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This article deals with the design, development, and analysis of a wireless power transfer system prototype based on capacitive coupling. The system is intended for the continuous charging of a suspended mine drivetrain. It consists of a resonant inverter, primary and secondary matching circuits, a suitable capacitive coupler, and a rectifier with a load, ultimately serving as a battery charger for a mobile energy storage device. The system successfully achieved the target output voltage of 320 V and a charger output power of 2 kW at an operating frequency of 300 kHz. Additionally, the total system efficiency was at the level of 60%, ensuring that the RMS voltages on passive components remained below 3 kV. [ABSTRACT FROM AUTHOR]

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In an overwhelming number of cases, the closure of a coal mine in Poland, for safety reasons, requires the installation of a pumping station and systems for the drainage of inflowing water due to its connection via roadways, goaves, or water-leaking pillars with other adjacent active mines. Due to operational costs, stationary pumping stations are being replaced with submersible pumping stations, wherever the geological/mining conditions allow this. The key factors to be considered when designing a submersible pumping station include the estimated water influx and the storage and emergency reservoir fill-up time. If the water level in the emergency reservoir exceeds the level of the maximum ordinate, there is the risk of water flooding an adjacent active mine, which poses a serious safety risk to this mine. A pumping station design must ensure that water can be pumped out also in emergency situations and must ensure permanent control over the level of the water table. The pumped-out water, after potential treatment, can be utilized as technological water in industrial plants. In the designed pumping station, it is also feasible to establish underground pumped-storage hydropower. This would enable the storage of energy from renewable sources, thereby contributing to CO2 emission reduction. [ABSTRACT FROM AUTHOR]

The article describes issues related to the development of a sensor measuring the distance from the end of the shield support canopy to the face of the longwall panel. The sensor's task is to detect rock falls because in such a case, empty spaces in the coal seam below the roof are generated. The sensor is a part of the system which task is to predict unfavourable behaviour of the longwall roof affecting the continuity of mining. Due to an untypical workplace and difficult conditions prevailing there, it was not possible to use a typical sensor. The ultrasonic technique was used for this purpose. The next research stages related to the development of the sensor were described. Tests of various types of ultrasonic transducers, working at different parameters, were described. Only transducers with a closed structure were considered because they can operate in the presence of high dustiness and humidity. The sensor casing was adapted to a specific type of shield support. The installation location should not be accidental, as an additional hinged shield is mounted at the end of the canopy, which is an obstacle in the measuring track and can even completely cover it, making measurements impossible. The sensor is mounted close to the side edge of the shield support canopy using small free space, enabling a measurement. Structural elements of the canopy are obstacles in the measuring track and are a source of interference of the received signals. The ultrasonic transducers are built-in tubes, which direct the ultrasonic wave and amplify the received signals. The results of laboratory tests of the model of the path measurement sensor are presented. They describe the impact of analysed aspects, i.e. the type of transducers used, the structure of the surface that the wave is reflected from and the mechanical solutions on the quality of received signals. A prototype of a sensor installed on shield support is presented. [ABSTRACT FROM AUTHOR]