Transformers, Chokes, Wound parts

Transformers of this type are manufactured in many variants and modifications. Based on our clients’ needs, we deliver
transformers with atypical electrical parameters, which include higher insulation voltage, abnormal current, high
voltage, saturation levels, insertion of a magnetic shunt, and other non-standard technical requirements. This
presents a wide variety of applications for the transformers.

Using the manufacturer's newly developed technology is minimizing some of the undesirable effects.
For example:
- winding in flat wire in upright;
- winding in aluminium wire;
- winding with forced cooling;
- winding with air channels.

A standard feature of our transformers is bi-metallic reversible protection against instant and long-term
overload, or irreversible thermal fuse.

3-phase transformers are supplied in two basic types:
3UI with mounting clips (38 – 15500VA)
3UN mounting clips (750 – 500kVA)

The connection of the primary and secondary winding of these transformers can certainly be combined to satisfy
the needs of the customer. Connection star/star, delta/delta, star/broken star.
Individual versions are available in many variations:
- Autotransformers (200 – 30000 VA) are also available with 3UN-UNICORE cores where the compact core contributes to the small form factor of the transformer.
- Special-purpose transformers EN, insulation safety insulation units for mobile applications rated 16 kVA – 45 kVA.

All our products naturally offer modification of all parameters to meet the customer’s requirements.
Various Ingress Protection ratings are offered for specific transformer variations.

High-rating units are also available in an aluminium variant with copper terminals with following advantages:
- Resistance to changes in temperature: The coefficient of thermal expansion of aluminium is close to that of the casting resin and in abrupt changes of temperature, e.g. powering on of a cold transformer, no tension is generated on the border of the resin and metal. The thermal expansion of copper is nearly twice as much. When copper is used, the heat expansion of the resin needs to be modified with a proper filler, typically glass fibre. The border between the copper and resin might require a different treatment, which is always the modification of insulation system and
is not required in the case of aluminium variant.
- The lower price of material results in a lower price of the finished transformer.
- Lower transformer weight and identical rating as copper variant.

Single-phase toroidal transformers up to 4000 VA
3-phase toroidal transformers up to 2000 VA.
Toroidal transformers for audio amplifiers, impedance modulation, etc.

Compared to traditional EI or M transformers, toroidal transformers offer a number of advantages that have a positive effect on the quality of the equipment in which they are used.

Their typical applications include:
- halogen lights and lighting equipment
- pools and pool equipment
- elevators and lifting equipment
- consumer and electrical engineering, audio-visual equipment
- sources of current and voltage
- healthcare equipment and any other application where excellent electrical properties of components is required
- coupling of the primary and secondary winding with small dispersion inductance
- low noise level 50 Hz
- lower no-load current
- design of power supply sources with low internal resistance
- Optional high number of shunts and independent windings lower size and weight, time savings during installation

Standard design:
- in the basic version (5 – 4000 VA)
- mounting centre hole
- drilled hole
- brass thread
- holder for the DIN rail

We offer various designs and types of casing:
- for the installation in printed circuit boards (20 – 100VA),
- in a box with litz-wire terminals (5 – 600VA),
- with IP56 rating (20 – 500 VA) in an installation box
- with IP54 rating (50 – 900 VA) in an installation box
- with IP68 rating (50 – 600 VA)

Isolating transformers 230V/230V in an installation box (50 – 200VA).

3-phase toroidal transformers (200 – 2000 VA). Toroidal
transformers for audio amplifiers, impedance modulation, etc.

Toroidal transformers may be protected with a melting or thermal fuse, in a return or non-return design.

Application of NTC or PTC thermistors offers variable resistance load.

We also offer toroids wound from copper foils.

Filtrating, Compensation inductors for starting, traction and other purposes.

In the long run, industrial plants have been demonstrating an increase of controlled inductance equipment with a high frequency of activation that are activated for a very short time or they are activated in rapidly recurring intervals.
This applies to equipment used in pressing, spot welding, cutting, centrifugation, induction heating or loads caused by starting and braking of electric motors. The time intervals range from several periods of mains frequency up to tens of seconds. This manifests as variance in voltage and a higher number of harmonic frequencies. Contactor compensation in substations in these situations is not capable of responding to such short variance of reactive power; however, electricity meters also record that consumption of reactive power. In situations where most of the consumers in the measured consumption exhibit this type of load, the contactor compensation method cannot be used to observe the required cosφ values. Obviously, the user of this contacting technology must also meet the connectivity requirements for connection to the distribution grid. In practice, therefore, simple cases are resolved by direct compensation, e.g. a set of high-performance presses with relatively long operation
cycles, as well as demanding requirements for compensation of an automatic machine which uses 4 periods (80 ms) to work on a weld.

In the long run, industrial plants have been demonstrating an increase of controlled inductance equipment with a high frequency of activation that are activated for a very short time or they are activated in rapidly recurring intervals.
This applies to equipment used in pressing, spot welding, cutting, centrifugation, induction heating or loads caused by starting and braking of electric motors. The time intervals range from several periods of mains frequency up to tens of seconds. This manifests as variance in voltage and a higher number of harmonic frequencies. Contactor compensation in substations in these situations is not capable of responding to such short variance of reactive power; however, electricity meters also record that consumption of reactive power. In situations where most of the consumers in the measured consumption exhibit this type of load, the contactor compensation method cannot be used to observe the required cosφ values. Obviously, the user of this contacting technology must also meet the connectivity requirements for connection to the distribution grid. In practice, therefore, simple cases are resolved by direct compensation, e.g. a set of high-performance presses with relatively long operation
cycles, as well as demanding requirements for compensation of an automatic machine which uses 4 periods (80 ms) to work on a weld.

The contactless compensation system is also very often used in situations where the temporary effects of activation must be ruled out. Such requirements can be seen, for example in hospitals.

These are the reasons why we divide and manufacture these types of inductors in variants specified by the customer (installation in a distribution cabinet, casting-in in a form or case, waterproofing, with brackets or mounting eyelets, Al/Cu)
- Filtration inductors 50-60 Hz
clear the line of voltage from unwanted harmonic
phenomena generated during equipment switching.
- Compensation inductors 50-60 Hz
3-phase filtration inductors, adapted to the output, which in connection with condensers of required capacity provide compensation of reactive power.
- Starting
Their purpose is to modify the startup curve of electric motors. Their main application is with the manufacturers of simple gantry cranes and other lifting equipment.
A special modification of the positioning system in these inductors permits the inductance to be changed by modifications of the gap between the cores, thereby adjusting the optimum startup curve of the motor.
- Traction
A single-phase air coil that is used in traction systems for filtration, straightening, commutation, etc.
- Air
This group includes, for example, inductors for frequency splitting in speaker system crossovers and antennas
- Special – we manufacture according to our customers’ specifications.

They are manufactured according to designs prepared by us or by the customer. Very often they are transformers for various sources with special
integrated circuits. The most famous are manufactured by Philips (VIPER), ST, etc. We produce wound components for single-action (FLYBACK), permissive (FORWARD) and dualaction, resonating, quasi-resonating converters and their modifications.

Magnetic circuits typically use ferrite cores with mass parameters N48, N67, N87, N97 and others, which are suitable especially for high-output applications. For the most part, they are types ETD, Ul, EF, RM, EP, EFD, ELP, PQ, P or E.

A limitation for the ferrite cores is the necessity to observe the Curie temperature, which lies in the vicinity of 180 °C.
Based on our experience, we do not design HF components the operational temperature of which exceeds 100°C.
Ferrite cores with a gap may be replaced with iron powder toroidal cores.

Although the loss in iron powder toroids is approximately 10 times higher, they radiate thermal energy with their entire surface, which makes them equal to ferrite circuits with gaps. Especially if the mechanical components for removal of heat are well made, they are a very interesting commercial article. Our design experience prevents us from exceeding the operating temperature of 100 °C.

