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Ing. Karel Künzel, CSc.

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Applicability of magnetic field for directed orientation of steel fibres in high-performing cementitious composites

  • Authors: Carrera, K., Ing. Karel Künzel, CSc., prof. Ing. Václav Papež, CSc., Konrád, P., Mára, M., Fornůsek, J., Kheml, P., Sovják, R.
  • Publication: The International Journal of Computational Methods and Experimental Measurements. 2022, 10(2), 131-145. ISSN 2046-0546.
  • Year: 2022
  • DOI: 10.2495/CMEM-V10-N2-131-145
  • Link: https://doi.org/10.2495/CMEM-V10-N2-131-145
  • Department: Department of Electrotechnology
  • Annotation:
    This paper explores the practical possibility of using a magnetic field to orient steel fibres in a fresh concrete matrix. This process leads to preferential orientation, which increases the desired mechanical properties of the hardened material. In general, this paper focuses on the technical aspects of the orientation process and identifies key areas, such as the strength and shape of the magnetic field, velocity of the sample’s passage through the magnetic field and viscosity of the materials. A proto-type orienting apparatus was constructed with different permanent magnet systems to evaluate their performance. An ultrasound gel and a cementitious matrix were used as a medium for the fibres. Numerical simulations were created to further understand the effects of the magnetic field’s strength and shape. The final orientation of the fibres in hardened concrete was evaluated using Q factor measurements, X-ray scans and bending tests. A sufficiently strong magnetic field can be used to orient fibres in fresh concrete.

Concrete lintels reinforced with steel fibres oriented by a magnetic field

  • DOI: 10.14311/AP.2022.62.0531
  • Link: https://doi.org/10.14311/AP.2022.62.0531
  • Department: Department of Electrotechnology
  • Annotation:
    This paper explores the possibility of applying the technique of magnetic orientation of steel fibres for manufacturing a concrete structural element of realistic dimensions, compared to small laboratory specimens. This technique could be a part of an answer to the current need for faster and automated production in the prefabrication industry. The examined specimens have dimensions of commonly used lintels in construction, 80 mm × 100 mm × 980 mm. The properties of specimens with magnetically oriented fibres are compared with same size specimens prefabricated conventionally. The orientation of fibres has been confirmed by Q-factor non-destructive testing method using a measuring coil. All specimens were tested with a four-point bending test. The specimens with oriented fibres show a significantly higher flexural strength, by 150 %, than specimens produced conventionally with the same volume of fibres.

Flexural strength of fibre reinforced concrete in relation to the angle of magnetically orientated fibres

  • DOI: 10.1051/matecconf/202236405017
  • Link: https://doi.org/10.1051/matecconf/202236405017
  • Department: Department of Electrotechnology
  • Annotation:
    This paper focuses on high-performance fibre-reinforced concrete and its flexural strength concerning fibre orientation. The orientation is provided by a fully controlled special device. This device can align the fibres in fresh concrete using a magnetic field. The specimens are inserted into the device at different angles to ensure different fibre orientations concerning the longer side of the sample, which corresponds to the direction of the main tensile stresses. Specifically, angles of 0 °, 30 °, 60 ° and 90 ° are tested and compared with each other and with reference specimens that are not exposed to a magnetic field. All samples are measured by a non-destructive method. This method was developed in our previous research and is based on measuring the quality factor Q of a measuring coil using an impedance meter. The samples are inserted into a measuring coil connected to an impedance meter. Flexural strength is obtained from the results of a threepoint bending test. All samples are tested until complete failure.

Magnetic properties of steel fibres commonly used in concrete

  • DOI: 10.1016/j.matpr.2022.04.134
  • Link: https://doi.org/10.1016/j.matpr.2022.04.134
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with measuring of magnetic properties of selected steel fibres commonly used in concrete. The results in relation to the possibility to orient fibres by magnetic field in fresh concrete are explained. The principle of the measurement setup used to obtain the magnetic parameters of the fibres is presented. The measurement setup is chosen to test fibres as they are with only the necessary mechanical shortening for fibres with shaped ends. Furthermore, the results for ten types of commonly used steel fibres from different manufacturers are presented and compared. For overview and control, the measurements on the fibres are supplemented by testing of known materials used in magnetic circuits.

