Wound magnetic cores are one of the most important components for the production of electric machines and their quality determines the parameters of the final product.
We offer the following types of magnetic cores
- Toroidal cores
- Wound divided cores
- Electrical steel - lamination
- Unicore
- Nanocrystalline cores
Used electrical steel:
- ​Strip thickness 0,10mm, 0,15mm, 0,18mm, 0,20mm, 0,23mm, 0,27mm, 0,30mm and 0,35mm
- Coil widths from 5mm to 1000mm
- Frequency from 50Hz to 20kHz


To measure magnetic properties of  cores, we are equipped with special instruments. These values are measured continuously in the entire range of the alternating magnetizing characteristics limited merely by the maximum power of measuring instrument. All results can be printed on the measurement protocol or it is possible to process the measured values further in the form of tables and graphs directly on the computer. We do 100% tests of all our cores and the measuring process is controlled and recorded.

The use of magnetic cores

Wound magnetic cores produced by our company are used for construction of:
- Network transformers
- Measuring transformers
- Safety transformers
- Instrument transformers
- Power transformers
- Output transformers
- Potential transformers
- Pulse transformers
- Special transformers
- Single-phase and three-phase distributive transformers
- Single-phase and three-phase chokes
- Conventors
- Inductors
- Impulse transformers etc.
Non-grain oriented electrical steel (CRNGO)
- Strip thickness, 0,35mm, 0,50mm, 0,65mm
- Coil widths from 5mm to 1000mm,
The following properties are evaluated:
- Intensity of the magnetic field Heff (A/m)
- Magnetic induction Bmax. (T)
- Core losses P (W)
- Amplitude permeability etc.
The control system is based on the following main points:
- Selection of electrical steel, which is based on its magnetic and mechanical quality
- Dimensional control for winding cores
- Thermal process control
- 100% final quality test ensures dimension accuracy and guarantees, that the limits of magnetic values are met.
- Packaging control


What are toroidal cores?
Toroidal cores are wound from grain oriented silicon steel, mostly into a circular shape. 
Production scope of toroidal cores:
- Outer diameter of the core d1 = 15 - 1000 mm
- Inner diameter of the core d2 = 10 - 950 mm
- Core height h = 5 - 100 mm
We deliver toroidal cores in various material grades:
- Thickness 0,18, 0,23, 0,27, 0,30, 0,35mm, as M165-35S, M150-30S, M140-27S, M110-27S,
- HIB grades, thickness 0,20, 0,23, 0,27 or 0,30mm, as M085-23P, M090-27P, M095-27P, M100-23P, M103-27P, M105-30P, H111-30P
- Material for higher frequency 400Hz - 20kHz in thickness 0,10mm - label GT100,
- "Special material" for current and voltage transformer with the highest class of precision
Using toroidal cores:
TToroidal cores made of high permeability materials are used where high sensitivity of induced voltage in the secondary winding to changes of magnetising current is required and where minimal distortion of the transmitted signal is required. These cores are also used for chokes with a high inductance. Very low losses during magnetizing by alternating current is often used as well.
Toroidal cores for high frequencies are used where magnetizing current of the core has a medium or high frequency, usually of  ranges of tens up to hundreds of kHz. At higher frequencies the permeability of material is very low, and its losses increase enormously. As an example of such use can serve cores for antijamming chokes for circuits with thyristors and triacs, high frequency and switching powers or telecommunication transformers.
We can produce and deliver them as
- ​Not impregnated
- Lightly impregnated with polyurethan varnish
- Fully impregnated wit epoxypolyurethan enamal, Type FIX
- Cores with cutted edges (bevelled) in angle of 45° or radius
Impregnation of toroidal cores with epoxy
It is used as a protection for toroidal cores, provides strength to the core, secures them against mechanical damage and enables simpler post-processing.
Protection of toroidal cores by comaxitization
Comaxiting is the electrostatic application of EPOXY - POLYESTER powder No. 2310 and subsequent firing at 180°C. For toroidal cores that are used by the electrical manufacturer of the machine, the copper wire is wound directly without bandaging, the 2nd layer is also applied in order to achieve high-quality insulation in the required thickness of 0.3 - 0.4 mm by double comaxing.
We have toroid meters
The following properties are evaluated:
- Intensity of the magnetic field Heff (A/m)
- Magnetic induction Bmax. (T)
- Core losses P (W)
- Amplitude permeability etc.


