Method of controlling Corona effects and breakdown voltage of small air gaps stressed by impulse voltages (original) (raw)
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Optimization and prediction of dielectric behavior of small air gaps stressed by DC voltages
2014
The present paper aims to the investigation of the methods used to optimize and predict via simulation the values of the Corona onset voltage, the Corona current and the Breakdown voltage in small rod-plate air gaps when stressed by dc voltage. The main factors which influence greatly the distribution of the electric field in the gap, and hence the above values are the geometry and the selection of grounding and charging of the electrodes, (ground effect), the polarity effect, the gap length, and the Corona effects appearing prior to breakdown. Combining theoretical, simulation and experimental work, it is resulted that: a) The electrode chosen to be ground, strongly influences the distribution of the field and the Corona effects and hence the values of the Corona onset, the Corona current and breakdown voltage. b) Minimum values of the Corona onset voltage and maximum values of the Corona current and the breakdown voltage were defined in relation to the geometry of the gap and in connection to the effects of grounding, polarity and Corona current.
Eurocon 2013, 2013
The present paper aims to the investigation of the methods used to minimize or maximize the values of the Corona onset and Breakdown voltage in small rod-plate air gaps when stressed by dc or impulse voltages. The geometry and the selection of grounding and charging of the electrodes, (ground effect), the gap length, the existence of barrier in the gap (barrier effect), and the Corona effects appearing in the gap prior to the breakdown are the main factors, which influence greatly the distribution of the electric field in the gap, and hence the above values. Combining theoretical, simulation and experimental work, it is resulted that: a) The electrode chosen to be ground, strongly influences the distribution of the field and the Corona effects and hence the values of the Corona onset and breakdown voltage. When the rod is grounded and the plate is negatively charged the value of Corona onset voltage is higher, the corona effects are less intense and dc breakdown voltage, without Corona, is higher. When the plate is grounded and the rod negatively charged the value of the Corona onset voltage is lower, the corona effects are more intense and hence the dc breakdown voltage is higher. b) A dielectric barrier, when placed in specific positions in the gap, decreases the Corona effects and raises the breakdown dc voltage. c) In air gaps stressed by impulse voltages the results are very different. The corona onset and the breakdown voltage are maximum when the rod is grounded and positive leading to more intense Corona effects.
Investigation the polarity effect and the voltage breakdown in small air gaps
2020
In this paper, a new method of the polarity result in link to the corona current and also the ground effect in small rod-plate and rod-rod air voids is presented. The impact of the polarity of the used voltage to the corona start voltage or the breakdown voltage of tiny rod-plate and rod-rod air gaps is examined. Two kinds of anode pole has actually been researched in this paper with different ranges of voltage and air space ranges. The impact of the grounding is one of the electrode to the area circulation, and also subsequently to the corona onset and the breakdown voltage of little air voids is likewise investigated by speculative experimental analysis
Optimization of Corona Effects in Small Air Gaps Stressed by DC Voltages
2012 Sixth UKSim/AMSS European Symposium on Computer Modeling and Simulation, 2012
In the present paper methods of minimizing or maximizing the values of the Corona onset voltage and the Corona current in small rod-plate air gaps are investigated. The geometry and the way of grounding and charging the electrodes, (Ground Effect), the gap length, the existence of barrier in the gap (Barrier Effect), and the conditions of the air in the gap, are some factors, which influence greatly the distribution of the electric field in the gap, and hence the above values. Combining experimental and simulation-theoretical work, it is resulted that: a) the electrode chosen to be ground, strongly influences the distribution of the field and hence the Corona onset voltage and the corona current in rod-plate air gaps. When the rod is grounded the value of the corona onset voltage is higher and the corona current is significantly smaller. b) A dielectric barrier, when placed in specific positions in the gap, increases the Corona onset voltage to a maximum value, and annihilates the Corona Current.
2013
In the present paper methods of controlling Corona and breakdown in small rod-plate air gaps are investigated. Combining experimental and simulation-theoretical work, it is resulted that when the rod's diameter is bigger, the gap length larger and the rod is grounded the field is less inhomogeneous. Therefore the value of the dc breakdown voltage without Corona is higher. If Corona occurs then the values of the Corona onset voltage are higher, and the corona effects are not intense. The Corona effects, lead to a rise of the value of the dc breakdown voltage especially when the rod is negatively charged. Moreover an insulated thin barrier, when positioned near the rod increases the breakdown dc voltage to a maximum value, and minimizes the Corona effects. Especially for gaps stressed by impulse voltage the Corona effects, appearing with the form of electric current pulses, are influenced by the same factors with a different way. The values of the breakdown voltage in contrast to what happens with dc voltage are higher when the Corona effects are weaker, depending on the influence of the field's inhomogenity (geometry and effect of grounding). It is also resulted that a resistor connected in series with the gap decreases its maximum charging voltage and increases the value of the breakdown voltage.
One of the most determinant factors of the dielelectric strength of the air gaps is the field strength distribution in the gap. The corona space charges in the gap influence also the distribution of the field strongly and hence the breakdown voltage of the gap. In the present paper the arrangements rod-plate air gaps with or without a barrier for the two different cases with the rod or the plate grounded are experimentally investigated and analyzed with the aid of special simulation software, using the Finite Element Method. Values of the field strength in the gap, while stressed by the breakdown voltage are recorded and analyzed. The results show that the distribution of the field along the axis of the gap is strongly affected by the geometry of the gap, and especially by the grounded electrode (Ground Effect). The value of the breakdown voltage depends on the maximum value of the field strength in the gap as well as the value of the corona leakage current through the gap. A charge...
Modeling and analysis of electric field distribution in air gaps, stressed by breakdown voltages
WSEAS Transactions on Systems, 2004
This paper investigates the Modeling and Analysis of the electric field distribution in air gaps, stressed by the breakdown voltages, under different geometries and arrangements, with Finite Element Method. The influence on the electric field distribution, caused by the insertion of a dielectric insulated plate, called Barrier, between the electrodes, is presented. The average, the maximum and the minimum value of the field strength along the gap axis, when the breakdown voltage stresses the air gap are recorded and analyzed. The results show that the distribution of the field in the gap axis is strongly affected by the geometry and the arrangement of the gap. The average and the minimum value of the field strength along the gap axis, decreases when the gap length increases, while the maximum value of the field strength or the Field Factor in the gap, functions differently, strongly depending on the gap geometry. In a non-uniform field arrangement, such as rod -plane, a charged dielectric plate, placed between the electrodes of the air gap, influences the distribution of the electric field. The simulation results are compared with relative results of referent work.
Investigation of the Ground Effect in connection to the Barrier Effect in rod-plate air gaps
Two of the most determinant factors of the dielelectric strength of the air gaps are the field strength distribution and the corona space charges in the gap. In the present paper the Ground Effect in the air gaps that is observed due to the electrode chosen to be grounded is investigated. Values of the field strength in the gap, while stressed by the breakdown voltage are recorded and analyzed for the two different arrangements with the rod or the plate grounded. The results show that the distribution of the field along the axis of the gap is strongly affected by the geometry of the gap, and especially by the grounded electrode. The Ground Effect also affects the breakdown voltage of the gaps with or without a barrier. The values of the breakdown voltage depend on the maximum value of the field strength (usually on the rod) and the values of the field strength on the barrier, as well as the values of the corona leakage current through the gaps.
In the present paper the Ground Effect of small rod–plate air gaps, which is observed due to the grounding of one of the electrodes, is investigated. Values of the field strength in the gap are recorded and analyzed for the two different arrangements, with the rod or the plate grounded. The distribution of the field along the axis of the gap is strongly affected by the geometry of the gap, and especially by the electrode chosen to be grounded. The Ground Effect also affects the breakdown voltage of the rod-plate air gaps but in a quite different way than the Polarity Effect does. The values of the breakdown voltage depend on the maximum value of the field strength in the gap, and the corona leakage current through the gap. According to the Polarity Effect the breakdown voltage is considerably higher in the arrangement with negative polarity on the rod because of the intensive corona effects. According to the Ground Effect the breakdown voltage is higher in the arrangement with the r...