Transformers direct from the manufacturer

Transformers, also known as transformers or voltage converters, are electrical devices that ensure that alternating voltages or alternating currents are converted from one voltage level to another. A transformer works by electromagnetic induction and plays a central role in the power supply.

1. Voltage conversion
   • Transformers convert high voltages used for the transportation of electrical energy into lower voltages that are safe for use in homes and businesses. This makes them indispensable for the power grid.
2. Insulation
   • Transformers also serve to insulate electrical systems, which increases safety. They prevent faults or errors from spreading from one part of the system to other parts.
3. Power distribution
   • Voltage transformers enable the efficient distribution of electrical energy over long distances by minimizing energy losses. Without transformers, a reliable power supply would not be possible.
4. Signal transmission
   • In communication technology, transformers are used to adjust signal levels and decouple signal paths.

The transformer, often also referred to as a transformer, current transformer or power transformer, is crucial for ensuring that electrical energy can be used safely and efficiently.

A transformer consists of several basic components that work together to enable the conversion of electrical energy from one voltage level to another. Here is a simple explanation of how the components of a transformer work together and how it functions.

1. Primary winding
   • The primary winding is a coil of wire that is connected to the input AC voltage. When alternating current flows through the primary winding, it creates a changing magnetic field.
2. Core
   • The core is usually made of ferromagnetic material (such as iron) that concentrates and conducts the magnetic flux lines. The core amplifies the magnetic field generated by the primary winding and ensures that the magnetic field is efficiently transmitted to the secondary windings.
3. Secondary winding
   • The secondary winding is another coil of wire that receives the magnetic field conducted by the core. The electromagnetic induction generates a voltage in the secondary winding that depends on the original voltage level. Depending on how many turns the secondary winding has in comparison to the primary winding, the voltage can be increased (step-up transformer) or decreased (step-down transformer).
4. How it works
   • Magnetic coupling: When the primary winding is supplied with alternating current, it generates a changing magnetic field. This magnetic field is passed through the core and reaches the secondary winding.
   • Induction: The changing magnetic field generates a voltage in the secondary winding. This voltage is proportional to the number of turns in the secondary winding and the primary winding. If the secondary winding has more turns than the primary winding, the output voltage will be higher (step-up). If it has fewer turns, the voltage will be lower (step-down).
   • Energy transfer: The electrical energy is transferred from the primary side to the secondary side without there being a direct electrical connection between the two sides. This enables the voltage to be converted and at the same time ensures insulation between the two circuits.
5. Cooperation between the components
   • The primary winding generates the magnetic field.
   • The core conducts this magnetic field to the secondary winding.
   • The secondary winding converts the magnetic field back into electrical energy, but with a different voltage depending on the number of windings.

This cooperation between the components enables a transformer to convert AC voltages efficiently, making it an indispensable component in power grids and electronic devices.

There are different types of transformers that are used depending on the application and requirements. Here are some of the most common types of transformers:

1. Power transformers
   • These transformers are used in power transmission and distribution systems to reduce the voltage of high-voltage lines to the low voltage suitable for consumption. They are used in power stations, substations and at various points in the electricity grid.
2. Distribution transformers
   • These transformers are used to reduce the voltage of power lines to a level suitable for consumption in buildings or industrial plants. They are used in distribution systems to supply electricity to homes, offices and industrial plants.
3. Switching transformers
   • These transformers are used in electronic circuits to increase or decrease the voltage. They are used in devices such as computers, televisions, audio amplifiers and other electronic devices.
4. Isolating transformers
   • These transformers are used to isolate the energy transfer between two electrical systems and change the voltage at the same time. They are used in industrial, isolation and safety applications.
5. Autotransformers
   • These transformers have a single winding that serves as both the primary and secondary winding. They are used to increase or decrease voltages and are used in devices such as voltage regulators, lamps and electric motors.
6. Choke transformers
   • These transformers are used to limit and control the flow of current in circuits. They are used in electronic circuits, especially in inverters, rectifiers and frequency converters.

These are just a few examples of different types of transformers and their applications. However, there are many other specialized transformers for specific applications such as measurement and instrument transformers, impulse transformers, high voltage transformers, etc.

Transformers are usually manufactured in several steps. Here is a general description of the manufacturing process:

1. Winding the coils
   • First, the copper wires are wound around a core to make the primary and secondary coils of the transformer. The core can be made of different materials such as iron, ferrite or other magnetic materials.
2. Insulation
   • To prevent short circuits, the coils are wrapped with insulating materials such as paper, plastic film or enameled wires.
3. Mounting
   • The wound coils are mounted on the core and fixed in place using screws or other fastening elements. This step can also include the assembly of other components such as heat sinks or housings.
4. Testing and quality control
   • After assembly, the transformers are subjected to various tests to check their electrical properties and ensure that they meet the required standards.

The materials used in the manufacture of transformers vary depending on the application and specific requirements. Here are some of the commonly used materials:

1. Core materials
   • Iron or steel are the most common materials for transformer cores due to their magnetic properties. Ferrite cores are often used in high-frequency or switching power supplies.
2. Winding wire
   • In most transformers, copper wire is used for the coils due to its good conductivity and heat resistance. Special winding wire types such as stranded wire can also be used for high-frequency applications.
3. Insulation materials
   • Insulation materials such as paper, plastic films, enameled wires or insulating varnishes are used to insulate the coils and prevent short circuits. The choice of insulation material depends on the requirements for dielectric strength, heat resistance and other factors.
4. Housing materials
   • The transformer housing can be made of different materials such as metal, plastic or a combination of both, depending on the requirements for mechanical strength, protection against environmental influences and heat dissipation.

