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Durability and reliability of cable lines is related to the quality of insulation materials, proper installation and maintenance during operation, as well as its mode of operation and not least by the action of degradation factors during operation. Neglecting any of these factors can significantly shorten the designed life or cause damage during operation. Producers in technical terms normally guarantee...
Absorption current measurements and very low frequency dielectric measurements were performed to evaluate the insulation properties of halogen free fire retardant cables at various temperatures. Changes of electrical parameters have been used for the cables characterization and comparison. The results of measurements proved a complex character of the dielectric phenomena, which consist of several...
This paper investigates the electrical breakdown of biaxially oriented polypropylene (BOPP) film during accelerated DC and thermal ageing. The DC breakdown voltage of 6.5 μm thick capacitor grade polypropylene (PP) films was measured. Two types of films with different crystallinity were tested. 88 breakdowns per sample were collected. The scale and shape parameter of the Weibull distribution were...
The implementation of Reliability Centered Maintenance into Preventive Maintenance Plan scheduling is one of the possible paths towards cost reductions in the fields of diagnostics and operating personnel. There is also the assumption of maintaining acceptable reliability of individual devices within the entire network. The devices to be considered suitable for application of RCM concern network elements...
Companies in field of electricity distribution and transmission recently deal with the need for decreasing cost of operation in terms of both capital and operational expenditures. They start to use statistically driven approaches of asset management to support these requirements in a way that reliability of the grid is being kept on the same level or even improved. However, the behavior of the assets...
This paper focuses on modelling and subsequent comparisons of co-generation units with combustion engines. It provides substantial information about co-generation units. The document refers to a simulated co-generation unit delivering the power of 600kWe/657kWt, 1200kWe/1191kWt and 2000kWe/1990kWt.
Mining networks are subject to high requirements in terms of operational reliability and safety. The occurrence of ferroresonances in the network is one of the causes of instrument transformers being overloaded, which can cause their damage. Therefore, it is necessary to avoid this phenomenon and design the instrument transformers in a way so that even in the event of ferroresonance there is no damage...
In this paper, modeling of STATCOM for regulate the voltage in power flow calculation is proposed. Based on power flow, the proposed technique has been presented and tested on 26-bus power system. The results proved the correctness of the proposed technique. The influence of the STATCOM on regulating voltage and decreasing power losses has also been discussed in detail.
This article discusses about the impact of new emission limits for nitrogen oxides (NOx) emissions which will be effective from 2021 for large combustion plants (LCP) in the Czech Republic and discusses about possible ways and techniques to achieve these strict emission limits.
Lever magnets, often defined s magnets with variable reluctance or open C-frame magnets, belong to significant components of automation system, heir thrust being based on the force generated upon convenient curvature of flux lines within the magnetic field gained through specific geometrical layout of the magnetic circuit. Their main advantages include a relatively high tensile force at the beginning...
High temperatures reduce the output power of photovoltaic panels. This work analyzes the influence of surfaces with different albedo indices on the temperature of the panels, from the comparison between two surfaces with different emissivity indices. A water-based reflective material composed of hollow ceramic nanometer beads was used on the installation surface of the panels, compared to the installation...
This article discusses rechargeable stations for electric vehicles. Deals with the current infrastructure, assumed progress of electro mobility, estimated amount of electric energy required for charging of electric vehicles. There are analyzed topics such as methods of charging of batteries in electric vehicles, basic concept of charging station. Also is included practical measurement on a small charging...
The paper contemplated the possibility of using the power thermobattery with special converters that operate from voltages in the tens of millivolts. Two such converters have been developed; their characteristics have been measured and documented. The only thermobattery with such a converter is able to supply low-power devices from the temperature difference of one tenth of a degree Celsius.
This paper presents comparative study between Fuzzy and Predictive controllers. They are implemented to speed control of a direct current (DC) machine, triggered by fully controlled three-phase AC-DC converter. Searching for high performance controllers, it's performed controllers' parameters optimization, through the use of the heuristic method Genetic Algorithm. It seeks to determine which of the...
This article represents a continuation of a longstanding research concerning behaviour prediction (consumption) of lighting systems collected on the constant level of illuminance depending on daylight. Due to the occurrences of differences between the prediction model and the actual long-standing lighting measurement in monitored lighting system it has been vitally important to seek the source of...
The objective of this work is to develop a model that represents the thermoelectric generation plant with the purpose of optimizing the search of the maximum power point in the thermoelectric generators. Are used converters DC-DC controlled by artificial intelligence techniques. The method consists of regulating the voltage to connect various loads as batteries, and compare the optimal control methods...
It is common in engineering to model time-dependent variables as diffusion process represented by stochastic differential equations. This is usually helpful when empirical datasets describing time evolution of variables are available. This helps in accurate estimation of parameters of the stochastic differential equation which describes the dynamic system. Additionally, it helps in characterization...
Most of the electricity produced in nuclear power plants comes from pressurized water nuclear reactors. Currently, the main fuel of pressurized water nuclear reactors is enriched uranium. The thermal energy is produced by fission of uranium 235 using slow (thermal) neutrons. Generation IV reactors are already contemplate obtaining thermal energy from the fission of uranium 238 using fast neutron....
The train velocity is needed to be known for many purposes like the train safety systems or a slip control. The train velocity is typically determined from wheelsets velocity. The wheelset velocity is different with the train velocity due to a slip velocity that is needed for a force transmission between wheels and rails. The train velocity measured by this way is the only estimation of the train...
Direct torque control (DTC) is one of the best performing strategies for induction motor control in many applications. However, this method suffers from a few disadvantages. Very important one is the presence of ripples in the torque waveform. The main reason of their presence is the inaccurate model of the motor. This paper utilizes Luenberger observer to calculate the model of the motor instead...
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