Vaclav Kolar

Measurement of ground currents leaking from DC electric traction

This paper deals with measurement of stray currents caused by electric tramways. Stray currents can significantly contribute to corrosion of metal devices buried underground. This paper focuses on measurement of currents leaking into the ground from a tramway track. It describes Ohms method based measurement method, measuring apparatus and a device that is used to determine rail resistance as well as an actual measurement on a tramway track.

Suggestion of long-term measuring of daylight contributions in interiors

The confirmation of the prediction system model of economies in illumination systems with regulation for constant illuminance required the realization of a measuring device for long-term measuring of illuminance in interior workplaces. The suggested system makes this measuring possible in 10 points of interior and at the same time outdoor on the plain without shadows.

Testing the properties of illuminance sensors designed for controllable lighting systems

Abstract Currently, when the price of electric power keeps increasing, it is very effective to control a lighting based on pre-programmed requirements depending on the actual value of illuminance. To be able to perform such control, it is necessary to measure the illuminance value as accurately as possible. This paper deals with testing of several low-cost industrial sensors of illuminance intensity. There is a detailed description of industrial illuminance sensors of the lighting labelled MAX44009 and TSL2561. These sensors provide information about the illuminance intensity in a digital form and communicate via serial I2C communication. The results of photometric measurements of both sensors give satisfactory results. In the future it is planned to use these sensors in FARCOM-ECO system of firm TRAKCE to control illuminance levels in the platforms and train yards. The control of illuminance will significantly reduce an energy consumption of the lighting systems.

Development of measuring instruments for long-term measurement of low level illuminances and luminances

The paper deals with long-term measuring instruments for light data collected under the night sky. The point of such measurements is to quantify the obtrusive light and compare the level of the obtrusive light in populated industrial areas and out of them. For long-term measurements of low level illuminances (about 10-2 lx) and luminances (about 10-3 cd/m2) should be applied not only the measuring instruments with high sensitivity, but also completely independent instruments with the ability to save the measured data. For low level illuminances measuring is described luxmeter satisfying the above requirements. The issue of measuring the low luminances is solved by digital photographs. In this paper is also showed the astronomical camera with cooled CCD chip, which is able to minimize the thermal noise. The last described device for long-term measuring of the night sky is astronomical instrument (Sky quality meter), which evaluates the luminances of the night sky. This instrument does not work with lighting units (cd/m2), but in magnitudes (mag). For traditional reasons, astronomers use the term magnitude, expressed in units called magnitudes. Magnitude is a logarithmic value. This instrument is able to compare the astronomical measurements and lighting ones. For illuminances measurement is needed photovoltaic sensor capable to convert low illuminances to electricity. Nowadays luminance measurements with the digital photography is very effective in levels from 1 cd/m2 to 100 000 cd/m2. However, for measuring of very low level luminances it is not enough and there must be used very sensitive CCD cameras with cooled chips.

Prototype of a low-cost luxmeter with wide measuring range designed for railway stations dynamic lighting systems

The paper presents the development of a low-cost luxmeter designed for usage in automatic applications for continual (long-term) measurement of illuminance. The measured information is used to adjust the level of lighting systems of artificial lighting on railways (platforms, marshalling yard, tracks etc.). The reason of this measuring device is a requirement for massive deployment of dimmable lighting systems for railways, in order to limit the maximum energy consumption. Due to the requirements for its deployment it is necessary to put particular emphasis on its low cost, reliability and universality, not accuracy. The concept of the device is designed so that it can transmit measured data especially in the FARCOM-ECO system, which is used to control of technological processes on the railways in the Czech Republic.

Simulation and measurement of selected electrical parameters for electric drainage

Electric drainage is used for the protection of underground devices (e.g. pipelines) against the negative effects of stray currents caused by DC electric traction. When flowing out from the underground device and returning to rails, stray currents contribute to the corrosion of this device. Using electric drainage can help to significantly eliminate these negative effects. Electric drainage provides a conductive connection between the underground device and electric traction rails, so that current does not leak into the ground, but flows through this connection. This will eliminate the negative effects of stray currents. More advanced drainage solutions include polarised drainage and regulation drainage. Currently, these devices are based on power electronics. To ensure correct and economical dimensioning, it is necessary to find out voltage and current parameters on site. This paper deals with the measurement and simulation of electrical parameters in the process of designing electric drainage.

Development and implementation of an intelligent system for permanent evaluation of light fixtures in a lighting system of transmission system substations

Substations in the transmission system operated by ČEPS, a.s. are currently being modernized and a new system is being developed to ensure control, management and monitoring of lighting systems. This paper includes information about the development of the new monitoring system, especially with regard to ensuring secure and reliable communication between measuring systems and the central control system. The operation of substation lighting is monitored by PAC control system, which makes it possible to investigate different types of lighting. The use of PAC control system is aimed at ensuring reliable operation and control of outdoor lighting, as well as at the monitoring and investigation of remote control lighting systems in the transmission system substation. In this way, better control, greater safety and more effective maintenance may be achieved.

Electric railways operation from the perspective of EMC

The paper briefly summarizes the classification of three-phase electric systems and explains the Fortescue theory. It also includes a description of measuring apparatus, created with the use of virtual instrumentation, which was used for measurements at a railway transformer substation. The paper includes the results of unbalance measurements at the transformer substation of Railway Infrastructure Administration.

Solution of problems with short lifetime of airfield halogen lamps

This reason to carry out this investigation was a complaint from international airport about increased maintenance cost and insufficient reliability of runway lighting systems. The exhaustive investigation of overall lighting installation was carried out, which comprises lighting parameters, mechanical parameters and electrical parameters. The possible causes of luminous flux drop and significantly lowered mean time between failures have been explained. These causes were presented as observed mechanical and electrical changes of incandescent lamp filaments, for current source power supply, which is utilized in runway lighting system.

The design and the development of a low-cost luminaire in order to achieve the best light-technology parameters (Ra ≫ 80) and a life-time period

This paper deals with the operating of so called low-cost lighting systems fitted with LED light sources. The reason for drawing up the paper was a notification of qualitative changes in luminous flux of implemented lighting systems. It is currently possible to produce relatively cheap LED luminaires fitted with available white LED. Since the low-priced LED go hand in hand with their qualities, these cheap light sources might affect negatively the overall perception of the illuminated space. Therefore it is necessary to explore these light sources in details. The paper shows the design and development of an inexpensive luminaire so as to achieve not only the best possible light-technical parameters, but also its life-time period.