Mechanical properties of high-performance concrete with steel fibres oriented by an electromagnetic field

  • DOI: 10.1061/(ASCE)MT.1943-5533.0004342
  • Link: https://doi.org/10.1061/(ASCE)MT.1943-5533.0004342
  • Department: Department of Electrotechnology
  • Annotation:
    In order to achieve better efficiency of dispersed fibre reinforcement in cementitious composites, manufacturers need to be able to directly control the fibre orientation. The magnetic orientation of fibres is an effective way to align fibres in the desired direction of the main tensile stresses and significantly improve the load-bearing capacity of the composite material. In this study, cementitious composites with different percentages of fibre reinforcement were subjected to the magnetic fibre-orienting process and their resulting mechanical parameters were examined. Also, a non-destructive method was used to evaluate the fibre orientation and volume. The flexural strengths and the capacity to dissipate mechanical energy were improved considerably compared to the reference non-oriented specimens. The non-destructive method was also reasonably accurate to predict these results.

Modeling of rotation of stiff ferromagnetic fiber in non-Newtonian fluid initiated by magnetic field

  • Authors: Carrera, K., Mikeš, K., Ing. Karel Künzel, CSc.,
  • Publication: AIP Conference Proceedings. Melville (NY): AIP Publishing LLC, 2022. p. 1-4. vol. 2425. ISSN 1551-7616. ISBN 978-0-7354-4182-8.
  • Year: 2022
  • DOI: 10.1063/5.0081479
  • Link: https://doi.org/10.1063/5.0081479
  • Department: Department of Electrotechnology
  • Annotation:
    The article deals with the numerical model describing the rotation of stiff ferromagnetic fiber in non-Newtonian fluid initiated by the magnetic field. Simulations in the software ANSYS ® were performed to determine the magnetic force applied to a stiff ferromagnetic fiber. Function expressing moment effects of the magnetic field on the stiff ferromagnetic fiber was obtained by the data from simulations. The paper shows the derivation of the equation describing the rotation of stiff ferromagnetic fiber in a non-Newtonian fluid. Sets of experiments were performed and measured data were used to fit the numerical model.

Quality factor as a tool to measure concentration and orientation of ferromagnetic fibres in sample

  • DOI: 10.1016/j.matpr.2022.04.605
  • Link: https://doi.org/10.1016/j.matpr.2022.04.605
  • Department: Department of Electrotechnology
  • Annotation:
    Fibre-reinforced concrete is a modern composite material. Steel fibres are often used as scattered reinforcement in cement composites. We can achieve anisotropic final products by orienting the fibres, i.e. higher strength in the required direction. One of the ways, how to control the orientation of ferromagnetic fibre in composites, is a non-destructive method based on mutual induction. The advantage of non-destructive testing is, among other things, the possibility of application to fresh cement mixtures. This paper presents a fast and effective non-destructive measuring method of fibres orientation degree and fibre volume in cementitious composites. Furthermore, the measurement of fibres oriented at different angles and different fibre volumes is shown.

Rheological properties of sonogel and comparison with rheological properties of high-performance concrete

  • Authors: Carrera, K., Kheml, P., Sovják, R., Ing. Karel Künzel, CSc.,
  • Publication: Materials Today: Proceedings. Lausanne: Elsevier, 2022. p. 1308-1311. ISSN 2214-7853.
  • Year: 2022
  • DOI: 10.1016/j.matpr.2022.02.160
  • Link: https://doi.org/10.1016/j.matpr.2022.02.160
  • Department: Department of Electrotechnology
  • Annotation:
    This paper deals with the measurement and comparison of the rheological properties of sonogel and high-performance concrete (HPC). Measurements were made with two different instruments. The Mars II rheometer was used to measure the absolute data of the sonogel. Comparative measurements of HPC and sonogel were performed with HAAKE VISCOTESTER iQ. The flow curve test and the stress growth test were performed. The thixotropy behavior of sonogel was investigated as well. The results are presented in the context of the magnetic orientation of fibers in cement composites.

Simulations of the behaviour of steel ferromagnetic fibres commonly used in concrete in a magnetic field

  • DOI: 10.3390/ma15010128
  • Link: https://doi.org/10.3390/ma15010128
  • Department: Department of Electrotechnology
  • Annotation:
    The efficiency of fibre reinforcement in concrete can be drastically increased by orienting the fibres using a magnetic field. However, the parameters of such a field are not immediately apparent, as they depend on the specific fibre reaction to the magnetic field. In this paper, numerical simulations are conducted to study the mechanical torque acting on fibres placed in a magnetic field. The simulations are verified with an experimental setup as well as theoretical relationships. Ten different fibre types, both straight and hook-ended, are examined. The developed model can be successfully used to study the behaviour of fibres in a magnetic field. The fibre size plays the most important role together with the magnetic saturation of the fibre material. Multiple fibres show significant interactions.

