ISSN 1805-3386

April 6, 2020


2014 No.2

Investigation of DC and AC Energy Transfer Transients for Ultra Deep Wells

Rafajdus, P., Vavrúš, V., Kúdelčík, J., Dobrucký, B.

This paper deals with the investigation of DC and AC energy transfer transients for ultra deep wells. Two transfer energy approaches are described: DC and AC three phase systems transmission via power cable. The transients could be switch on, switch off for no load, rated load and over load conditions. The simulations analysis of both systems are described and compared. The losses are calculated and discussed.


Keywords: Energy transfer for ultra deep wells, DC and AC transient analysis.


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Losses in Sinusoidal Filter for Pulse Controlled Converters

Novák, J., Chyský, J., Kořínek, P.

This paper presents three methods losses evaluation in magnetic circuits of sinusoidal filter chokes and their experimental verification. The attention is focused on losses caused by higher harmonics in context of frequency pulse width modulation. Methods based on the calculation of the reference loss method are described, they are based on direct measurement using an integral of instantaneous power losses and determining of them from temperature rise characteristic.


Keywords: Sinusoidal filter, dissipation losses, choke, higher harmonic components.


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Overview of Slip Control Methods Used in Locomotives

Pichlík, P., Zděnek, J

Modern locomotives are more powerful and reaches higher speeds. With these parameters increasing it is connected a problem with transmission of the tractive effort between vehicle wheels and rails. The maximum value of the transmitted force depends on value of the wheel slip velocity and its type of control. In the paper problem of the force transmission and some used control methods are briefly described. The simulation in Matlab/Simulink is also one of the described methods.


Keywords: Adhesion Characteristic, Slip, Slip Control, Tractive effort.


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Advantages of Synchronous Reluctance Motors

Matyska, P

Synchronous reluctance motors are a new range of standardized electric motors developed by ABB for utilities and industrial consumers to improve their system performance and efficiency along with the benefit of being able to lower their footprint on the environment. These motors, which are delivered to customers in full package combined with frequency converter combines the performance and efficiency of permanent magnet technology with the simplicity, cost-efficiency and service-friendliness of induction motors. An innovative rotor construction brings lower losses and allows to use higher density of power in the motor construction. These motors are delivered in variant with efficiency accordance to IE4 efficiency level and in variant high output, which is characterised with high concentration of density.


Keywords: Synchronous reluctance motors, M3BL, reluctance, efficiency, losses.


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Determination of the Value of the Capacitive Earth -Fault Current in Distribution Networks Operated with Isolated Neutral Point

Žák, F

The new indirect method of measurement and calculation of the phase-earth capacity in networks with isolated neutral point is based on creation of a short-term phase capacity asymmetry in the network. The value of the phase earth capacity in the network can be determined using the voltage ratio in the network and the capacity value of the connected capacitor. When expanded, the method can be also used for the leakage current estimation. Furthermore, this method can be applied to periodic controls of the earth capacitive current value. For the evaluation of the phase earth capacity, a single-purpose automation can be used and thus the whole process of measurement and evaluation is conducted at a defined period (at a given hour, day, month…) or on operator’s command.


Keywords: Isolated neutral point, capacitive earth-fault current, measuring and calculation of phase earth capacity value.


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Mathematical Model of Induction Motor with Ferromagnetic Rotor

N. Zablodskiy, N., Pliugin, V., Skryl, V., Lettl, J.

Results of theoretical and experimental research as well as outcome of simulation by means of the established mathematical model of induction motor with ferromagnetic rotor in static and transient states are presented and analyzed.


Keywords: Induction motor, hollow ferromagnetic rotor, mathematical model, transient, simulation.


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