۱Driving Vacuum Circuit Breaker Using Output Current of Current Transformer
نویسنده(ها):
اطلاعات انتشار: بیست و یکمین کنفرانس بین المللی برق، سال
تعداد صفحات: ۵
When the electrical fault, such as short–circuit or overload current, happens in the middle voltage network, a current transformer detects it and the vacuum circuit breakers (VCBs) quickly open and interrupt the fault current (tripping). Recently, electromagnetic actuators are widely used as operating mechanism for the VCB. In this paper the possibility of the direct tripping of the electromagnetic actuator by the current output of the current transformer is investigated numerically. In simulation, the secondary current waveform was calculated by response surface approach. It can take into account of the saturation effect of the magnetic core due to high primary current and heavy loads of the secondary circuit. The mechanical behavior of VCB in time was also simulated coupling with the actuator motion and the operating electrical circuit. Finally tripping tests by the current transformer output with high primary current was performed.<\div>

۲Design Optimization of Current Transformers Using Robust Design Methodology
نویسنده(ها): ، ،
اطلاعات انتشار: هجدهمین کنفرانس بین المللی برق، سال
تعداد صفحات: ۱۷
In this paper a cost effective system design of current transformer (100\5 Ampere) through application of robust design methodology is proposed. The results show that with better performance, the market price of proposed current transformer can be much less than half the price of one of the famous current transformer brand in market. These results are obtained under vast environmental conditions of network frequency and temperature variations of Iran.<\div>

۳Current Transformer Transient Behavior Analysis And modeling
نویسنده(ها): ،
اطلاعات انتشار: هجدهمین کنفرانس بین المللی برق، سال
تعداد صفحات: ۱۲
In this paper current transformer transient analysis and modeling are studied. A computer program has been developed to simulate a CT core. The paper describes an iterative method to model the CT core transient behavior during a system short circuit fault. Different parameters and actors could be selected in the software and their amounts am changed to investigate their effect on the CT transient response. These results can be used to comprehend the transient behavior of the CT and make real test signals for testing protective relays based on the actual behavior of current ~formers. The effect of CT Transient and saturation on different protective schemes such as distance and breaker failure algorithm could be studied using the developed software.<\div>

۴RELIABLE DISTANCE PROTECTION ALSO WITH DISTORTED CURRENT MEASUREMENT
اطلاعات انتشار: پانزدهمین کنفرانس بین المللی برق، سال
تعداد صفحات: ۷
Distance protection must provide fast and selective fault clearance during system faults. The performance level of a distance protection device is primarily determined by its speed of operation and the accuracy of its distance measurement. Both these, criteria are however not constant, they are influenced by system and fault conditions such as for example distance to fault, arc resistance etc. and by the quality of the measured signals. In this paper, it is shown how the current transformer influences the accuracy of the distance measurement and how modern numerical distance relays respond with selfcorrecting action.<\div>

۵Finite Element Analysis of the Asymmetric Field Distribution Effect on the Operation of a Current Transformer
اطلاعات انتشار: پانزدهمین کنفرانس دانشجویی مهندسی برق ایران، سال
تعداد صفحات: ۴
Current transformers (CTs) are important in power grids because they feed the protection relays with current signals. So the accuracy of their output signals should beensured in various conditions. Different factors affect the accuracy of the CT output current. Some of them such as thestray flux produced by the adjacent bus bars current and theeccentricity of the primary conductor with respect to the CT cause the magnetic field distribution of the current transformerto be asymmetric. So they can result in the current transformer local saturation in specific conditions which can lead to theundesirable operation of the protection relays. In this paper, the operation of a typical current transformer with protection coreis analyzed in the presence of these factors. The conditions considered in this paper include the operation under the adjacent bus bar overload and when there is an eccentricity in the primary conductor with respect to the CT core. These conditions are analyzed using 2D FEM.<\div>

۶Design Modification of Rogowski Coil for Current Measurement in Low Frequency
نویسنده(ها): ،
اطلاعات انتشار: Iranian Journal of Electrical and Electronic Engineering، ششم،شماره۴، Dec ۲۰۱۰ ، سال
تعداد صفحات: ۶
The principle object of this paper is to offer a modified design of Rogowski coil based on its frequency response. The improvement of the integrator circuit for nullifying the phase difference between the waveforms of the measured–current and the corresponding terminal voltage is a further object of this investigation. This paper addresses an accurate, yet more efficient measuring and protecting device for low frequency applications. This requires verification for the simulations by physical descriptions and experimental results. These validate the superior performance of Rogowski coils over conventional current transformers. Keywords: current transformer, frequency response, integrator circuit, mutual inductance, Rogowski coil, terminal resistor
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