Summary of findings on magnetic orientation of fibers in cement composites

  • DOI: 10.1016/j.matpr.2022.01.201
  • Link: https://doi.org/10.1016/j.matpr.2022.01.201
  • Department: Department of Electrotechnology
  • Annotation:
    This article summarizes the findings in newly developed technology – Magnetic Orientation of Fibers (MOF). New incoming technology MOF can easily and effectively reinforce concrete elements in a specific direction with ferromagnetic fibers using a magnetic field. Using this technology, it is possible to provide the required orientation of steel ferromagnetic fibers in a fresh mixture of High-Performance Fiber Reinforced Cementitious Composite (HPFRC) with the help of a magnetic field. This article aims to inform about the existing research that deals with this technology. It summarizes the experiments performed, the development of magnetic field generation devices and fiber alignment measurement equipment.

Electromagnetic Properties of Steel Fibres for Use in Cementitious Composites, Fibre Detection and Non-Destructive Testing

  • DOI: 10.3390/ma14092131
  • Link: https://doi.org/10.3390/ma14092131
  • Department: Department of Electrotechnology
  • Annotation:
    This paper deals with the description, measurement, and use of electromagnetic properties of ferromagnetic fibres used as dispersed fibre reinforcement in composite mixtures. Firstly, the fibres’ magnetic properties are shown, and a method of measuring the hysteresis loop of fibres is proposed. The results from the measurements are presented and a discussion of the influence of measured parameters on the fibres’ orientation in a magnetic field is performed. Furthermore, methods of non-destructive estimation, of their amount and orientation in the composite specimens, are discussed. The main experimental goal of this paper is to show the relationship between this non-destructive method’s results and the destructive flexural strength measurements. The method is sensitive enough to provide information related to fibre reinforcement.

Directed orientation of steel fibres in ultra-high-performance cementitious composite using the magnetic field

  • Authors: Lovichová, R., Takáčová, K., Ing. Karel Künzel, CSc., prof. Ing. Václav Papež, CSc., Mára, M., Fornůsek, J., Konrád, P., Sovják, R.
  • Publication: WIT Transactions on the Built Environment. Wessex: WIT PRESS, 2020. p. 39-49. High Performance and Optimum Design of Structures and Materials IV. vol. 196. ISSN 1746-4498. ISBN 978-1-78466-389-6.
  • Year: 2020
  • DOI: 10.2495/HPSM200051
  • Link: https://doi.org/10.2495/HPSM200051
  • Department: Department of Electrotechnology
  • Annotation:
    Ultra-high-performance fibre-reinforced cementitious composites are one of the key industries in the field of concrete technology. Thanks to their exceptional mechanical properties and significantly improved ductility, they are widely used for various special applications such as defensive and protective structures. In composite materials, it is desirable to place the reinforcement where it is needed and in the direction, it is needed. In fibre-reinforced cementitious composites, this orientation is possible through a magnetic field. In the framework of this study, a prototype device for controlled fibre orientation in a cementitious composite was developed. Mixtures of both cementitious composite and ultrasound gel having similar rheological properties to the cementitious matrix were tested. It has been observed that is possible to control the orientation of the steel fibres and direct the fibres in the desired direction by employing an electromagnetic field.

Analysis of the Measuring Circuit for the OCVD Method

  • Department: Department of Electrotechnology
  • Annotation:
    The article describes the analysis of a possible influence of a measuring circuit on the results of the OCVD method. The influence of further junction parameters on effective carrier lifetime measurements is evaluated, which has not been currently monitored by the OCVD method. Then the influence of the exciting current generator, exciting current waveform and parasitic properties of the generator is searched. A especial emphasis is given on the impedance matching between an analysed PN junction and an evaluating part of a measuring circuit. A simulation algorithm expressing the processes both in the tested junction and measurement circuit was found. The measuring system was implemented in several variants and typical measurements were carried out. For experimentally determined parameters, the simulations, whose results showed a good compliance with the results of the experiments, were performed.

