EMI Pre-Compliance Measurements Reveal Sources of Interference

The chapter focuses on the electromagnetic compatibility of a prototype of electrical equipment such as street lighting with various LED controllers, LED information boards, and audio equipment. The requirements for the harmonic content of the input currents of the conducted emission power lines are used as a basis for the analysis of compliance with the EMC standards. The results obtained from the experiments indicated that some commercially produced voltage drivers are not compatible with the requirements for the harmonic current content of the input line. The problem is caused by two factors: a bad design by the manufacturer or the wrong LED driver design concerning the rated load. EMI radiation measurements indicate the need to precisely design all functional blocks placed on a PCB with suitable grounding and shielding techniques. This chapter is intended for engineers and researchers working in the development of electrical equipment as well as the general public interested in EMC issues

Daytime Lighting Assessment in Textile Factories Using Connected Windows in Slovakia: A Case Study

This paper highlights the problems that are associated with daylight use in industrial facilities. In a case study of a multi-story textile factory, we report how to evaluate daylight (as part of integral light) in the production halls marked F and G. This study follows the article in the Buildings journal, where Hall E was evaluated (unilateral daylight). These two additional halls have large areas that are 54 × 54 m and are more than five meters high. The daylight is only on the side through the attached windows in envelope structures in the vertical position on the hall. In this paper, we want to present two case studies of these two production halls in a textile factory in the eastern part of Slovakia. These are halls that are illuminated by daylight from two sides through exterior peripheral walls that are against or next to each other. The results of the case studies can be applied in similar production halls illuminated by a “double-sided” (bilateral) daylight system. This means that they are illuminated by natural illumination through windows on two sides in a vertical position. Such a situation is typical for multi-storied industrial buildings. The proposed approximate calculation method for the daylight factor can be used to predict the daylight in similar spaces in other similar buildings

Sensing Method Using Multiple Quantities for Diagnostic of Insulators in Different Ambient Conditions

Insulators are one of the many components responsible for the reliability of electricity supply as part of transmission and distribution lines. Failure of the insulator can cause considerable economic problems that are much greater than the insulator cost. When the failure occurs on the transmission line, a large area can be without electricity supply or other transmission lines will be overloaded. Because of the consequences of the insulator’s failure, diagnostics of the insulator plays a significant role in the reliability of the power supply. Basic diagnostic methods require experienced personnel, and inspection requires moving in the field. New diagnostic methods require online measurement if it is possible. Diagnostic by measuring the leakage current flowing on the surface of the insulator is well known. However, many other quantities can be used as a good tool for diagnostics of insulators. We present in this article results obtained on the investigated porcelain insulators that are one of the most used insulation materials for housing the insulator’s core. Leakage current, dielectric loss factor, capacity, and electric charge are used as diagnostic quantities to investigate porcelain insulators in different pollution conditions and different ambient relative humidity. Pollution and humidity are the main factors that decrease the insulator´s electric strength and reliability

Influence of Light Reflection from the Wall and Ceiling Due to Color Changes in the Indoor Environment of the Selected Hall

The main goal of this paper is to evaluate the effect of color changes on the interior surfaces of a selected hall on the level of daylight, represented by the DF factor. A single-story hall was chosen as the reference building, in which daylight falls through the side windows and a skylight at roof level. Measurement of the level of daylight in the real state of the building (in situ) was carried out. The measurement took place when the external boundary conditions of the measurement were met (external state of the sky). A survey was conducted among users, in which they considered the visual perception of the environment and what colors would be suitable for the walls, ceiling, and floor in the working environment of the hall. The evaluation of the respondents who considered the color of the floor was interesting, and several agreed that the floor should be brown. After debugging the model for the simulation based on the actual state of the measurement, simulation calculations were performed with selected surface colors in the interior of the hall. Computational simulations were performed for changing calculation boundary conditions. Daylight Factors (DF) (%) were evaluated, namely minimum, maximum, and average DF values for 15 selected simulations. The calculations were performed in the RADIANCE simulation program. Simulations included the change in the surface color of the simulated wall and the current ceiling surface color, the color of the simulated ceiling surface and the current wall surface color, and the color of the simulated wall and ceiling at the same time. The floor color did not change during the evaluation; it was considered brown. Based on the evaluation of AHP, evaluations of the significance and comparability of colored areas were performed. The value of the average DF was chosen as the most important, the less significant minimum DF value was chosen, and the maximum DF value was considered in the last place. The results show that white, gray, green, or yellow walls, white ceiling, and brown floor were rated as the most suitable for the interior surfaces in the considered hall

