Use Of LED Lamps Research Articles

Myopia and Environmental Risk Factors: A Comprehensive Study

Background: The global rise in the prevalence of myopia calls for evidence-based strategies to be devised to reduce the incidence and delay the progression of Myopia. The aim is to determine the relationship between myopia incidence and some environmental factors. Methods: A cross-section observational study was conducted at Alzahraa Teaching Hospital from May 2023 to December 2023. Primary school students of both genders. All students were enrolled in the study after an agreement with their parents/guards. Data was collected using a pre-constructed data collection sheet (questionnaire) including three sections, the first section was sent to the families to fill and sign the consent for participation and provide the required data including the demographic variables, family history and medical history of the students, time outdoors, prolonged near work/increased study hours, high BMI, use of LED lamps for homework, less sleeping hours, low Vitamin D levels, less participation in sports and low socioeconomic status. The second part included the general examination of the students, school grades and education performance (assessed according to the student school Cards). The third section involved the ophthalmological examination, visual acuity and ophthalmoscopic examination. Results: A total of 100 students were enrolled in this study, they were equally distributed according to gender, 50 boys and 50 girls. The age of students ranged between 6 and 12 years. Only 12 students had positive past medical and surgical history. A family history of myopia was reported in 20% of the studied group, 20 children were wearing spectacles and a history of past eye complaints was reported in 9 (9%) of children. The refractive errors were 45% hypermetropia, 39% myopia and 16% astigmatism. Abnormal visual acuity was detected in 35%. Myopia was significantly higher in children with family history (p=0.007). A statistically significant relationship was found between large time outdoors and myopia (OR=4.52, p=0.02). A statistically significant relationship was found between prolonged near-work/increased study hours and myopia (OR=4.52, p=0.02). A statistically significant relationship was found between using LED lamps for homework and myopia (OR=10.33, p<0.0001). A statistically significant relationship was found between fewer sleeping hours and myopia (OR=7.5, p<0.0001). Conclusion: Prevention of the onset of myopia and delay in the progression of myopia can be altered by modifying the contributing environmental risk factors. Raise outdoor time with adequate sunlight exposure, rural environment, less duration of near work, use of incandescent lamp and normal sleeping rhythms with adequate regular sleeping hours can prevent the onset and progression of myopia. Myopia is associated with high BMI, watching television and playing digital devices. High socioeconomic status associated with more indoor activity, increased academic pressure, sedentary lifestyle contribute to the prevalence of myopia.

Status of Lighting Technology Application in Indonesia

In 2019, Indonesia’s electricity consumption exceeded 278 TWH, or about 1.08 MWh/capita. This value shows a considerable increase in electricity consumption which has doubled in just a decade. Previous studies have shown that the proportion of electricity consumption used for lighting needs is correlated to the country’s GDP. This is generally around 20 to 50% of electricity production but can go up to 86% in the case of Tanzania. Indonesia is the 4th country in the world in terms of population and its lighting market as well as its lighting-related energy consumption has a strong impact on several levels: societal, environmental but also economic and energy. Having a knowledge of the lamps used by the Indonesian people is therefore particularly interesting and important, in particular in the context which presents a great societal diversity but also in a context of energy saving. Indonesia is an archipelagic country made up of 5 large islands and over 17,000 small islands with widely varying levels of population density. This island geography leads Indonesia to face challenges in the distribution and production of electrical energy, which affects the use of lamps in various types of regions. The overview of this study was done by collecting data from various sources, especially BPS (Biro Pusat Statistik/Statistic Center Bureau of Indonesia), CLASP (an NGO for clean energy), the Ministry of Energy and Mineral Resources of Indonesia (ESDM), PLN (Indonesian Electrical Company), etc. The data obtained from these sources provides several descriptions of general lighting conditions in Indonesia viewed from several angles, such as growth of lamp market, use of lamp types, percentage of use of lamps with energy saving (ESL), etc. Considering that Indonesia has various regional characteristics, in this study, the survey of a total of 394 respondents was conducted on the use of lamps by creating regional categories based on electrical conditions, power consumption, and electricity per capita, among others. The categories of areas observed fall into 5 types based on their population and geography: large cities, small towns, rural/village areas, islands and remote areas. The results of compiling data from these various sources show that the types of lamps used by Indonesians follow the lighting trend in the world. The use of LED lamps has a utilization percentage of around 52%, much higher than other types of lamps such as CFL, fluorescent or incandescent. Based on the survey conducted, it is known that the widely used LED power is between 1 and 10 watts with a usage time of 8 to 12 h per day. In the next few years, it is estimated that the use of LEDs in Indonesia will increase as the government has prepared various regulations and policies related to energy saving, one of which relates to lighting.

Применение освещения различного спектрального диапазона при клональном микроразмножении лесных ягодных растений

Creation of plantations of the most popular species of forest berry plants with high nutritional and medicinal value is advisable in connection with the reduction of such natural resources and the increased demand for berry products, as well as for the biological reclamation of depleted peat deposits. The paper shows the research results of clonal micropropagation of forest berry plants (cranberry, American cranberry, half-high blueberry, Arctic bramble, lingonberry, Kamchatka bilberry) of promising cultivars and forms using various types of lighting (white LED lamps, LED lamps with a combination of white, red and blue spectra, as well as white fluorescent lamps). Plants were cultivated using WPM and MS nutrient media with the addition of cytokinins 2-iP and 6-BAP in various concentrations. The largest number (3.3–16.9 pcs) and the maximum total length (13.8–251.1 cm) of microshoots of cranberry (Dar Kostromy cultivar, hybrid form 1-15-635), American cranberry (Ben Lear cultivar, hybrid form 1-23-3), Arctic bramble (Anna cultivar, hybrid form K-1), lingonberry (Kostromskaya rozovaya and Rubin cultivars) and Kamchatka bilberry (Sakhalinskaya and Kurilskaya forms) were observed under lighting by LED lamps with a combination of white, red and blue spectra at the “proper micropropagation” stage. The formation of the largest number (13.1 pcs) and the maximum length (98.7 cm) of microshoots of half-high blueberry (Northblue cultivar, hybrid form 23-1-11) was observed under lighting by white fluorescent lamps. There were no significant differences in biometric parameters of plants under different types of lighting depending on cultivars and forms. The use of LED lamps with a combination of white, red and blue spectra has a significant effect on the formation of microshoots of forest berry plants during clonal micropropagation. For citation: Makarov S.S., Upadyshev M.T., Kuznetsova I.B., Zaushintsena A.V., Kulikova E.I., Surina E.A. The Use of Lighting of Various Spectral Ranges for Clonal Micropropagation of Forest Berry Plants. Lesnoy Zhurnal = Russian Forestry Journal, 2022, no. 6, pp. 82–93. (In Russ.). https://doi.org/10.37482/0536-1036-2022-6-82-93

Influence of light parameters on the cultivation of oil radish microgreens

Relevance. The technology of growing microgreens of individual vegetables had been previously studied in literature. However, the issues of the influence of light parameters on the cultivation of oil radish microgreens have not been studied enough.Methods. The model crop was oil radish (Raphanus sativus L. var. oleifera Metzg., variety Tambovchanka). Water was used as a substrate. With the use of LED lamps in the cultivation of oil radish microgreens, 4 series of experiments were carried out in March and October. All experiments were carried out in 4 replications. Seed weight — 5g per container with an area of 144 cm2. Weight of 1000 seeds — 14 g, seed germination — 96%. The average daily temperature for growing oilradish was 25 °C. Phytolamps of the laboratory "Intellect" ( Tula) include 72 pairs of LEDs in 2 versions: 1) 3 red, 1 blue (54 pairs of red, 18 pairs of blue); 2) 7 red, 1 blue (63 pairs of red, 9 pairs of blue). Phytolamps were turned on for 12 hours. The average level of illumination is 2700–2800 lux, the level of PAR is 42 µmol/(m2·s).Results. In spring, with an increase in the length of daylight hours, the indicators of the number and mass of seedlings of oil radish microgreens increase. In autumn, the number and weight of seedlings grown in daylight (with and without additional lighting by phytolamps) is affected by the number of sunny days. Additional lighting with phytolamps increases the mass of seedlings if the values of the parameters of the leading environmental factors are in the optimum zone. The ratio of red and blue LEDs 3:1 (54 pairs of red LEDs and 18 pairs of blue LEDs) was optimal for the development oil radish seedlings in spring and autumn. Additional lighting with phytolamps of 7:1 ratio practically did not affect the growth of seedlings in both terms of the experiment in 2020. This is due to the fact that in the early stages of development plants require more blue light.

EGG PRODUCTIVITY OF HENS DEPENDING ON ARTIFICIAL LIGHTING CONDITIONS PREMISES IN THE AREA OF THEIR KEEPING

Light is one of the technological stimuli affecting the physiological processes and behavioral reactions of hens. Enterprises producing edible eggs on an industrial basis keep laying hens mainly in windowless poultry houses, which are illuminated by various sources of artificial light. At the same time, the intensity of lighting and the duration of the daylight hours control their productivity. Recently, another factor affecting the preservation of laying hens was discovered. Therefore, the purpose of this study was to determine the efficiency of the production of edible eggs under the influence of the light stimulus on the body of hens caused by keeping them in rooms, the lighting of which is carried out by LED lamps with different light wavelengths. For this purpose, in the conditions of a modern complex for the production of edible eggs, 4 groups of hens were formed, each of which was kept in a separate poultry house-similar in terms of area and cage equipment (12-tier cage batteries of traditional designs). In particular, hens of the 1st group (control) were kept using LED lamps with a light wavelength of ~460 nm, the 2nd group ~600 nm, the 3rd group ~630 nm and the 4th group ~650 nm. It was found that the use of LED lamps with a light wavelength of ~650 nm to illuminate poultry houses during the keeping of egg-cross hens in cages of 12-tier batteries of traditional designs ensures the production of an additional 2.9-15.1 million eggs in 34 weeks of the productive period costing UAH 1.7-39.3 million, than LED lamps with a peak light wavelength of ~460, ~600 and ~630 nm. With the use of LED lamps with a light wavelength of ~650 nm, the preservation of laying hens was 95.5%, i.e. by 0.7-10.2% it exceeded the level achieved with other versions of them with a wavelength of world wavelength (~460-630 nm). At the same time, the cost of production of edible eggs amounted to UAH 1.47/eggs, that is, it was lower by 3.4-17.0%, and the level of profitability was 43.3% (it was higher by 1.7-9.5%).

The impact of off-grid solar home systems in Kenya on energy consumption and expenditures

This paper assesses the impact of solar home systems (SHS) on energy consumption and energy-related expenditures among Kenyan households. Based on a pipeline comparison approach of more than a thousand households, we find that access to a SHS leads to a net increase of 24 to 36 min in daily lighting use due to a 3 h increase in the use of LED lamps, accompanied by a reduction in the use of “dirty” lamps. We also find a one litre reduction in the monthly use of kerosene for lighting. These changes in energy use along with a decline in the cost of charging mobile phones leads to a reduction in overall monthly expenditure of KSh 193 (about EUR 1.60). For the most popular SHS, these economic effects translate into a payback period of about six years. In addition to the economic benefits, we find small positive environmental effects, increased satisfaction from better quality lighting and an increase in time spent watching TV. Setting the costs against the combined benefits of SHS suggests a positive payoff for this particular off-grid electricity option and a viable way forward in providing off-grid energy solutions with a wide range of functionalities in developing countries.

A comparative study of photo-Fenton process assisted by natural sunlight, UV-A, or visible LED light irradiation for degradation of real textile wastewater: factorial designs, kinetics, cost assessment, and phytotoxicity studies

The present work aims to evaluate the treatment of the effluent from the textile industry via advanced oxidative processes of photo-Fenton assisted by different sources (natural sunlight, UV-A or visible LED lamps). To identify the best operating conditions, a factorial design was carried out for each process. It was observed that after the optimization of the processes, chemical oxygen demand (COD) removals greater than 88% were achieved. In addition, it was observed that the use of the LED lamp required lower reagent concentrations compared to solar and UV-A sources. A kinetic study was carried out under the best conditions obtained and it was observed that the sources showed rapid evolution, reaching a COD removal equilibrium with 30 min of reaction. Reagent monitoring was also carried out, and it was observed that they were not limiting to the reaction. Phytotoxicity analysis was also satisfactory since the treated effluents allowed a higher relative growth and germination index of the cucumber roots compared to the raw effluent. Finally, the cost analysis indicated that the use of LED lamps resulted in a reduction in electrical consumption compared to the UV-A lamp, as well as a reduction in the cost of reagents due to the lower concentration of reagents required compared to processes assisted by natural sunlight and UV-A.

Bien éclairer les tests de vision des couleurs, la lampe TRUE COLOR LED : une innovation dans ce domaine

Given the latest trend in light sources, and in particular, the widespread use of LED lamps, we began to rethink the old lighting standards for colour vision testing. We (J.Leid) therefore conceived a new, easy to use, calibrated lamp with a specific ergonomic design, emitting light with a spectrum close to that of the standard D65, and perfectly adapted to pigmentary colour vision tests. A prototype conforming to a strict set of specifications in terms of quality and quantity of light, as well as ergonomics, was tested against a Macbeth lamp and fluorescent lighting, on controls and patients with congenital and acquired dyschromatopsia. Tests performed using our new lighting reveal, at a minimum, the same types of dyschromatopsia as the ones found with the old devices, and, in some cases, led to a more precise diagnosis, which we confirmed using an anomaloscope. These results demonstrate that an appropriate LED lamp permits perfect colour vision testing and appears superior to prior technology. The objective of the True Color LED Lamp is to offer practitioners a modern, energy-efficient, maintenance-free, compact, effective technological tool with specific ergonomics and a colour spectrum that provides optimal lighting for pigmentary colour vision testing, coupled with a double level illumination, which constitutes a favourable replacement for older devices which are no longer available or insufficiently calibrated.

COMPARATIVE ANALYSIS OF COMPACT FLUORESCENT LAMPS VERSUS LED LAMPS: AN ECONOMY FACTOR

The general objective of this article was to promote through bibliographic studies the two types of lamps, in addition to the comparative analysis of compact fluorescent lamps versus LED lamps: an economy factor. The specific objectives were: - to explain the conceptual precepts on: lighting engineering, definitions, characteristics, invention, operation, defect, quality and the environments used and the NBRs regulations; - address the economic impact generated by the choice of LED lamps and compact fluorescent lamps; - emphasize on an economic feasibility study on the use of LED lamps and compact fluorescent lamps. The justification of the study is related, in the promotion regarding the use of LED lamps and compact fluorescents, in the factor that generates savings. Since the areas related to artificial lighting are responsible for a significant portion of energy demand, both on a large scale - such as lighting for public roads or industrial buildings - and on smaller scales - in commercial and residential buildings. Therefore, its promotion is crucial in the context of economic viability. The lamps provide the luminous energy, through which a better luminous efficiency is obtained. Currently, there are several types of lamps available, different in several aspects: luminous intensity, reproduction colors, energy efficiency, physical composition, method for emitting light, specific purposes, prices, among others. It is worth mentioning that the lamps differ from each other not only by the different luminous fluxes that they radiate, but also by the different powers they consume. In order to compare them, it is necessary to know how many lumens are generated per absorbed watt. This greatness is called energy efficiency. Thus, the proposal of a study was evidenced, in order to promote these luminous resources, in addition to emphasizing their economic viability.

NIGHT-SKY BRIGHTNESS IN BURKINA FASO: OUAGADOUGOU LIGHT POLLUTION ASSESSMENT AND IMPACT ON THE STARRY SKY OBSERVATION .

The quest for well-being and improvement of the populations living conditions in the borders of the big cities have changed habits in terms of lighting. The use of LED lamps and the reduction in the cost of photovoltaic panels, have allowed easy access to electricity nowadays. The lack of education on the nature of outdoor lighting has unfortunately led to an increase of light pollution. This study uses VIIRS DNB Free Cloud Composites imagery to perform light pollution in Burkina Faso mainly in Ouagadougou, the main cities and surrounding areas. VIIRS imagery data obtained have been processed to get information of light pollution by classifying the information into several classes presented in a map. Using VIIRS images, we show that light pollution has increased by 20% in Burkina Faso in major cities such Ouagadougou. Despite the fact that the illuminated surface per thousand inhabitants, ~0.09km2, remains almost stable over the years. Areas of the city experience a decrease (<1%/year) in nighttime light while some areas have an explosion up to 50nW/cm2sr a year due to the presence of new infrastructure. Light pollution increases inside the city and the observation of the night sky becomes quite difficult in the inner city and still feasible on the outskirts of these cities.

The epidemiology of myopia in school children worldwide.

AbstractPurposeBoth genetic and environmental factors play a role in the increasing prevalence of myopia. This modern rise mirrors the trend of children spending a considerable amount of time reading, studying or—more recently—being glued to computer and smartphone screens. The aim of this study is to present an update on the current epidemiology and risk factors for myopia in school children in different countries around the world.MethodologyPubMed and Medline were searched for the following keywords: prevalence, incidence, myopia, refractive error, risk factors, children and visual impairment. English language articles published between Jan 1, 2013 and Nov 30, 2018 were included in the study. Studies were critically reviewed for study methodology and robustness of data. Seventy‐nine studies were included in the review.ResultsPrevalence remains higher in Asia (60%) compared with Europe (40%) using cycloplegic refraction examinations. Studies reporting on non‐cycloplegic measurements show exceptionally high myopia prevalence rates in school children in East Asia (70%–80%) compared with North America (42.2%). Low prevalence under 10% was described in African and South American children. New risk factors, apart from outdoor time and near work exposure, such as dim light, the use of LED lamps for homework, low sleeping hours, reading distance less than 25 cm and living in an urban environment were described in recent studies.ConclusionsThe high rates of myopia prevalence among school children, especially Asian populations, are strongly influenced by particular lifestyle habits. Increase in outdoor time remains the best strategy to prevent myopia onset. Additional epidemiological studies should be carried out on implementation of public health strategies to tackle and avoid myopia onset. High‐risk populations with high myopia prevalence might need a combined approach of increased outdoor time, changes in near distance activities in preschool children and treatment to control myopia progression.

Economic Feasibility Study Generated on Replacing Tubular Fluorescent Lamps with Led Lamps in a Commercial Building

The present study has as main objective to verify the reduction of electric energy consumption, allied to the possible economic-financial and environmental benefits that are associated with the use of LED lamps in a commercial building, where it develops office activities covering only part of the building. , which served as the experimental basis for the application of the case study, initiated after a survey of the electrical and constructive characteristics of the luminaires installed on site. In research conducted in the local market specialized in the subject, we selected lamps that are more easily found, analogous to those already installed, manufactured by traditional companies in the field. The monitoring of lighting loads was made by measuring by specific equipment and simulation of energy billing according to the rules of calculations established in rules governed by government agencies and tariff framework in which the building is in both scenarios, before and after lamp replacement. Providing financial technical evaluation through the use of indicators that show the viability of this substitution.

Selecting lighting system based on workers’ cognitive performance using fuzzy best–worst method and QUALIFLEX

The present study aimed to evaluate different illumination systems in the control room of a power plant and decide on the optimal illumination system in terms of the operator’s cognitive performance. This study was conducted on a control room, consisting of 16 operators. The cognitive performance and sleepiness of the subjects were evaluated under three illumination systems: fluorescent lamps (230 lux); fluorescent lamps and LEDs (415 lux), and LEDs (210 lux). The weights of the criteria determined by the FBWM and systems were ranked using the QUALIFLEX. In the morning shift, the simple cognitive function (FDST) and the complex cognitive function (BDST) indices for the fluorescent and LED-illumination system showed the best values. In addition, in the evening shift, the FDST index for the fluorescent and LED-illumination system and the BDST index for the fluorescent illumination system showed the best values. Results related to the weight of each criterion indicated that BDST with the weight of 0.665 is the most important criterion, and then FDST, with the weight 0.2, was placed at ranks 2. The results of this study showed that the best cognitive performance for control room operators provided by combined fluorescent and LED-illumination systems in the morning and fluorescent system in the evening. It is suggested that more appropriate conditions should be provided for individuals in terms of cognitive performance by adding LEDs to the traditional fluorescent systems in the control rooms and setting the appropriate time for the use of LED lamps.

Experimental Characterization of Close-Emitter Interference in an Optical Camera Communication System.

Due to the massive insertion of embedded cameras in a wide variety of devices and the generalized use of LED lamps, Optical Camera Communication (OCC) has been proposed as a practical solution for future Internet of Things (IoT) and smart cities applications. Influence of mobility, weather conditions, solar radiation interference, and external light sources over Visible Light Communication (VLC) schemes have been addressed in previous works. Some authors have studied the spatial intersymbol interference from close emitters within an OCC system; however, it has not been characterized or measured in function of the different transmitted wavelengths. In this work, this interference has been experimentally characterized and the Normalized Power Signal to Interference Ratio (NPSIR) for easily determining the interference in other implementations, independently of the selected system devices, has been also proposed. A set of experiments in a darkroom, working with RGB multi-LED transmitters and a general purpose camera, were performed in order to obtain the NPSIR values and to validate the deduced equations for 2D pixel representation of real distances. These parameters were used in the simulation of a wireless sensor network scenario in a small office, where the Bit Error Rate (BER) of the communication link was calculated. The experiments show that the interference of other close emitters in terms of the distance and the used wavelength can be easily determined with the NPSIR. Finally, the simulation validates the applicability of the deduced equations for scaling the initial results into real scenarios.

English

This study aimed to compare the performance of incandescent lamps and LED lamps, regarding the consumption of electricity and the economic viability of these lighting systems in broiler houses in western Parana State, Brazil. The study was conducted to compare the power consumption in two broiler houses of the dark house type in Sao Miguel do Iguacu, Parana, Brazil; one lighting system with incandescent lamps and the other one with LED lamps. The power consumption was measured in the two lighting systems, using meters of electrical quantities Landis Gyr+ during the housing period of a batch of poultry corresponding to 43 days. Then, the energy consumption was calculated per bird housed, by mass of live chicken and aviary unit area. With the electricity tariff values for rural consumers, there was an evaluation of the economic viability of lighting systems by the method of net present value (NPV) method and the discounted payback. The main results showed that throughout the period of broiler chickens housing, in the aviary with incandescent lamps 1,768 kWh in lighting was consumed, while the aviary with LED lamps consumed 221 kWh. The economic feasibility analysis showed that the use of LED lamps presented greater economy, and has a return on investment within a period of 21 months. Key words: Energy consumption, lighting systems, broiler house.

Newer Aspects in Phototherapy

The concept of phototherapy has undergone a lot of changes in the past 30 years. It started with the emergence of psoralen ultraviolet A (PUVA) for the treatment of psoriasis. The subsequent evolution of Narrow band UVB therapy, Targeted phototherapy, UVA1 therapy, Home phototherapy and the use of LED lamps have revolutionized the treatment of various skin diseases. This article briefly summarizes the advances made in the last few years in the field of phototherapy.Nepal Journal of Dermatology, Venereology & Leprology, Vol.14(1) 2016, pp.5-8

Green Hospital; From Tubular Lamp (TL) to Light Emitting Diodes Lamp (LEDs) a Brief Critical Review

The Use of TL Lamps – TL lamps immediately gained popularity defeat fluorescent lamps. This is also supported by the ability of TL lamps in saving energy. TL lamps can provide light equivalent to 60 W of fluorescent lamps with a power of only 13-15W. This means that energy saving of TL lamps is five times higher than fluorescent lamps.TL Lamps and Environmental Issues – TL lamps raises new problems for the environment. The first problem comes from the mercury content in the form of vapor in the tube. When broken, TL lamp emit mercury vapor with a concentration between 25 thousand ng / m3 to 100 thousand ng / m3, much higher than the threshold concentration of mercury in the air that is only 300 ng / m3.The Use of LED Lamps – LED lamp is a lamp that is superior to TL lamp because it can live longer than TL lamp. LED lamp is a lamp that is superior to TL lamp because it can live longer than TL lamp. While fluorescent lamp is only survive in 750-1000 hours and TL lamp for 6-15 thousand hours, the LED lamp is able to live up to 50 thousand hours.LED Lamps and Environmental Issues – LED lamp has provided great energy solutions for environmental problems. The amount of emissions generated by LED 2.3 times less than TL lamp and 10 times less than the greenhouse gas emissions of a fluorescent lamp. Another advantage that cannot be faced by TL lamp is LED does not contain mercury.Conclusion – The LED light is much better than fluorescent lamp and better than the TL lamp in addressing environmental problems. That LED is better for global warming reduction efforts rather than TL lamp.

Calculation of harmonic losses and ampacity in low-voltage power cables when used for feeding large LED lighting loads

A numerical investigation on the harmonic disturbances in low-voltage cables feeding large LED loads is reported. A frequency domain analysis on several commercially-available LEDs was performed to investigate the signature of the harmonic current injected into the power system. Four-core cables and four single-core cable arrangements (three phases and neutral) of small, medium, and large conductor cross sections, with the neutral conductor cross section approximately equal to the half of the phase conductors, were examined. The cables were modelled by using electromagnetic finite-element analysis software. High harmonic power losses (up to 2.5 times the value corresponding to an undistorted current of the same rms value of the first harmonic of the LED current) were found. A generalized ampacity model was employed for re-rating the cables. It was found that the cross section of the neutral conductor plays an important role in the derating of the cable ampacity due to the presence of a high-level of triplen harmonics in the distorted current. The ampacity of the cables should be derated by about 40 %, almost independent of the conductor cross sections. The calculation have shown that an incoming widespread use of LED lamps in lighting could create significant additional harmonic losses in the supplying low-voltage lines, and thus more severely harmonic emission limits should be defined for LED lamps.

EFFECT OF SUPPLEMENTARY LIGHTING ON THE QUALITY OF TOMATO FRUIT (SOLANUM LYCOPERSICUM L.) IN AUTUMN-WINTER CULTIVATION

One of the most important factors affecting many physiological processes including the intensity of photosynthesis and thus a proper growth, development and quality of plants is light. Chemical investigations carried out for various vegetable species (lettuce, tomato cucumber) revealed that the use of LED lamps positively affected their growth and phytochemical traits. The present work aims at comparing the effect of supplementary lighting type on the chemical composition and sensory quality of tomato fruits cultivated in the autumn-winter season. Two greenhouse tomato cultivars (‘Komeett’ F1 and ‘Starbuck’ F1) were used in this experiment. Fruit quality was evaluated by the content of total sugars, dry matter, nitrate (NO3), phosphorus and potassium. Sensory analysis was carried out using the profile method (QDA). The use of a supplementary light source increased the content of total sugars in ‘Komeett’ F1 cultivar fruits by 39.4% for HPS and 17.9% when LED light was used. The dry matter content in fruits was at similar level. A lower content of nitrates in tomato fruits was observed in the combinations where plants were lighted with HPS as well as LED lamps. However, there was not a significant effect of supplementary lighting on phosphorus content in tomato fruits. Cultivating tomato with supplementary light significantly affected the fruit sensory quality. Plants supplementary lighted with HPS and LED lamps were characterized by fruit with higher flesh juiciness, sweeter taste and higher overall quality.