It is important to note that the exact materials of transformers can vary depending on the application and industry.

Transformers play an important role in energy conversion and transmission. They are used to increase or decrease the electrical voltage and thus improve energy efficiency in the transmission of electrical energy.

When transmitting electrical energy over long distances, it is more efficient to increase the voltage as this reduces the current. Transformers increase the voltage to the level of high-voltage lines in order to minimize the current flow and reduce energy loss during transmission.

When the electrical energy is distributed in residential and commercial areas, the voltage is then reduced again so that it can be used safely and efficiently in households and businesses. This is where transformers are used in substations.

Transformers consist of coils that are closely coupled together. Magnetic induction transfers the energy from one coil to the other and transforms the voltage accordingly. Transformers therefore play a crucial role in the conversion and transmission of electrical energy.

Transformer technology is a key element in electrical energy transmission and distribution. Various developments and trends can be expected in the coming years:

1. increased efficiency: the efficiency of transformers is expected to be further improved in order to minimize energy loss during transmission. New materials and construction methods could help to increase efficiency.

2. smart grids: The increasing integration of renewable energies requires intelligent power grids that enable efficient transmission and distribution. Transformers will play an important role in integrating these renewable energy sources by adjusting voltage and controlling current flow.

3. compact transformers: Space is often a limiting factor in urban areas. Therefore, compact and space-saving transformers are expected to be developed to reduce space requirements and increase placement flexibility.

4. smart transformers: By integrating sensors and communication technologies, transformers can be monitored and controlled in real time. This enables better diagnosis of problems, preventive maintenance and optimized performance.

5. improved insulation: The insulation of transformers plays an important role in the safety and reliability of the system. The development of advanced insulation materials and technologies is expected to improve the performance and longevity of transformers.

6. weight reduction: Transformers are often heavy, which can make transportation and installation difficult. By using lighter materials and advanced construction techniques, the weight of transformers could be reduced, making them easier to handle.

7. electronic transformers: Traditional transformers are based on electromagnetic induction. Electronic transformers are expected to gain importance, using semiconductor devices to control the voltage and current flow. These could be more compact, efficient and precise than conventional transformers.

These developments and trends will help to improve the efficiency, reliability and flexibility of transformer technology and enable more sustainable energy transmission and distribution.

Transformer manufacturers worldwide primarily adhere to IEC 60076 and IEEE C57. These standards define design, insulation coordination, temperature rise, test procedures, and short-circuit resistance.

In addition, regional specifications such as EN 50588 apply to loss classes. Technical differences arise in cooling types, tap changers, and test sequences.

The high-voltage transformer application requires graduated insulation systems in accordance with IEC 60071 with BIL values (Basic Insulation Level) between 75 kV and 1550 kV, depending on the rated voltage. Oil-paper, SF₆ gas or solid insulation with defined creepage and clearance distances are used.

The control of transient overvoltages caused by switching operations or lightning strikes is critical. Insulation coordination takes into account statistically occurring overvoltages and defines protection levels using surge arresters. Partial discharge measurements in accordance with IEC 60270 validate the insulation quality, with limit values

Energy conversion in the transformer is based on electrodynamic coupling via an alternating magnetic field, whereby electrical energy is converted into magnetic flux density $B$ on the primary side and fed back on the secondary side. To minimize iron losses, highly permeable, grain-oriented electrical laminations are used, which suppress eddy currents at high frequencies and optimize magnetic hysteresis thanks to their insulating coating.

In addition, ohmic losses in the copper winding and leakage inductances limit the efficiency of the energy transfer. Through precise winding geometry and consideration of skin and proximity effects, engineers ensure that the degree of coupling is maximized in order to guarantee a stable voltage ratio and minimal thermal dissipation even under transient load conditions.

In transformer winding, the leakage inductance correlates directly with the geometric arrangement of the windings and the distance between the primary and secondary windings. An uneven distribution of the wire or a loose winding method results in magnetic field lines that do not couple both coils, which reduces efficiency and has a negative effect on voltage regulation when the load changes.

To minimize these parasitic effects, engineers often rely on the technique of sandwich winding (interleaving), in which the windings are divided into several layers and interleaved. This method reduces the effective thickness of the winding space and optimizes the magnetic coupling field, which can significantly reduce both the leakage inductance and the winding capacitances for high-frequency applications.

They are primarily used where large amounts of electrical power have to be transported over long distances or provided for industrial high-voltage processes. High-voltage transformers are used in substations to transform the generator voltage of power plants to the highest voltage level (up to 380 kV), which reduces the line current and thus minimizes the ohmic transmission losses ($P = I^2 \cdot R$) in the power grid.

They are also essential in heavy industry for the operation of electric arc furnaces and in medical technology for particle accelerators and X-ray systems. In these areas, the transformers must meet extreme requirements for insulation resistance and thermal management, often using special insulating oils or cast resins to guarantee dielectric safety and efficient heat dissipation under continuous load.

In transformer winding, the insulation between the layers and windings is crucial in order to prevent partial discharges and winding short circuits at high field strength gradients. Engineers must match the insulation class (e.g. class F or H) to the continuous thermal load and use materials such as polyimide films or reinforced pressboard papers. These barriers ensure the required creepage distance and air gap in accordance with DIN EN 61558, especially for high-frequency transformers with high transient loads.

In addition, impregnation or vacuum encapsulation technology plays a key role in eliminating air pockets within the winding, which would reduce the corona resistance. The combination of enameled wire insulation and additional barrier insulation defines the dielectric integrity of the system. A precise design of the transformer winding insulation, taking into account the fill factor, is therefore essential to ensure the required test voltage between the primary and secondary circuit without thermal bottlenecks (hotspots) in the long term.