Search results for "limiter"
showing 10 items of 25 documents
Currents Distribution During a Fault in an MV Network: Methods and Measurements
2016
When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighboring substations. In this paper the problem of fault current distribution is introduced, the tes…
Arc Fault Detection Method Based on CZT Low-Frequency Harmonic Current Analysis
2017
This paper presents a method for the detection of series arc faults in electrical circuits, which has been developed starting from an experimental characterization of the arc fault phenomenon and an arcing current study in several test conditions. Starting from this, the authors have found that is it possible to suitably detect arc faults by means of a high-resolution low-frequency harmonic analysis of current signal, based on chirp zeta transform, and a proper set of indicators. The proposed method effectiveness is shown by means of experimental tests, which were carried in both arcing and nonarcing conditions and in the presence of different loads, chosen according to the UL 1699 standard…
Circuit proposals for high-voltage latching current limiters
2019
This work discusses some ideas to adapt existing low voltage Latching Current Limiter (LCL) circuits to high voltage operation to provide a basis for future designs. Component selection, driver and ancillary power supply are key issues discussed which eventually provides a high-voltage LCL proposal. Experimental validation of two different prototypes (380Vdc and 1kVdc) is included as well as some digital techniques to enhance LCL capabilities.
FAST EDGE-FILTERED IMAGE UPSAMPLING.
2011
We present a novel edge preserved interpolation scheme for fast upsampling of natural images. The proposed piecewise hyperbolic operator uses a slope-limiter function that conveniently lends itself to higher-order approximations and is responsible for restricting spatial oscillations arising due to the edges and sharp details in the image. As a consequence the upsampled image not only exhibits enhanced edges, and discontinuities across boundaries, but also preserves smoothly varying features in images. Experimental results show an improvement in the PSNR compared to typical cubic, and spline-based interpolation approaches.
Nuclear Analysis of an ITER Blanket Module
2013
ITER blanket system is the reactor’s plasma-facing component, it is mainly devoted to provide the thermal and nuclear shielding of the Vacuum Vessel and external ITER components, being intended also to act as plasma limiter. It consists of 440 individual modules which are located in the inboard, upper and outboard regions of the reactor. In this paper attention has been focused on to a single outboard blanket module located in the equatorial zone, whose nuclear response under irradiation has been investigated following a numerical approach based on the Monte Carlo method and adopting the MCNP5 code. The main features of this blanket module nuclear behaviour have been determined, paying part…
Current and Voltage Behaviour During a Fault in a HV/MV System: Methods and Measurements
2015
When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighbouring substations. In this paper the problem of fault current distribution is introduced, the te…
A fiber-based limiter at 170 Gbit/s for all-optical regeneration
2009
We report the numerical and experimental studies of a spectrally filtered fiber-based optical limiter at 170 Gbit/s. The device, including less than 1 km-long of highly nonlinear optical fiber and a 3 nm-width filter, exhibits good performance at an average input power of 14.5 dBm. No power penalty has been observed and a strong robustness against optical noise has been demonstrated.
Analysis of Torque Developed in Axial Flux, Single-Phase Brushless DC Motor With Salient-Pole Stator
2004
An analysis of the torque developed by a single-phase disc brushless permanent magnet motor with salient-pole stator is presented. The machine represents a new family of brushless disc motors with the starting torque issue appearing to be most challenging. To produce a starting torque, the permanent magnets on one of the rotor discs are distributed nonuniformly. However, this significantly distorts a shape of the cogging torque versus rotational angle characteristic which, in turn, affects a waveform of the overall torque. A three-dimensional (3-D) finite-element model is used for the purpose of determining of angular variations of the torque developed by the motor. To find how the torque v…
Performance Improvement of Grid-Integrated Doubly Fed Induction Generator under Asymmetrical and Symmetrical Faults
2023
The doubly fed induction generator (DFIG)-based wind energy conversion system (WECS) suffers from voltage and frequency fluctuations due to the stochastic nature of wind speed as well as nonlinear loads. Moreover, the high penetration of wind energy into the power grid is a challenge for its smooth operation. Hence, symmetrical faults are most intense, inflicting the stator winding to low voltage, disturbing the low-voltage ride-through (LVRT) functionality of a DFIG. The vector control strategy with proportional–integral (PI) controllers was used to control rotor-side converter (RSC) and grid-side converter (GSC) parameters. During a symmetrical fault, however, a series grid-side converter…
Measuring the isotope effect on the gross beryllium erosion in JET
2022
Abstract The isotope effect, hydrogen (H) versus deuterium (D), on the gross beryllium (Be) erosion yield has been measured in ohmic limiter plasmas in JET tokamak by spectroscopic means. A simplified method to extract the effective sputtering yield from the quotient of the radiances of the D α or D γ and the Be II lines at 527 nm was applied. A clear isotope effect has been found, the erosion yield of D being about a factor of 2 larger compared to H in the whole explored plasma density range. This is in agreement with physical sputtering data obtained with H+ and D+ ion beams and also with material surface computer simulations. The already published contribution of chemically assisted phys…