• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.05a
• /
• pp.78-81
• /
• 2000

Metal oxide surge arrester were developed in the late 1970s, and were immediately adopted as significant breakthrough in over voltage protection of power system. Work was continued throughout the world on the design, development and application of metal oxide surge arrester. This paper describes the evaluating test and results of practical use for analyzing the performance of gapless metal oxide surge arresters under various type test. In the result, ZnO element exhibited badness rate of 6.95 percent.

• Proceedings of the KIEE Conference
• /
• 2004.11a
• /
• pp.26-28
• /
• 2004

The primary role of ZnO arresters is to protect transmission and distribution equipments against lightning surges. The extremely nonlinear V-I characteristics of the ZnO arrester obviates the need for isolation gaps and consequently it is continuously connected to line voltage. For this reason, ZnO arresters are degraded with time in actual power systems. In this work, the characteristics of the luminous events caused between the ZnO block and electrodes according to the electrode area were investigated. As a result, the luminous events were effected by electrode area and the longer electrode areas were increased, the more luminous events were decreased. Also the reduction of luminous events was fumed up to the degraded ZnO arrester block.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1460-1462
• /
• 2003

XLPE compound have used for insulation of 22.9 [kV] power cable. XLPE compound is aged for use long time in distribution line. The cause of aging is water tree is happening and growth. Accelerated water tree test method are Accelerated volatge method and high frequency method. In this paper, high frequency accelerated water tree was performed. And the result was analysed AC breakdown voltage and size and number of water trees.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.153-156
• /
• 2000

To reduce the maintenance expense, and the possibility of electric outage and accident, we should optimize the outdoor insulation system. And for the optimization, accurate measurement for the degree of contamination with climatic conditions, such as wind, rain, and drought, should be carried. However the classical measuring method, brush wiping, has some problems in the aspect of man power, reliability, and expense. In this paper, we propose two type apparatus, which could detect the degree of contamination on insulators in outdoor insulation system, such as transmission and distribution line insulator and bushing. One use the leakage current, and the other use the oscillating frequency to check the degree of contamination. To avoid the oxidation of electrode AC source, and the low degree of contamination was applied. From the result of this investigation we could get the good relationship between the degree of contamination and the leakage current and oscillating frequency

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.2
• /
• pp.459-467
• /
• 2017

An urban railway power substation consists of three thyristor dual converters. Two converters are connected to up and down trolley line to supply the electric energy or feed the regenerative energy back to the distribution. When the two converters break down, the remaining converter is used in an emergency. One thyristor dual converter system (TDCS) manages the energy of two or three railway stations. If the TDCS fails, the trains stop operating. To solve the problem, this paper proposes the three parallel operation control algorithm of thyristor dual converter system using the emergency converter. The broken TDCS can be replaced by the emergency converter in other TDCS. The effectiveness of this proposed control is verified by simulation.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.4
• /
• pp.444-450
• /
• 2008

There are several ways to bond to building grounding systems for reducing GPR(ground potential rise) and EMI resulting from power system faults or lightning stroke to building. In order to verify effective bonding practice, the GPR and voltage of equipment due to the direct stroke to building are calculated with ATP-EMTP model for transformer, transmission line and MOV(Metal oxide varistor). The simulated model shows a satisfactory accuracy compared with experimental result for the $8/20{\mu}s$ simulated current pulse. It is observed that separate grounding can cause dangerous voltage to the building equipment and the performance of surge protective device can improve when it is installed to the protected equipment in distance as short as possible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.07a
• /
• pp.687-690
• /
• 2000

This paper provides the result of the analysis of the lightening arresters which were disconnected from the power line due to the overvoltage having high current. The effect of thermal runaway on the microstructures of lightening arrester's block was intensively investigated. The chance of the microstructures of the blocks was limited only on the breakdown paths and near them. Also even though a disconnector was disconnected from the arrester, some of the lightening arrester were showed normal characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.216-219
• /
• 2003

This paper presents the analyzing method for surface temperature distribution of a cast-resin transformer. For the study, the surface temperature of the transformer winding was measured and analyzed by a infrared thermography system. Alternating voltages were applied to simulate deterioration of the specimen transformer, and the hot-spot on the transformer surface was measured to analyze the condition for the winding. The hot line condition measured to the changes in surface temperature using infrared thermography camera and was set up the based of diagnostic method of the electric power apparatus. The results ould show the possibility of remote diagnosis using internet.

• Proceedings of the KIPE Conference
• /
• 2018.11a
• /
• pp.9-11
• /
• 2018

This paper studies on the development of an electric fire prevention system with the detection and alarm in case of parallel arc fault occurrence in low voltage distribution lines. The proposed detector has the characteristics of high speed operation responsibility and superior system reliability from composition using a large number of semiconductor devices. The line voltage is always feedback, and when an arc or a spark occurs, these are detected by the microcomputer. In addition, we design and develop algorithms using high speed and high precision microcomputer. A new conceptual control technique is adopted that RCD cuts-off by forming a forced short circuit between the phase voltage and ground in the event of an electrical accident. Some experimental tests of the proposed system also confirm practicality and the validity of the analytical results.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.43.3-43.3
• /
• 2019

A coronal mass ejection (CME) mass is generally estimated by the total brightness measured from white-light coronagraph observations. The total brightness are determined from the integration of the Thomson scattering by free electrons of solar corona along the line of sight. It is difficult to estimate the masses of halo CMEs due to the projection effect. To solve this issue, we construct a synthetic halo CME with a power-law density distribution (ρ = ρ₀r^-3) based on a full ice-cream cone model using SOHO/LASCO C3 observations. Then we compute a conversion factor from observed CME mass to CME mass for each CME. The final CME mass is determined as their average value of several CME masses above 10 solar radii. Our preliminary analysis for six CMEs show that their CME mass are well determined within the mean absolute relative error in the range of 4 to 15 %.