the right material.
  • Another source of loss is the windings, i.e. the coils through which the electric current flows. Here the material, shape and arrangement of the windings and the cross-section of the conductor play a role.
  • The losses in the transformer are largely converted to heat. If it is not dissipated properly, it increases the temperature of the components, leads to reduced efficiency and faster aging of insulating materials. The transformer cooling system can be optimized by varying the type of finning, oil flow or fan placement.
  • The transformer should exactly match the planned operation. An oversized one may have unnecessarily high iron losses at low load. Conversely, an undersized one will suffer from increased heating and faster wear.
reliable transformer

The right combination of these factors can determine whether a transformer will be a reliable helper or a source of unexpected expenses.

Proper operation and maintenance

Even the best designed and manufactured transformer can lose efficiency if not operated properly. Long-term efficiency is the result not only of quality design, but also of responsible operation.

  • The transformer requires regular technical care. Basic activities include checking the insulating oil, measuring the temperature and load, removing dust and dirt, and checking the mechanical connections and insulation. Properly performed maintenance can extend the life of the equipment by years.
  • The transformer should be operated in the range for which it was designed. Continuous overloading leads to temperature rise, increased losses and faster aging of materials. However, prolonged significant low loads cause unnecessary iron losses and inefficient operation.
  • The efficiency of the transformer also decreases due to hidden faults or substandard conditions. Excessive moisture in the oil or windings, weak contacts or corroded connections, vibration and noise, or contamination around cooling parts can be problems. However, preventive diagnostics and early intervention are cheaper and more effective than dealing with the consequences.
transformer efficiency

At BEZ transformátory, we believe that service and support after delivery are just as important as the production itself. We are a reliable partner who can help you not only with the selection of equipment, but also with its efficient operation throughout its lifetime.

Highest efficiency is not an accident, but the result of the right decisions

Losses in the core and in the winding have the greatest effect on efficiency. However, they can be significantly reduced by quality design and materials. Cooling, proper sizing and manufacturing technology have a major impact on energy losses. Efficient operation and regular maintenance are essential for long-term reliability and high efficiency. However, an investment in a high quality, high efficiency transformer pays for itself in lower operating costs over its lifetime.

V BEZ TRANSFORMÁTORY we combine more than 100 years of experience with the latest technology and an individual approach. The result is transformers that meet the most stringent standards, fulfil their purpose efficiently and operate reliably and for the long term.

Interested in the highest possible efficiency transformer for your project? We will be happy to advise you, contact us.

We are the only manufacturer of distribution transformers in Slovakia with more than 120 years of experience and a design life of 30 years.

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