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In stable electrical networks, such as the German one, the service of uninterruptible power supply (UPS) systems is only rarely called. Consequently the battery lifetime in this application is mostly restricted by calendar aging. The concept of multi-use describes here the delivery of additional services with a UPS during stable grid operation. The overall goal is to allocate the battery capacity...
The electrical resistivity (ρ) of Yb doped BaTiO3 ceramics in function of temperature is investigated in this article. The concentrations of additive in the BaTiO3 doped samples were ranged from 0.01 to 1.0 at % Yb. The conventional solid state reaction is used for preparation of initial samples. The samples are sintered at 1320° and 1380°C in air atmosphere for 4 hours. The electrical resistivity...
The paper presents an original numerical-analytical method of fault location and the calculation of transverse resistance of a fault in a damaged medium voltage cable. The method is based on the measurement of input impedances for two different frequencies at one end of the cable with an open state at its other end. The proposed method was compared with the reflectometry. The effectiveness of the...
SAW sensors offer a mechanical motion in MHz to GHz range and can be immune to effects from boundary loss through the bulk and edges. SAW based gyroscopes have been implemented by added masses which impose an effect on wave prorogation fronts through the Coriolis force. A key challenge in implementing SAW based gyroscopes is to improve the sensitivity owing to small forces and SAW signals. significant...
Frequency Response Analysis (FRA) has been used as a comparative diagnosis method to explore mechanical defects in transformer. FRA is quite sensitive method and it can be influenced by different factors in transformer simply; however, this sensitivity will make it superior rather than other transformer winding deformation diagnosis techniques. This study has concentrated on tap-changer position influence...
The concept of the multi-frequency conditioning system of the individual inductive loop sensor signal, with the separation of impedance components was presented in the hereby paper. Simulation investigations concerning dynamic states in the system excited by a step change of the sensor impedance parameters, were performed. The system behaviour in the presence of disturbances — induced in the sensor...
Safe operation of electrical power network relies on healthy electrical insulation of all of its components. In general, the condition of insulation is unknown and appropriate periodic electrical testing is required to detect potential deterioration and avoid catastrophic failure of the given system.
This paper focuses to the problematic of thin film metal layers. The samples prepared by vacuum evaporation of thin film meander-shaped aluminium layers were analysed. Electrical resistance and thickness of layer were included in the measured parameters. We evaluated these parameters in dependence of the volume of the source material, i.e., an aluminium wire. We observed a certain variance in measured...
Due to the rising electrification, there is a need for innovative charging technologies to keep pace with technological progress and tethered charging. The electrical performance of wireless power transfer (WPT) systems is one crucial point in charging electric vehicles. The resonance frequency respectively the switching frequency of the converter has a large impact on system behavior. Due to component...
The improvement of the coil quality factor results to a higher efficiency for wireless power transfer(WPT) system[1–3]. Additionally, adding a suitable magnetic core into the coil can effectively enhance the mutual inductance and improve the efficiency of WPT system[4–7]. The high frequency current is un-uniform in the wire due to the external magnetic field. As a result, the conductive area of the...
The impact of converter-based loads on the power system is evaluated based on stability studies. This requires adequate load models. This paper deals with a time-domain model of an electric vehicle battery charger with grid support functionality (so-called controllable load). The dynamic properties of the components of a unidirectional 1,2 kW battery charger with input diode rectifier are discussed...
In this paper, a GaN HEMT class-E power amplifier (PA) has been designed for efficiently operating under variable load resistance at the 750 MHz frequency band. The desired zero voltage switching (ZVS) of the device can be approximated for a wide range of resistive loads, by means of a simple inductive impedance inverter, derived from [1]. The load-pull contours, obtained from simulations, allowed...
Microstrip antennas are highly resonant structures and, for simple patch configurations, the bandwidths of each mode is quite small. As an antenna, their most useful mode is the TM11 mode that radiates in the broadside direction with a good gain. All other modes, TMnm, radiate conical beams with a null in the broadside and have a pattern peak that moves towards the endfire direction by increasing...
Wound aluminum foils are traditionally known to be used for the construction of capacitors and with some difference in the arrangement for the construction of foil wound inductors. It is further known that a specific connection of the supply terminals to the ends of the aluminum foils yields capacitance and inductance at the same time. Wound aluminum foils comprising inductance and capacitance in...
This paper proposes a standstill test method for the determination of electrical parameters of permanent magnet synchronous machine (PMSM) drive system fed by a conventional three-leg inverter. In order to estimate the equivalent total circuit resistance, a self-cancellation method is proposed to eliminate the influence of inverter nonlinearity on the calculation. With the identified equivalent total...
High voltage transmission line fault location algorithm without synchronization, which does not require sampling synchronization, reduces cost and has a higher practical engineering value. But the algorithm still needs to be improved in the false root identification of ranging equation, this paper makes a further research on this issue. Firstly, the false root problem of fault location algorithm without...
This paper presents a simple method for determining the coefficients of thermal expansion (CTEs) of micro-machined polysilicon thin films. The structure is composed of the clamped-clamped beam and heated by applying direct current between two anchors. Based on the electrothermal properties of the test structure and the resonance frequency approach, an analytical model and an extracting method for...
The article explains the ways of reduction of error component of sensor communication lines capacity in using a frequency-independent dipole, an inverter, an analogue adder and measuring circuit pulse power.
Cables play an important role in many industrial systems, from power transmission to data communication. Wired connections are often operated under severe conditions and may be subject to damages or undergo accelerated aging. In order to ensure safe and cost-efficient operations, as well as a high level of performance, efficient tools are needed to assess and monitor the condition of cables. Hard-fault...
The condition monitoring and diagnosis of insulation system of wind turbine generator (WTG) has become more and more important in recent years. Previous studies have shown that the partial discharge (PD) signals in the inter-turn insulation under induced impulse voltage may probably reflect the information of insulation condition. In this paper, a new type of non-contact current sensor on the basis...
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