Shunt Quenching and Concept of Independent Global Shunt in Multijunction Solar Cells

  • DOI: 10.1109/JPHOTOV.2018.2828850
  • Link: https://doi.org/10.1109/JPHOTOV.2018.2828850
  • Department: Department of Electrotechnology
  • Annotation:
    We show that two-terminal multijunction cells interconnected by tunnel junctions are fairly immune to individual local shunts, thanks to the shunt quenching. Interestingly, they may still suffer from global shunts. We revise the paradigm of a multijunction cell as a simple serial connection of component cells. This paradigm remains valid only for multijunction cells with laterally conductive interlayers. Instead, a new equivalent circuit is proposed and verified by measurement and simulations. As a main approach, selective illumination is applied and the voltage is measured at the end terminals. The global shunt is seen as a shift from logarithmic to linear intensity response. The presence of tunnel junction is important for an optimum configuration of tandem structures such as metal-halide perovskite with crystalline silicon solar cell.

Actualization of European legislative rules for technical requirements on products

  • Authors: Žáček, J., Ing. Karel Künzel, CSc.,
  • Publication: Sborník XI. koference "Energetické rušení v distribučních a průmyslových sítích". 2014. ISBN 978-80-905933-0-5.
  • Year: 2014
  • Department: Department of Electrotechnology
  • Annotation:
    Harmonization of legislative rules of the EU Member States according to the New Legislation Framework for products placing on the market. Novelty of European EMC Directive 2014 – principal changes, entry into force. Another actual directives applied to the electrotechnical products, required for EU Declaration of conformity – low voltage equipment, ecodesign, restriction of the hazardous substances. Novelty of the Blue Guide 2014 on the implementation of EU product rules.

Technical requirements for electrical drives equipment

  • Authors: Žáček, J., Ing. Karel Künzel, CSc.,
  • Publication: XXXIII. celostátní konference o elektrických pohonech. 2013. ISBN 978-80-02-02457-6.
  • Year: 2013
  • Department: Department of Electrotechnology
  • Annotation:
    An overview of EU technical legislation and its requirements applied to electrical drives equipment. European directives for low voltage safety, electromagnetic compatibility, ecodesign, restriction of the use of hazardous substances, and machinery. General knowledge of fundamental harmonised standards and specifications related to relevant directives. Prepared changes within the New Legislation Frame, proposals of recasted directives for electrical drives equipment.

Averaging for Control Programs of Active Filters

  • Authors: Brejcha, M., Hájek, J., Černek, P., Pígl, J., prof. Ing. Václav Papež, CSc., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Proceedings of the 13th International Scientific Conference EPE 2012. Brno: VUT v Brně, Fakulta elektrotechniky a komunikačních technologií, 2012. pp. 323-328. ISBN 978-80-214-4514-7.
  • Year: 2012
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with issues of calculating average value of instantaneous active power in control programs of active harmonic conditioners (active harmonic filters). Common methods based on infinite impulse response (IIR) digital filters are not optimal in some cases. The reason could be the computational and memory complexity. The article describes the cases of instabilities of the IIR filters, which leads to malfunction of control program of active filter. The CIC decimator is presented as suitable substitution of IIR filters.

Binding requirements for power appliance ecodesign (final part two)

  • Authors: Žáček, J., Ing. Karel Künzel, CSc.,
  • Publication: Elektro. 2011, 21(10), 80-82. ISSN 1210-0889.
  • Year: 2011
  • Department: Department of Electrotechnology
  • Annotation:
    Requirements for ecodesign of selected appliance groups. An overview of published Commission Regulations (EU).

Binding requirements for power appliance ecodesign (part 1)

  • Authors: Žáček, J., Ing. Karel Künzel, CSc.,
  • Publication: Elektro. 2011, 21(8-9), 48-50. ISSN 1210-0889.
  • Year: 2011
  • Department: Department of Electrotechnology
  • Annotation:
    Fundamental aspects for ecodesign, life cycle of a product. Legislation of requirements for power appliance ecodesign. Obligations of manufacturers when placing products on the European market.

EMC laboratory of power systems

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Aktuální otázky a vybrané problémy řízení elektrizační soustavy. Praha: EGÚ, 2011. pp. 1-12.
  • Year: 2011
  • Department: Department of Electrotechnology
  • Annotation:
    The article describes laborary, EMC test including technical standards. The practical experiences are introduced.

