Petr Bos

Comparison of LED properties, compact fluorescent bulbs and bulbs in residential areas

A significant share of total electricity consumption at home is lighting, which can use up to 15% of total consumption. But it is possible to achieve significant savings if we choose the right light sources. Every room in the house or apartment has different requirements for light, and also different light sources have different light properties. Correct selection of sufficient and energy-saving lighting is not simple, and therefore it should be carefully considered.

New outdoor lighting — Operation and maintenance

This article deals with operation and maintenance of lighting in substation of transmission system. In the first part, indoor work places lighting in substation building are described. The second part is aimed at new outdoor work places lighting - fence lighting, road lighting and lighting of work places. New substation lighting system can be monitored and diagnosed during its operations. Condition of luminaires are essential for the inspection and common maintenance - Condition Based Maintenance (CBM).

Correlated Colour Temperature Changes of the LED Sources Depending on the Angle of Their Radiation

The aim of the report is a description of an issue connected with subjective perception of colours from the light of the lighting systems stepped by LED. Subjective observation of the colour change on the light of the lighting systems stepped by LED has been mostly related to extensive lighting systems where it was possible to observe identical light source (LED) within various angles. This phenomenon was manifested even more distinctively within lighting systems that made use of optical systems located in luminaries (reflector, diffusers) in a minimal way. Additional optical systems redistribute primary luminous flux coming from light source (LED) and thus there is a blending of luminous flux radiated to a certain angle of the illuminated space from various directions of the luminous flux radiation itself. In case it is not like this and the luminaries are equipped only with LED with a suitable luminous distribution curve, there is no blending of the luminous flux. Thanks to this the observer can also perceive various colours of light within individual luminaries perceived under various angles.

Outdoor power stations CCTV systems that work synergistically with the security lighting

At present time, in the operation of the outdoor electric power stations providers access their unattended operation. Linked to this there is necessary to know what is happening in the station not only during the day, but especially at night. Since the operation of the entire lighting system in normal operation is highly uneconomical and generates light pollution too, the solution is that in permanent night operation is only lighting system providing illumination around the fence for security cameras and for visibility of the borders of power station from outside. Synergistically with this type of lighting should be set up security cameras system providing information about potential disruption perimeter of the power station. The article deals with the proper selection and mutual synergy of outdoor lighting systems and security cameras system. The issue is not only in the power stations, but generally in using of the cameras systems in industrial applications which are dependent on artificial lighting. Main chapters of the article will solve following problems. At the beginning it is necessary to describe the need to choose the color of light of artificial lighting system to spectral sensitivity of chips inside the cameras. It will continue with recommending for a design of artificial lighting system with respect to the placement of cameras. It means the design which calculates not only with horizontal illuminance, but cameras (vertical) illuminance too. The camera illuminance is necessary for recording of images the whole distance between the luminaires. The whole policy of illumination for cameras must be re-evaluated compared to standard public lighting systems design. In the last part of this article will be described relations between the horizontal illuminance, the camera illuminance, luminance and illuminance on the camera which are given by manufacturers.

Increasing of visibility on the pedestrian crossing by the additional lighting systems

Pedestrian crossings are critical places for road accidents between pedestrians and motor vehicles. For this reason, it is very important to increase attention when the pedestrian crossings are designed and it is necessary to take into account all factors that may contribute to higher safety. Additional lighting systems for pedestrian crossings are one of them and the lighting systems must fulfil the requirements for higher visibility from the point of view of car drivers from both directions. This paper describes the criteria for the suitable additional lighting system on pedestrian crossings. Generally, it means vertical illuminance on the pedestrian crossing from the drivers view, horizontal illuminance on the crossing and horizontal illuminance both in front of and behind the crossing placed on the road and their acceptable ratios. The article also describes the choice of the colours of the light (correlated colour temperature) and its influence on visibility. As a part of the article, there are case designs of additional lighting systems for pedestrian crossings and measurements from realized additional lighting systems by luxmeters and luminance cameras and their evaluation.

Suggestion of the methodology for verifying the outputs of different measuring groups evaluating light parameters of public lighting

The reason to create this article was the need to make a methodology which would enable verifying not only lighting systems of public lighting but also measuring groups, which make these measurements. The methodology is suitable especially for administrators of big lighting systems of public lighting because it can verify for them qualitative and quantitative light-technical parameters of new lighting systems of more measuring groups. An administrator (operator) of public lighting should have information not only about measuring devices (accuracy rating, calibration), which are used by measuring groups, but also have information if there are no mistakes in the choice of measuring points, setting of measuring devices and data evaluation. These mistakes can lead to incorrect evaluation of lighting parameters of lighting systems of public lighting.

The evaluation of light parameters in the public lighting in the sphere of mesopic vision

Recently more and more specialists deal with questions of the road lighting. They design methodics that should be followed during the projection of the public lighting. The way of projection of road lighting according to the newest norms is more effective, it eliminates lighting pollution and helps to reach safer operation. The road lighting is a specific case of lighting system where an observer stands in the area of rather low adaptation luminance. That means that lighting parameters of road lighting system are not evaluated according to the photopic curve of human eye sensitivity but according to curves that can be found in mesopic area of sensitivity. Therefore a measurement of roads lighting was carried out. Here the illuminance was evaluated according to a chosen mesopic curve of sensitivity of human sight that was chosen according to the level of the observers adaptation luminance. In terms of observation of changes in sensitivity of the human eye during conversion from photopic to mesopic vision it is necessary to point out the fact that it is a peripheral area of the human eye. The central part of the eye (fovea) must be excluded from the observation of these changes as there are only photoreceptors (cones) of photopic sight to be found in this area.

Potential Influence of Light Sources on Human Circadian Rhythms

The article deals with examining light sources used in households from the point of view of their potential influence on circadian rhythms. Nowadays, there are lots of different types of light sources available on the market with different light colours. An inadequate choice of the colour of the light source can result in worsening visual comfort, which can lead to disturbing circadian rhythms. When choosing light sources, it is necessary to take into account the purpose of the room for which the lights are chosen. Especially, it is a question whether LED sources with similar quantitative and qualitative characteristics have stronger influence on circadian rhythms than classical light sources or not. The reason is primary radiation even of white LED in the blue part of visual spectra. The circadian receptors are the most sensitive in the area.

Statistical Evaluation of Dimmable Interior Lighting System Consumption Using Daylight

From the power engineers point of view, at the present time, the necessity to predict the consumption of lighting systems becomes more and more urgent at the time of the project phase. The reason is to compare the projects from different investors and especially to compare the projects with regulated (dimmed) lighting systems (these are regulated at a constant level of illumination) with the projects of unregulated lighting. In that case, the designer has to be able to determine the payback of regulated lighting system in comparison with classic unregulated lighting systems. Nowadays, it is possible to calculate the potential savings. The calculating is determined by the LENI (Lighting Energy Numeric Indicator), according to EN 15193, which is based upon the analytical estimate of potential savings calculated on the base of empirically derived coefficients for standardized rooms, standardized operations, etc. However, this model is not based on real specific situations. Therefore, the team of VSB-TU Ostrava developed a predictive model, which is based on the daylight dynamics in specific lighting conditions. The long-term measurements were carried out to verify whether the model´s results correspond to the real facts. The statistical evaluation of the model´s conclusions and the real measured rates was carried out as well.

Selection of lighting systems in outdoor electrical stations working together with camera systems

When installing outdoor surveillance camera systems, a suitable choice and setting of outdoor lighting are important to ensure the right functioning of a camera and a legible and sharp picture. To these camera systems could transmit relevant visual information in the electric station is necessary correctly settings of illumination. The paper deals with the necessity to cooperate lighting system watchdog lighting and camera system and is discussed the sensitivity of cameras and their requirements for illuminance and luminance. Standard values of speed of monochrome camera chips are around 0.1 lx and for colour chips around 1 lx. Values of monochrome sensors are one digit place higher than of colour sensors so they are convenient especially for bad light conditions. Is necessary to explain that higher described illuminance are on the camera chips and not on the working places.