What are divided cores?
C-cores are produced by winding a strip of  CRGO steel on a rotating mandrel. After having been wound and glued by a epoxy resin, the core is then cut into a few pieces. 
C-cores properties depand on the following factors:
- Geometry of magnetic cores
- The size of air gap between cutted surfaces
- Quality of used CRGO steel
To measure magnetic properties of  C-cores, we are equipped with special instruments. We do 100% tests of all our cores and the measuring process is controlled and recorded.
- Intensity of the magnetic field Heff (A/m)
- Magnetic induction Bmax. (T)
- Core losses P (W)
- Amplitude permeability etc.
C-cores can be produced in different types and shapes:
- ​One step (one strip width)
- Cruciform (few steps/different widths)
- Single-phase
- Three-phase
- Circular, oval or rectangular shape
The quality of cutted surfaces is very important for function of final C-core (transformer):
- Common quality of cutted surfaces up to 30 μm TYPE "A".
- Grinding cutted surfaces TYPE "C", done on grinding machine
C-core examples:
For the cores wound from the tape thickness of 0.35 (grade N) maximum allowed measuring losses and intensity of magnetic induction Bmax = 1,5T and frequency 50 Hz in four groups according to the following table are guaranteed:


For cores from the belt thickness 0.35 mm (grade N) the highest permissible specific loss values ​of 2.5 W/kg are guaranteed at a magnetic induction Bmax = 1.5 T and a frequency of 50 Hz in accordance with DIN 41309 and IEC 329 standards.
For cores wound from tapes with a thickness of 0.10, the highest value of specific losses of 15 W/kg is guaranteed at magnetic induction Bmax = 1.5 T and frequency 400 Hz. At the request of the customer, we supply certificates of measurement of magnetic properties.


Unicore cores and their definitions
Unicore cores belong to the family of magnetic cores, and there are more than 10 different types of them. UNICORE is one of the new cores for magnetic circuits, and its technology was developed only in 1997 with the aim to simplify the manufacture technology and to reach better parameters of transformers. Thanks to their construction UNICORE cores are able to replace almost all classical stacked cores. Because of their simplified construction there is no need for time- and cost- consuming production process, and therefore favourable price and short delivery time are achieved. At assembly the existing types of coil forms can be used, and therefore there are no changes in transformer construction needed.
Types of Unicore:
DUO, DG - with a split gap
UNCUT - cores without a dividing gap
BUTT - produced as C cores
- ​Cores have a corner of 30°, 45° or 90°. New Types of Unicore cores are permanently developed, see our catalogue.
- Material of any quality of grain-oriented steel of thickness from 0.10 mm – up to 35 mm is used. It is also possible to use non grain-oriented steel. Unicore cores can weigh up to 1500 kg with a maximum height of 300 mm.
Unicore and its advantages:
Therefore it is possible to economize on both the weight of magnetic circuits and amount of copper used. Advantages of Unicore cores: low specific losses, smaller amounts of copper used, simple assembly, favourable price, core banding is not necessary, short delivery time.
Cores can be delivered annealed and unannealed . Subsequent annealing of the cores reduces the losses by 10 to 30 % according to the core dimension. 
Guarantee of quality is a prerequisite for success and therefore a systematic inspection of the Unicore production is performed.
Unicore is defined by the following parameters:
- Window length (WL)    
- Window width (WW)
- Strip width (SW)              
- Built up (BU)
- Strip thickness (ST) 
- Corner angle


Grain oriented electrical steel (CRGO):
- All types of grades
- Strip thickness 0,10mm, 0,15mm, 0,18mm, 0,20mm, 0,23mm, 0,27mm, 0,30mm a 0,35mm
- Coil widths from 5mm to 1000mm, possible to split on our slitting machine,
- Frequency from 50Hz to 20kHz
Non-grain oriented electrical steel (CRNGO):
- All types of grades
- Strip thickness 0,35mm, 0,50mm, 0,65mm
- Coil widths from 5mm to 1000mm, possible to split on our slitting machine
Magnetic properties of grain oriented electrical steel:
EN 10107 mm 50 Hz W/kg 50 Hz W/kg T
M 110-23 S 0,23 0,73 1,10 1,78
M 120-23 S 0,23 0,77 1,20 1,78
M 127-23 S 0,23 0,80 1,27 1,75
M 120-27 S 0,27 0,80 1,20 1,78
M 130-27 S 0,27 0,85 1,30 1,78
M 140-27 S 0,27 0,89 1,40 1,75
M 130-30 S 0,30 0,85 1,30 1,78
M 140-30 S 0,30 0,92 1,40 1,78
M 150-30 S 0,30 0,97 1,50 1,75
M 140-35 S 0,35 1,00 1,40 1,78
M 150-35 S 0,35 1,05 1,50 1,78
M 165-35 S 0,35 1,11 1,65 1,75
Guaranteed magnetic properties CRGO – HIB grades: