• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.11
• /
• pp.2089-2094
• /
• 2009

The fault current has increased due to growth of distributed generations for the large power demand in power distribution system. To solve some problem such as excess of the circuit breaker's cut-off ratings, the superconducting fault current limiter(SFCL) has been progressed. However, the operational characteristics of the relay is changed by SFCL. Therefore, the proper impedance for the SFCL should be selected to keep protective coordination with the SFCL when SFCL is introduced on the neutral line of main transformer in distribution system. In this paper, the proper normal conducting resistance was suggested to solve the problem in case of the protection coordination with SFCL.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.2090-2091
• /
• 2007

We investigated the characteristics of transformer type SFCL with neutral line. The transformer type SFCL having neutral line has achieved the simultaneous quench because the secondary winding has acted as parallel reactor. The fault current of SFCL was limited according to ratio of turn number between primary and secondary windings. Therefore, the power burden of superconducting element can be reduced by reduction of ratio of turn number between primary and secondary windings. As a result, we could expect reduction of it's volume in the transformer type SFCL.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.5
• /
• pp.54-60
• /
• 2004

With the proliferation of nonlinear loads such as commercial facilities in all of modern society high neutral harmonic currents have been observed. High neutral currents in three-phase four-wire distribution systems can cause lots of harmonic problems. The most common solution of neutral harmonic currents reduction is a zero phase sequence filter using zig-zag transformer. This paper analyzes a commercially available neutral line zero sequence currents reduction device and applies the equipment to commercial office loads for eliminating harmonics. Experimental results m compared numerically and graphically with simulation results through the use of MATLAB.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.3
• /
• pp.59-64
• /
• 2004

With the proliferation of nonlinear loads such as lighting facilities in all modern society high neutral harmonic currents have been observed. High neutral currents in three- phase four-wire distribution systems can cause lots of harmonic problems. The most common solution of neutral harmonic currents reduction is a zero phase sequence filter using zig-zag transformer. This paper analyzes a commercially available neutral line zero sequence currents reduction device and applies the equipment to lighting loads for eliminating harmonics. Experimental results are compared numerically and graphically with simulation results through the use of MATLAB.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.55 no.7
• /
• pp.290-296
• /
• 2006

If the three phases are not balanced, the current in neutral wire is not zero. Then, the induced voltage can be generated in communication line. The KEPCO's rule about unbalanced current for one step type in distribution pole is a twenty percent of phase current. But the unbalanced current for two step type in distribution pole can't decide the rule because there are many different views. This paper presents the calculation and analysis technique of neutral current in distribution poles using equivalent circuit analysis and EMTP simulation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.10
• /
• pp.1470-1474
• /
• 2013

In this paper, proper length of neutral section and neutral section system configuration is proposed to minimize accidents if ATO urban railway vehicle stops maintaining the leading vehicles in air section at regular intervals. When considering the minimum voltage sensing of power conversion unit in the urban railway vehicle, the effective length of 14,280[mm] with neutral section can be minimized damage due to high current because the urban railway vehicle is very little present chance compare neutral section with pantograph interval installed on a unit vehicle. In addition, uplift of catenary line and contact wire consider to minimize damage. The result of theoretical review, as the proposed neutral section shorter, isolated neutral section is effective than the integrated neutral section.

• Proceedings of the KSR Conference
• /
• 2003.10c
• /
• pp.541-546
• /
• 2003

The study is about a neutral section device adopted in the catenary system in connection with KNR's project to electrify the conventional Honam-Line. A neutral section device(PTFE type) adopting into catenary system accepts a train velocity of 200km/h, installed firstly in Korea electric. railway system. This study shows technologies and construction cases of the neutral section device.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.4
• /
• pp.30-36
• /
• 2015

The formulation of calculation method for electromagnetic inducing current by aerial power distribution line is established. Nearby telecommunication cables can be induced due to the leakage of neutral current because the neutral line of power distribution is grounded at every 50 m distance. By the existing calculation method, the neutral line is regarded as a shielding conductor and the neutral current roles as an inducing current. So the error range to real measurement value is largely extended because the changing effect of leakage current flowing in the ground is not reflected. The leakage current returns to the power substation through the ground and is cumulated as being closer to the substation. When this practical inducing mechanism is applied, the deviation rate of calculation can be drastically reduced within about 100 % range compared to 1000 % of the exsiting method.

• Journal of Korean Physical Therapy Science
• /
• v.3 no.4
• /
• pp.139-145
• /
• 1996

This study was carried out to investigate the scapular rhythm of normal persons. 16 persons was no disease, injury and after-effect in period for July 1, 1996 to July 14, 1996. The statistical measures were performed by SPSS/PC t-test for classification. The result of this study were as follow : 1. There was a significant difference between the body median line and scapular superior angle from the mean distance in 83.4 mm of male and 86.0 mm of female to shoulder neutral position(p<0.05). 2. The mean distance of body median line between scapular inferior angle was 97.9 mm of male and 92.0 mm of female to shoulder neutral position. 3. There was a significant difference between the body median line and scapular inferior angle from the mean distance with male and female to shoulder abduction $90^{\circ}$ position(p<0.05). 4. The mean angle of body median line between scapular angle was $6.4^{\circ}$ of male and $4.4^{\circ}$ of female with shoulder neutral position. 5. The mean ratio of scapular rhythm was 5.6 : 1 in shoulder abduction of $90^{\circ}$ and 5.1 : 1 in shoulder abduction of 180.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.3
• /
• pp.479-485
• /
• 2011

In 22.9kV underground distribution system, power cables are provided with multiple-point ground in which each neutral line of the distribution cable(A, B, C phases) and three-wire common grounded at every connecting section. But in such grounding methods, circulating current flows between the neutral wire and grounding wire. And power loss due to circulating current also occurs in all conductors. Therefore it is getting necessary reducing circulating current in underground distribution system. This paper presents improved grounding method to overcome such problems. The proposed grounding method eliminates circulating current in the neutral line effectively and is verified that there is no electrical problem or any ineffectiveness of operating protection systems. These analyses are carried out by EMTP/ATPDraw to compare each grounding methods in steady and transient state. This grounding method suggested in this paper can be applied on real distribution system after field tests considering elimination of circulating current was implemented.