Tomas Mlcak

Optimization of Drive Unit through Load Measurement

The basis is a device that contains tension sensor. The output of tension sensor is associated with the input control unit. The tension sensor is connected between the two loads. The sensing signal is processed using a PC measuring card with special software. The resulting device will be part of trains. Data sensing by this device will be transmitted from the PC to the control unit.

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.

Selecting a suitable controlling algorithm for a regulated electric drainage

Electric drainage is used to protect devices which are buried underground (such as piping) from the negative effects of DC electric traction induced stray currents. In places where stray currents leave the underground device and return into rails, they contribute to the corrosion of buried devices. Electric drainage is one of the possibilities to minimise these negative effects. Electric drainage is a conductive connection between the buried device and electric traction rails, which ensures that current does not flow from the device into the ground, but it flows through this connection instead. Currently, the most widely used type is regulated electric drainage. In most cases, current is regulated by pulse width modulation (PWM). When this modulation is used, the current flowing through the drainage contains harmonic components with different frequencies. Track circuits are often used on railways, as an important part of the track security system. For secure operation, it is necessary to make sure that frequencies generated by the drainage do not interfere with track circuits. This paper deals with the design of a regulated drainage control system, with regard to its compatibility with track circuits. The paper contains results of computer simulation, as well as those of on-site measurements carried out on a prototype installed on a tram track.

The development of a modern heat treatment unit with embedded control ensuring minimal retroactive effects on the supply network

Within the frame of research, our team realized a comprehensive development for modernisation of the heat treatment unit “RETEP” in cooperation with the company Svarservis Group. A heat treatment unit is a device used mainly to heat welds in mechanical engineering, energetics and during fabrication of technological units but also to a lot of other applications. This article describes the development of control circuits of power solid-state relays of the heat source including algorithms of control. The implementation of algorithms of two ways of controlling was done - phase control and full-wave control - as well as their comparison. A new switching algorithm was developed for the method of full-wave control, which ensures the required equal distribution of performance with load. The whole question was also dealt with to limit at the most the negative influences on the supply network. The negative influence of harmonic components was nearly completely eliminated in the newly developed algorithm for full-wave control. That is why it is also possible to use this modern newly developed heat source in public distribution network in case the compatibility levels required by the standards are observed. The validity of the whole solution was proved by experimental measuring.

Measurement and simulation of stray currents caused by AC railway traction

The topic of this paper is currents leaking from electric railway tracks into the ground, where they cause the so-called “stray currents”. This paper focuses on the measurement of these currents in AC railway in real life conditions. Computer simulation of the problem is also included. At the end, measurement and simulation results are compared.