In areas where urban tracks are used as public transportation, dynamic stray currents cause high maintenance costs for the tracks and metal structures near the tracks. S tray currents caused by rail vehicles depend on many factors (traffic density, vehicle speed, acceleration and deceleration, soil and track moisture), so it is very difficult to get a clear picture of the harmfulness of the stray current based on the results of a single field measurement. However, there are several measurement methods that can be used to determine the presence of stray currents and predict appropriate track maintenance actions. Some of these methods are described in this article, namely the use of stray current mapper, measurement of rail potential and rail current, measurement at the stray current collection system, and the use of non-destructive sensors. In track construction, measuring the electrical potential between rail and ground is one of the most common methods of detecting the damaging influence of stray current.

This paper deals with developing and implementing a bidirectional galvanically isolated on-board charger of a high-power density. The power density of the new charger was 4 kW/kg and 2.46 kW/dm³, and the maximum efficiency was 96.4% at 3.4 kW. Due to the requirement to achieve a high-power density, a single-stage inverter topology was used. Regarding switching losses, due to the topology of the circuit with so-called hard switching, the switching frequency was set to 150 kHz. A laboratory prototype was built to verify the properties and operating principles of the described charger topology. The on-board charger has been tested in a microgrid test platform. Due to the parasitic properties of the transformer and other electronic components, overvoltage with subsequent oscillations occurred on the primary side of the transformer and damped resonance on its secondary side. These parasitic properties caused interference and especially voltage stress on the semiconductor elements. These undesirable phenomena have been eliminated by adding an active element to the charger topology and a new transistor control strategy. This new switching control strategy of transistors has been patented.

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.

Within the research activities, the realization team did the complete development of the annealing source with the aid of modern technology and components, such as the programmable logic controller, industrial PC, and microcontrollers, to secure the intelligent way of switching the power semiconductor switches (SSR relays) with the regard of minimizing the low frequency conducted disturbances. The annealing source has the implemented algorithm for two ways of output power control, i.e. phase control and full wave control. The algorithm of the full wave control is designed in a way so as to arrange the balanced power in the load. By using this way of control, the harmonic emission is almost entirely eliminated, but the influence of the flicker effect will surface. The article offers a complex view at the annealing source from the control method perspective, ensuring the correct annealing cycle and subsequent influence of the annealing source to supply network. It deals deeply with EMC analysis for both ways of designed annealing source control. The analysis comes out from the experimental measurements on the functional annealing source prototype.DOI: http://dx.doi.org/10.5755/j01.eie.23.5.19239