Transformers Chokes, Passive filters.

New quality of transformation

Products

Transformers

TRAFECO’s product range includes high-quality low- and medium-voltage, single- and three- phase transformers. Our transformers find numerous industrial applications operating in the harshest environments and all climate zones. A controlled production process and the use of materials with the highest technical parameters in production allow us to supply transformers for medical, marine, railway and mining applications. Our transformers supply, among other things, operating theatres and treatment rooms in hospitals, work in the drive systems of rail vehicles and provide a source of energy for longwall shearers. The parameters of our transformers comply with the requirements of European standards, e.g. EN/IEC 61558; EN/IEC 60076 and the regulations of the relevant Classification Societies. We supply transformers to many demanding customers of European and global importance. High standards of quality control, innovative design and construction solutions combined with the use of modern magnetic and construction materials allow us to meet the technical requirements of all our customers.

At TRAFECO we use the transformer manufacturing technology that has been proven over many years of experience. As part of internal development work and thanks to cooperation with numerous research centres, we introduce our own innovative design and technological solutions into production, significantly improving the parameters of our transformers. We systematically work on the development of our transformers, thus increasing their competitiveness, and we expand our product range with new types of devices. Transformers manufactured at TRAFECO are ergonomic, assembly-friendly and maintenance-free devices during their lifetime.

A professional and committed staff and a group of specialist engineers provide the company with a market advantage. We are ready to design and deliver to our customers custom transformers with innovative constructions, meeting unusual design or technological requirements.

Chokes

Core induction chokes and coreless inductors are a large group of TRAFECO products. We design and supply chokes and coils that work in many industries. We can make an inductive component designed to work in almost any industrial application. Numerous applications in different operating conditions and applications mean that chokes have diversified in terms of performance and design. Chokes are components that operate under extremely different conditions and forcing depending on the application. Power electronics brings a number of applications for smoothing and energy storage chokes where they are subjected to high frequency components of the current. This meant that the choke and core design had to be changed to limit the additional losses from high frequency currents. For technically challenging applications, we have developed the modern low-loss CoreECOTM bonded multi-slit core technology. CoreECOTM’s low-loss, multi-slot core makes it possible to reduce losses occurring in the core — near the gaps and in the choke winding and structure.

Drive system chokes installed at the input and output of inverters operate in the presence of higher voltage and current harmonics. The action of harmonic frequency currents on the choke core and winding causes the occurrence of additional eddy current and hysteresis losses. Furthermore, in chokes, especially at high power and higher frequencies, the phenomena causing additional losses — skin effect and proximity effect — become more pronounced. . The design of the choke windings and the core shall as far as possible take account of these interactions. The windings of the chokes have a special design to reduce losses and mitigate the mentioned impacts. The CoreECOTM multi-slot core is excellent at reducing losses from harmonic currents.

Similar effects occur in chokes used in power generation and reactive power compensation or filtration. Inductive components operating in harmonic filters are required to have their inductance characteristics as a function of current as linear as possible. Chokes with cores of magnetic materials are subject to the natural ability to saturate the magnetic circuit. Under such conditions, maintaining a linear inductance path is very difficult and requires special technological procedures to hinder local saturation of the core. Designing core chokes with extended linearity of inductance characteristics requires lowering the operating induction in the core which leads to increased mass and size of the component. If there is an absolute need to maintain the linearity of the magnetic characteristics, the best solution is to use coreless coils. AirECOTM type coreless coils have linear inductance characteristics over the full load current range. Air coils find numerous applications in filtration and circuits with significant overloads. The coils are designed in two varieties – natural air cooling and forced air cooling. Due to the lack of a flux focusing core, the coils interact strongly with ferromagnetic structures in the vicinity. A ferromagnetic coil housing or a massive structure in the immediate vicinity can affect the inductance value and the coil’s own losses. All inductive components can be supplied in enclosures with the required degree of protection. Factory mounted chokes and coils are designed to operate in a limited cooling space and the housing material takes inductive influences into account.