Sensing Method Using Dielectric Loss Factor to Evaluate Surface Conditions on Polluted Porcelain Insulator

Insulator diagnostics is still a topical issue. No one has yet found out how to accurately determine the condition of all insulators and decide when replacement or maintenance is required. Insulators are one of the main components of a transmission and distribution system and must withstand high voltages in all weather conditions. Moisture and dirt are the main factors influencing the insulating properties of insulators. This article deals with the effect of pollution on a porcelain insulator. An Omicron MI 600 measuring system monitors the changes in the dielectric loss factor and leakage current in a wide frequency range (10 Hz to 1 kHz) to evaluate the contamination level. We applied three high voltage levels (5 kV, 7.5 kV, and 10 kV) to the porcelain insulator to monitor changes in the mentioned quantities with various frequencies. The measurement results confirmed the usability of the dielectric loss factor and leakage current for the diagnosis of insulator pollution. The dielectric loss factor showed more promising results than the leakage current

Frequency-Dependent Dielectric Spectroscopy of Insulating Nanofluids Based on GTL Oil during Accelerated Thermal Aging

Improving the dielectric properties of liquid-insulating materials is a current problem in research into the insulation system of a power transformer. Modern optimization of insulating liquids involves the potential use of unique synthetic esters enriched with nanoparticles. This study presents the results of the dielectric response of liquefied gas-based (GTL) insulating liquids during accelerated thermal aging. The dielectric relaxation spectroscopy method was used in the frequency domain to point out power losses as an imaginary part of a complex electric modulus. The relaxation spectra express the validity of applying this complex dielectric parameter. The polarization processes of the base oil alternately change position in the low-frequency band during thermal aging. Fullerene nanofluid undergoes three phases of dielectric loss changes during thermal aging. In the case of magnetic nanofluid, the effect of electric double-layer polarization disappeared after 500 h of thermal aging. It was found that with the gradual increase in the thermal aging time, there is no gradual increase in the dielectric losses investigated in the measured frequency spectrum. This study shows that the concentration of the two types of nanoparticles independently causes a different dielectric response to an applied AC electric field in the GTL base fluid

Dielectric relaxation response of electrical insulating liquids under different natures of thermal stress

This study focuses on the dielectric relaxation response of insulating liquids based on mineral oil and synthetic ester in a thermal field.The research also offers the dielectric relaxation response of the magnetic nanofluid based on the investigated synthetic ester. The reason for investigating the synthetic ester-based nanofluid is that the temperature characteristics of the mineral oil-based magnetic nanofluid have already been investigated in several studies. Nanofluid based on synthetic ester is not sufficiently explored in this regard. The behavior of insulating liquids in the thermal field is divided into two parts. The first one points to the effect of temperature on the dielectric properties of the insulating liquids in the range from 293.15 K to 363.15 K. The insulating liquids show relaxation processes in the investigated frequency spectrum (1 mHz–3 kHz), which are dependent on temperature. The logarithm of the relaxation frequency decreases linearly with decreasing temperature according to Arrhenius' law. Mineral oil has the highest value of activation energy. In the second part, the results are focused on the influence of the rate of temperature increase on the dielectric parameters and moisture content of the investigated fluids. A slower increase in temperature causes an increase in polarization losses and a reduction in the distribution of relaxation times. In the case of base oils, also a reduction in activation energy. The change in the heating rate of the investigated liquids does not affect their moisture. Changes in dielectric parameters are not caused by changes in the moisture of insulating liquids, but by thermal aging

Dielectric Properties of Electrical Insulating Liquids for High Voltage Electric Devices in a Time-Varying Electric Field

The motivation to improve components in electric power equipment brings new proposals from world-renowned scientists to strengthen them in operation. An essential part of every electric power equipment is its insulation system, which must have the best possible parameters. The current problem with mineral oil replacement is investigating and testing other alternative electrical insulating liquids. In this paper, we present a comparison of mineral and hydrocarbon oil (liquefied gas) in terms of conductivity and relaxation mechanisms in the complex plane of the Cole-Cole diagram and dielectric losses. We perform the comparison using the method of dielectric relaxation spectroscopy in the frequency domain at different intensities of the time-varying electric field 0.5 kV/m, 5 kV/m, and 50 kV/m. With the increasing intensity of the time-varying electric field, there is a better approximation of the Debye behavior in all captured polarization processes of the investigated oils. By comparing the distribution of relaxation times, mineral oil shows closer characteristics to Debye relaxation. From the point of view of dielectric losses at the main frequency, hydrocarbon oil achieves better dielectric properties at all applied intensities of the time-varying electric field, which is very important for practical use