EMC of power line suplied equipments

  • Authors: Ing. Karel Künzel, CSc.,
  • Publication: Monitoring, měření a progresivní eleborace technologických dat v energetice. Praha: EGÚ, 2011. pp. 1-10. Cyklus E2011.
  • Year: 2011
  • Department: Department of Electrotechnology
  • Annotation:
    Paper deals with electromagnetic compatibility of equipments suplied from power line network. The process of assesment declaration is described. Next part deals with harmonized standards and with tests demanded by harmonized standards. The neharmonized tests are described too. Experiences from laboratory are presentet on the end.

Teaching in Electromagnetic Compatibility

  • Department: Department of Electrotechnology
  • Annotation:
    Proposal publication is focused on EMC branch. Except "classical" chapters it is interested in legislation and economical aspects of EMC, in designing and introducing electrical equipment into operation. Authors were deeply interested in new term "fixed installation", that is defined in new EU directives for EMC. Due to the accent on actual legislation process this publication is the only one in our country.

Development, reliability and safety of electrical power systems

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Elektrotechnologie 2009. Praha: České vysoké učení technické v Praze, 2009. ISBN 978-80-01-04379-0.
  • Year: 2009
  • Department: Department of Electrotechnology
  • Annotation:
    The reliability and safety of electrical power systems and the influence of disturbance emissions. The methods for reliability, functional safety and quality of electrical energy improovement.

Voltage source rectifier fed from the distorted power supply

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: XXXI. celostátní konference o elektrických pohonech. Praha: Česká elektrotechnická společnost, 2009. pp. 153-158. ISBN 978-80-02-02151-3.
  • Year: 2009
  • Department: Department of Electrotechnology
  • Annotation:
    Voltage source rectifier, one of the most widespread mains converters, shows at some cases surprising performance that sensitively respons to the mains voltage distortion. The paper describes and explains such effects and presents possible unfavourable reactions. The examples of measured results both on the experimental workplace and on real network are presented. The survey of tests declared in the European EMC standards complements the general view.

Power voltage sources with sinusoidal wave shape

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with power supplay for laborator purposes with sinusoidal wave shape of supply voltage. The sources work on power network frequency with minimum disturbances in wide frequency range. Such sources can be used for EMC measurement of harmonics, conducted emissions and other accurate measurements. The supressing of disturbance signals by filters is mentioned too.

High-frequency anti-parasitic filters

  • Authors: Žáček, J., Ing. Karel Künzel, CSc.,
  • Publication: Automatizace. 2007, 50(7-8), 493. ISSN 0005-125X.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with principles and structure of filters for RF disturbances suppression in electrical equipment and power lines. The filters are used for mitigation of disturbing emissions and immunity increase in order to EMC improvement and increase the function safety and reliability of operated equipment.

New EMC Demands on Fixed Installation of Electric Drives

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: XXX. celostátní konference o elektrických pohonech. Praha: Česká elektrotechnická společnost, 2007. pp. 167-172. ISBN 978-80-02-01921-3.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    The article deals with new aspects of fixed installations of electric drives from point of view new EMC EU directive. The possible structure of EMC plan and the role of designers, applications engineers and operators of electric drive systems.

Questions of EMC at University Teaching of Electric Power Engineering

  • Department: Department of Electrotechnology
  • Annotation:
    The paper explains problems of EMC education. The students safety and instruments safety during laboratory experimentation are discussed. The selected aspects of EMC education on department of electrotechnology at Faculty of Electrical Engineering CTU Prague are presented.

Surge Guards - Market Overview

  • Authors: Žáček, J., Ing. Karel Künzel, CSc.,
  • Publication: Automatizace. 2007, 50(7-8), 485-489. ISSN 0005-125X.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    The market overview presents products for EMC improvement. They are used in apparatus, equipment , power and data lines for transient overvoltages suppression. They increase the function safety and reliability of operated equipment.

Technological Aspects of Noise-suppressing Filter Design

  • Authors: Ing. Karel Künzel, CSc., prof. Ing. Václav Papež, CSc.,
  • Publication: PIERS 2007 Prague - Proceeding of Progress In Electromagnetics Research Symposium. Cambridge, MA: The Electromagnetics Academy, 2007. pp. 102-106. ISSN 1559-9450. ISBN 978-1-934142-02-8.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    The noise suppression is up to date problem of power electronic devices like power sources, power converters etc. Paper deals with suppression of conducted disturbances. Main topic is the filter design and it's assembling from real devices with theirs real characteristics. Filter topology and device wiring are very important too. Paper calls attention to selected questions and proposes their solution.