Filters

SinECOTM passive electric passive filters and TRAFECO filters, are dedicated for use in drive systems powered and regulated by voltage inverters. Despite the undeniable advantages of inverter drives, the modulated output signal is often a source of adverse effects on the power cable and the regulated motor. High keying frequencies and the accompanying high steepness of the du/dt voltage pulses are the cause of voltage stress in the insulation of the supply cable and the motor. Large du/dt steepnesses are a common cause of cable or motor damage. High frequencies of the inverter output voltage result in higher values of ground and screen currents. The solution to these technical problems is to use a sinusoidal filter of the SinECOTM type at the output of the inverter. They restore the sinusoidal shape of the inverter voltage by limiting the voltage harmonic amplitudes to THDu values below 5%. This protects the motor and cable insulation system and eliminates dangerous reflection voltages on the motor. A passive sinusoidal filter consists of an inductive choke and appropriately selected capacitors. Capacitors for this application are ordered in a special design to withstand the unfavourable high du/dt voltage steepness. Chokes, on the other hand, are made with the low-loss CoreECOTM multi-slot technology, which significantly reduces the flux of the core of the choke, which has the effect of reducing the additional loss and limiting the acoustic field around the choke.

Most popular inverters even of high power have a rectifier in the input circuit in a six-pulse bridge arrangement. Such a rectifier draws a relatively strongly distorted current from the mains during operation. The harmonics of the mains current also place a heavy load on the mains transformer windings. Because of the large number of non-linear loads in plants, power transformers are often oversized, taking into account the additional losses due to current harmonics (K factor). ThdECOTM type harmonic filters are devices designed to operate in the supply circuit of typical inverters with a six-pulse input rectifier. These filters limit the harmonic content of the current drawn from the mains to less than 5% THDi, allowing compliance with IEEE 519-1992 and PN-EN 61000-3-12 standards. In facilities where harmonic filters are applied to large drives and non-linear loads, it is not necessary to oversize the mains transformer. Harmonic filters protect the power transformer windings from overload by current harmonics.

SinECOTM sinusoidal filters and ThdECOTM harmonic filters can be supplied in IP23, IP44 or IP54 rated housings. The housings are sized to guarantee cooling and correct operation of the equipment. In the case of self-installation of filters in sealed casings, the casing must be selected so that its surface can absorb the losses generated by the filter. Upon agreement, we can design and manufacture filters for any voltage level, non-standard operating conditions in any climatic zone.

Enclosures

TRAFECO’s offer is supplemented by enclosures designed for mounting transformers or inductive components. The enclosures are made of ferromagnetic sheet steel, protected against corrosion with powder varnish. There are several variants of free-standing and wall- mounted enclosures with different dimensions and degrees of protection. Standard enclosures are made in protection grades IP23, IP44 and IP54. The standard colour of enclosures is RAL 7035. By agreement, the transformer can be supplied in a housing with the required degree of protection and colour.

Enclosures made of ferromagnetic steel sheets provide an easy route for the magnetic scattering flux that occurs around transformers and choke. In the case of high-power transformers and chokes with intense flux dissipation, the conduction of the flux through the housing sheets leads to heating of the housing due to the occurrence of hysteresis and eddy current losses in the housing material. This phenomenon occurs intensively only for elements with high scattering flux. In the vast majority of applications, the enclosures do not heat up additionally from the scattering field. In extreme cases where there is a risk of inductive heating of the enclosure (high-power coreless coils, medium-frequency chokes), it is possible to make the enclosure from paramagnetic or aluminium sheet metal which does not conduct magnetic flux.

When using IP44 and IP54 sealed enclosures, the cooling efficiency of a transformer or choke operating inside depends mainly on the proportion of the external surface of the enclosure, the ambient temperature and the losses emitted by the device. Transformers intended for use in sealed enclosures are designed with special regard to limiting the losses dissipated, and the enclosure for them is selected individually.

Special equipment

In addition to catalogue transformers and inductive components, we design and supply our customers with customised transformers, chokes, inductors and filters, tailored to the needs of the project and the customer’s individual requirements. We also undertake production of complex, non-standard devices based on agreements with the customer.