Michal Krbal

Operating parameters of luminaires for phytotron

The parameters of luminaires for the phytotron and growth chambers have some characteristics different from conventional luminaires. Example could be the different requirements for spectral distribution, thermal management and requirements for irradiation of plants. This paper deals with the complex description of these requirements on luminaires and they properties, supported by its own laboratory measurements.

Comparison of light sources for household use due circadian effect

The aim of the paper is to compare of light sources for household use. These sources are compared due to content of blue light in their spectrum. Classical bulb, halogen bulb, linear fluorescent lamp and LED retrofits were used for spectrum measurement. It was used fluorescent lamp and LEDs with various colour temperature.

Laboratory high voltage capacitor with low PD level and low dissipation factor

High voltage capacitors are widely used in middle and high voltage laboratories and testing rooms. Capacitors are used for measurement of voltage in the form of voltage dividers. Injection and blocking capacitors are placed in the galvanic systems of partial discharges. And high voltage capacitors are also used in the high voltage as the part of laboratory bridge circuits. Common characteristics of these capacitors are the stability of parameters in time and voltage, low value of PD level. And usage as the capacitor with low value of dissipation factor (tan delta) for bridges. This paper is focused on the description of the parameters of these capacitors, their implementation and the function verification.

Visual angle in photobiological safety

This paper deals with theme of measuring of photobiological safety. For evaluating of photobiological safety is important determination of visual angle of source. Paper is describing effect of visual angle change on measured data. Visual angle was changed by changing of measuring distance and by changing of field stop diameter. All measurement was realized on double monochromator spectroradiometer.

Ecodesign of light sources

The aim of this paper is to determine the amount of materials which are used in the light sources construction. Another aim of this paper is to identify environmental demands in the production and disposal of light sources on the basis of the material composition.

Use of photometry in the field of high voltage

Laboratory testing of high voltage tested objects often leads to creation of discharges. Discharges are generated by breakdowns or flashovers outer insulation of the tested objects. These discharges generate emission in the IR, UV and also in the spectrum of light. The spectrum and intensity of radiation is dependent on the duration and level of passing current discharge. The shape, density and the spectrum of the discharge are also to some extent affected by the chemical composition of the gas surroundings, the electrode materials and the atmospheric pressure. The parameters of discharges are usually in HV laboratories specified by the measured time course of voltage and current passing through the discharge. An alternative is using of the analytical tools of lighting laboratory. Timing can be determined by using a fast photodiode. The chemical composition of the gas atmosphere and the electrode material affect the measured spectrum of light and UV. The average measured brightness value is dependent on the passing current of discharge and ambient gas pressure. The content of the article is focused on the application of some instruments from the filed of photometry to the high voltage measurement. This opens up new possibilities for the combination of these two disciplines and finding new possibilities of application.

Design and construction solution of laboratory Tesla coil

Tesla coil is high-voltage high-frequency testing source used in laboratories and testing departments of MV and HV. This paper deals with the design, implementation and measured output operational parameters of the Tesla coil, which is located in the High voltage laboratory in Brno University of Technology.

Growth chamber illumination with a special luminaire

Article describes the design of lighting in growth chamber with low energy consumption. For this purpose we created a special luminaire that allows during different phases of plant life, regulate the spectrum of emitted energy and thereby effectively utilize light without wasting electricity. It is also important light intensity for proper growth of plants, respectively incident radiation. The paper discusses the directional characteristics of the luminaire and its spectral distribution which are an important part of the input data for the design lighting.

Electrical parameters of water at lightning impulse

This paper deals with the description of the behavior of water at lightning impulses. The electric potential distribution in water at lightning impulses is simulated for the calculation of the safe distance. There are not hazardous conditions to human body at distances greater than the safe distance. The examples are swimming pools or water where people are bathing. In these simulations is considered a constant conductivity of the water at impulse current of lightning. But conductivity is not constant value, it change over time and with the instantaneous value of the current passing through. So the main benefit of this article is a description of change in the behavior of the water conductivity.

Cherenkov glow analysis by Luminance Distribution Processing

Nowadays there are great operational challenges placed on nuclear power plants. It is not only the physical security of the nuclear power plant but it must be guaranteed even against diversion of nuclear fuel and proliferation risk. The spent fuel inspections are the one way to ensuring nonproliferation risk. Inspections are carried out to check the physical presence of fuel assembly. But it also is useful to have tools to detecting fuel assembly or fuel pin manipulation. A typical example is partial defect detection. It was developed several devices for inspections of spent fuel using a Cherenkov glow analysis. These include Scientific Cherenkov viewing device or viewing device with CCD cameras. These devices evaluated Cherenkov glow in the UV spectrum. This article deals with the detection Cherenkov glow in the visible spectrum. This is a new way of using a top LumiDISP measuring system, which was developed for the analysis of the luminance. Spent fuel pool was analyzed by the LumiDISP measuring system and results were compared with fuel assemblys information.