The Difficulties of Noise-suppressing Filter Design

  • Department: Department of Electrotechnology
  • Annotation:
    The article deals with miscellaneous aspects of noise-suppressing filter design and application, especially with posibility worsen or fully inhibit correct filter function.

Design of electromagnetically compatible power electrical systems

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Advanced Engineering Design AED 2006. Praha: České vysoké učení technické v Praze, 2006. ISBN 80-86059-44-8.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with problems of EMC requirements for fixed installation, the required documentation including so called EMC plan, simulations and testing. The material may serve as methodology for wide professional community.

EMC in Technical Practice I: Legislative Requirements

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with the important prepared change of European EMC Directive. It presents reasons and process of its origin as well as principal changes it brings.

EMC in technical practice II: Disturbing signals, their sources and propagation

  • Department: Department of Electrotechnology
  • Annotation:
    The article describes the diverse sources of electromagnetic disturbing signals and theirs classification from different points of view as well as ways of propagation of disturbing signals.

EMC in technical practice III: Low frequency noise suppression

  • Department: Department of Electrotechnology
  • Annotation:
    The article is focused on problems of low frequency disturbances represented mostly by so called power network disturbances. The appropriate choise of mittigation means is very important.

EMC in technical practice IV: High frequency noise suppression

  • Department: Department of Electrotechnology
  • Annotation:
    The paper is focused on the problems of conducted and radiated radiofrequency disturbances. The most common noise-suppressing tools are presented including theirs fundamental characteristics and application.

EMC in technical practice V: Earthing and cabling in fixed installations

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with the grounding and shielding of power and data cables, their space placing and suppression of disturbances induced in connecting wires.

EMC in technical practice VI: Basic measuring methods

  • Department: Department of Electrotechnology
  • Annotation:
    The paper presents the list of used and prepared tests for immunity assessment and meeting of emission limits. The basic standards specified the methods of tests and facilities are discussed.

Frequency converters and softstarters - market overview

  • Authors: Ing. Karel Künzel, CSc., Žáček, J., Cetl, T.
  • Publication: Automatizace. 2006, 2006(3), 207-214. ISSN 0005-125X.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with survey of czech market in field of frequency converters and softstarters. The product series are arranged to comprehensive table. Associated text amends and explain the table data including contemporary trends.

New European EMC Directive

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with the enforcement of the European EMC Directive 2004/108/EC in Czech legislation. The attention is focused namely on new defined fixed installations and the ways of the assessment and documentation of their conformity with the essential EMC requirements.

The measurement technique protection against external and internal disturbances

  • Authors: Ing. Karel Künzel, CSc.,
  • Publication: Elektrotechnologie '06. Plzeň: Západočeská univerzita v Plzni, 2006. pp. 186-189. ISBN 80-7043-476-7.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    The article is focused on using of expensive and sensitive measuring instruments in university laboratories. The resarch and education purposes are discused.

Electromagnetic Compatibility of Fixed Installations

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: International Conference Pelincec 2005. Warsaw University of Technology, 2005. pp. 1-6.
  • Year: 2005
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with the comparison of the original and new EMC Directives of EEC. It is focused particularly on the newly prescribed requirements for fixed installations.

Requirements For Line Current Harmonics Of Power Drive Systems

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: XXIX. celostátní konference o elektrických pohonech. Praha: Česká elektrotechnická společnost, 2005. pp. 56-61. ISBN 80-02-01733-1.
  • Year: 2005
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with the actual and prepared requirements on the limitations of power current harmonics for converter fed power drive systems. The real possibility of conformity achievement are verified by simulations.

Electrical Standards in Education

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: SYMEP 2004. Praha: CTU Publishing House, 2004. pp. 271-275. ISBN 80-01-03018-0.
  • Year: 2004
  • Department: Department of Electrotechnology
  • Annotation:
    The paper presents the significance and use of technical standards in education process and in elaboration of semestral projects and diploma thesis.

Power Engineering Education and RF Properties of Power Devices and Converters

  • Department: Department of Electrotechnology
  • Annotation:
    The article deals with some problems related to application of contemporary power semiconductor devices.