We deliver chokes:
- toroidal filtration inductors (0.5-25 A)
- toroidal operational inductors (6-25 A)
- toroidal inductors with current compensation (0.3-32 A)
- filtration inductors with E core (25 A)
- special high-performance inductors
- variant in horizontal or M cabinets

Chokes are manufactured to meet the needs of our customers. The choice of material of the magnetic circuit is optional as long as all permitted electrical parameters are observed.

In the case of inductors and transformers for HF applications, the operating frequency lies in the band 10-200 kHz. They are manufactured to design prepared by us or by our customer.

Transformers for HF applications are a highly specific domain. Each designer of HF circuits has different requirements and also uses different excitation circuits. Unification in this domain is very complicated. That is why we offer these components only upon request and not in a series.

KAS type transformers are designed as slide-on units, KLW type features a thread.
The standard value of secondary current is 5A (1A upon the customer’s request) in accuracy classes 0.5 and 1 (0.2S; 0.2; 0.5S available upon request).

Basic classification of measuring transformers:
- Low-voltage – measurement of voltage
- Low-voltage – measurement of current
- Medium-voltage – measurement of voltage and current
- Closed current probe with a Hall effect sensor
- Equipment for measuring AC/DC current with a Hall effect sensor
- Special sensors for AC voltage and current

Maximum operating voltage is 720V, testing voltage is 3kV, 50Hz,I term=60xln, I dyn=150xln, temperature in class “E”.

Secondary terminals are located under a transparent cover, i.e. the transformers may be sealed and are suitable for recording consumption of electricity.

Basic types of measuring transformers:
- Current measuring transformers type KAS1 to KAS7 – SLIDE-ON. Primary current 60 to 4000 A.
- Current measuring transformers KLW 3/3 primary current 15-200 A.
- Current measuring transformers KWZ3 to KWZ7 primary current 0.5 -15 A.
- Transformers of this type are connected into the secondary winding of the main current transformer.
- Current measuring transformers KWS5 to KWSZ7 (combination transformer).
- Medium-voltage transformers for measuring voltage or current. For measuring voltage and voltage in 36kV voltage level.
- Closed or ring-type current probe with a Hall effect sensor for installation in PCB and switchgear, primary current 25-1200 A.
- Sensors of AC voltage and current are designed to control electronic systems used in all types of electronic equipment in the slide-on
- And non-slide version, in modifications for the printed

- Dry Distribution, Power and Rectifier Cast Resin Transformers or with impregnated winding
Power rating 25-2500 kVA, Rated voltage to 35 kV
- Dry Special Transformers for different industry application, e.g. for furnace, earth, and other
- Dry Filter reactors, Starting reactors, Compensative reactors, Air core smoothing reactors, Limiting reactors, Special reactors and other
- Oil Distribution Hermetical Transformers (or with oil conservator),
Power rating 25-2500 kVA, Rated voltage to 35 kV
- Repairs of Dry Transformers and Reactors

MV Transformers
3-phase Dry Distribution, Power and Rectifier Cast Resin Transformers or with impregnated winding, Power rating 25- 2500 kVA, Rated voltage to 35 kV, Enclosure IP00, IP23, IP31 (indoor installation) also IP43, IP54 (outdoor installation), Winding Al (or Cu). Standard and reduced losses, Isolation class F (possib. H), Cooling AN (Air Natural), possibility too AN/AF

1-phase and 3-phase Dry Power and Rectifier Cast Resin Transformers or with impregnated winding, Power rating to 2,5 MVA, Rated voltage to 35 kV, Enclosure IP00 also in box, winding Al (or Cu), Isolation class F (possib. H), Cooling AN (Air Natural), possibility too AN/AF

3-phase Oil Distribution Hermetical Transformers (or with oil conservator), rating 25-2500 kVA, Rated voltage to 35 kV, Cooling ONAN, standard accessories

MV Reactors
Dry Reactors – Impregnated & Cast Resin at special cases, for indoor installation, with or without Fe-core Rated voltage to 22 kV, Isolation class F, Cooling AN