RF Meesurements in Power Engineering

Electromagnetic Compatibility of SMPS

Laboratory of EMC at Department of Electrotechnology FEE CTU

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Diagnostika a řízení jakosti v elektrotechnice. Praha: Ediční středisko ČVUT, 2003. pp. 73-78. ISBN 80-01-02785-6.
  • Year: 2003
  • Department: Department of Electrotechnology
  • Annotation:
    The paper presents the equipment of electromagnetic compatibility laboratory and the scope of realised tests according to harmonised standards

Measurement of SMPS RF Conducted Emissions

Measurement of SMPS RF Conducted Emissions

Measurement System of RF Interferencies a Power Equipments

Multistandard Serial Communication Analyzer

  • Authors: Ing. Karel Künzel, CSc., Maršík, T.
  • Publication: Applied Electronics. Plzeň: ZČU Plzeň, 2003. pp. 133-135. ISBN 80-7082-951-6.
  • Year: 2003
  • Department: Department of Electrotechnology
  • Annotation:
    This article describes a multistandard serial communication analyzer which was made and tested at the Department of Electrotechnology, FEE, CTU. This device can be directly used for the standards TTL, RS232, and RS485/422, and the construction enables to extend the analyzer easily by other standards. Beside observing a full duplex serial communication, this device is also able to transmit serial data. This article is focused mainly on the hardware implementation of the analyzer.

Power supply - The market overview

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Automatizace. 2003, 46(3), 194-201. ISSN 0005-125X.
  • Year: 2003
  • Department: Department of Electrotechnology
  • Annotation:
    The paper is focused on the market overview of the power supplies. The basic parameters are presented. The paper contains the table and the explaining text.

Some Problems of EMC of Electric Drives

The Electromagnetic Compatibility of SMPS

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with assurement, measurement and assessment of electromagnetic compatibility of switching mode power supplies.

The problems of RF conducted emissions measurement

Where starts and where ends power electrical engineering

Effect of Network Qualitz on Parameters of Electrical Energy Consumed bz Switch Mode Power Sources

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Elektroenergetika 2002. Praha: České vysoké učení technické v Praze, 2002. pp. 97-100. ISBN 80-01-02614-0.
  • Year: 2002

High Frequency Parameters of Power Cables

Tehe future of European EMC Directive

  • Authors: Ing. Karel Künzel, CSc.,
  • Publication: Sborník ERU'2002. Brno: AV studio fy ELCOM, 2002. pp. 1-7.
  • Year: 2002

The EMC Laboratory and its use in Power Electrical Engineering Education

  • Authors: Žáček, J., Ing. Karel Künzel, CSc.,
  • Publication: 19. Mezinárodní symposium učitelů elektrických pohonů SYMEP 2002. Liberec: Technická univerzita, 2002. pp. 20-24. ISBN 80-7083-612-1.
  • Year: 2002

Elektromagnetické vyzařování laboratorních přístrojů se spínanými zdroji

The Diagnostic of Power Convertor Output Filters

The Overvoltage Suppression in A.C. Converter Drives

The Overvoltage Suppression on the long Cable with Matching Circuit

EMC filters and their application

EMC Laboratory of Power Systems and its Application for Educational Purposes

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: EPE-PEMC 2000. Košice: TU Košice, 2000. pp. 7-200-7-203. ISBN 80-88922-20-8.
  • Year: 2000

RF Characteristics of Power Cables

Spectral Measurement on the System Frequency Converter-Cable-Induction Motor

The Education EMC Laboratory of Power Systems

  • Authors: Žáček, J., Ing. Karel Künzel, CSc.,
  • Publication: EMC, York 2000. York: York EMC Services, 2000. pp. 1-4. ISBN 1-902009-02-9.
  • Year: 2000

Lowpower Sources

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Automatizace. 1999, 42(3), 187-188. ISSN 0005-125X.
  • Year: 1999

Market overview - Industrial Chargers and Sources for Electrochemistry

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Automatizace. 1999, 42(12), 896-900. ISSN 0005-125X.
  • Year: 1999

Propagation of the Voltage Surge in Power Cables

The Voltage Stress of Cage Induction Motor Fed from Invertor

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Electrical Drives and Power Electronics. Košice: TU Košice, 1999. pp. 334-337. ISBN 80-88922-06-2.
  • Year: 1999

View of Markets

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Automatizace. 1999, 42(7), 509-515. ISSN 0005-125X.
  • Year: 1999

Fair Informatic and Foul Technology

  • Authors: Urbánek, J., Ing. Karel Künzel, CSc.,
  • Publication: Elektrotechnologie 98. Plzeň: Západočeská universita, 1998. pp. 79-81. ISBN 80-7082-433-6.
  • Year: 1998

Harmonic Current Emission of Equipment with a Special Wave Shape

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Power Electronics and Motion Conference '98. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 1998. pp. 37-40. ISBN 80-01-01832-6.
  • Year: 1998

The simulation and measurement of "class D" equipment in acordance with EN -

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Sborník ERU'1998. Brno: AV studio fy ELCOM, 1998. pp. 1-11.
  • Year: 1998

Computer Techniques on Department of Electrotechnology

  • Authors: Ing. Karel Künzel, CSc.,
  • Publication: Materiály a výrobné procesy v elektrotechnike. Bratislava: STU v Bratislave, 1997. pp. 90-92. ISBN 80-227-0991-3.
  • Year: 1997

Market Overview - Frequency Converters for Drives with Asynchronous Motors

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Automatizace. 1997, 40(2), 92-109. ISSN 0005-125X.
  • Year: 1997

The Recent Development Trends of Frequency Converters for ac Drives

  • Authors: Ing. Karel Künzel, CSc., Cetl, T., Žáček, J.
  • Publication: XXV. celostátní konference o elektrických pohonech. Praha: ČSVTS, 1997. pp. 200-205. ISBN 80-02-01167-8.
  • Year: 1997

Transistorized Rectifiers

  • Authors: Ing. Karel Künzel, CSc., Seborský, S., Žáček, J.
  • Publication: Workshop 97. Praha: České vysoké učení technické v Praze, 1997, pp. 841-842.
  • Year: 1997

Control of PWM Rectifiers

  • Authors: Ing. Karel Künzel, CSc., Lettl, J., Seborský, S., Žáček, J.
  • Publication: Proceedings of Electrical Drives and Power Electronics '96. Košice: TU Košice, 1996. pp. 121-126. ISBN 80-967249-3-2.
  • Year: 1996

Market survey-uninterruptible power sources

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Automatizace. 1996, 39(10), 517-540. ISSN 0005-125X.
  • Year: 1996

Modern Tools of Production Systems Analysis Applied in Education

  • Authors: Ing. Karel Künzel, CSc., Ing. Martin Molhanec, CSc., Žáček, J.
  • Publication: Proceedings of the 19th International Spring Seminar on Electronics Technology ISSE 96. Budapest: Technical University, 1996. pp. 227-231. ISBN 963-420-505-4.
  • Year: 1996

PWM Methods and Their Demands on IGBT Dynamics

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Proceedings of the 3rd International Seminar on Power Semiconductors ISPS 96. Praha: České vysoké učení technické v Praze, 1996. pp. 217-222.
  • Year: 1996

PWM Rectifiers

  • Authors: Ing. Karel Künzel, CSc., Seborský, S., Žáček, J.
  • Publication: Workshop 96. Praha: České vysoké učení technické v Praze, 1996, pp. 655-656.
  • Year: 1996

Controls of PWM Rectifier

  • Authors: Klečka, M., Ing. Karel Künzel, CSc.,
  • Publication: Sborník XXIV. celostátní konference o elektrických pohonech. Plzeň: Dům techniky, 1995. pp. 167-172.
  • Year: 1995

Hardware for Energy Conversion from Alternative Sources

  • Authors: Cetl, T., Klečka, M., Ing. Karel Künzel, CSc., Seborský, S., Žáček, J.
  • Publication: Workshop 95. Praha: České vysoké učení technické v Praze, 1995, pp. 525-526.
  • Year: 1995

SIMULINK How MATLAB Simulates the Behavioue of Dynamic Systems

Uniterruptible Power Sources

  • Authors: Cetl, T., Ing. Karel Künzel, CSc., Seborský, S., Žáček, J.
  • Publication: Elektronika. 1994, 44(4), 29-43. ISSN 0862-4607.
  • Year: 1994

Modelling of Power Systems with Semiconductor Converters

  • Authors: Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Multimedia and Computer Tools: The Future for Engineering. Fourth Annual Conference. Praha: České vysoké učení technické v Praze, 1993, pp. 220-224.
  • Year: 1993

Responsible person Ing. Mgr. Radovan Suk