• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.8
• /
• pp.49-54
• /
• 2015

Molded Circucit Breaker(MCCB) is a most widely used device to protect loads from the over-current in low power level distribution system. When the MCCB interrupts the over-current, the arc discharge occurred between fixed contact and moving contact to create hot gas. By the Lorentz force due to arc current, the occurred arc is bent to the grids. The grids extend and cool and divide it for arc extinguish. In the majority cases, the MCCB protects loads by interrupting the over-current successfully but in some cases the re-ignition is occurred by hot-gas created during process of interruption. The re-ignition arises when the recovery voltage(RV) is more higher than the recovery strength between contacts and it leads to interruption fault. Therefore to find out the dielectric recovery characteristics of protecting device has a great importance for preventing interruption fault. In this paper, we studies measurement method of the dielectric recovery characteristics considering inherent attribute of the MCCB. To measure the dielectric recovery characteristic of MCCB, we makes an experiment circuit for applying the over-current and the randomly recovery voltage. The measurement methode to find out the dielectric recovery voltage of the MCCB was established and the result was based on experiment results.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.11
• /
• pp.555-563
• /
• 2006

This paper presents the measured radiation intensity of high-pressure and large-current arc with the current. In order to measure the radiation intensity of large-current arc, a model circuit breaker was specially designed and manufactured and the method using an astronomical telescope was utilized after various measuring methods were investigated. A trigger system was designed and fabricated to coincide the time of desired current with the exposure time of 1ms of the spectroscope. A high-speed camera was used to investigate the shape and behavior of the arc and the captured results have been used to calculate the radiation energy. The calculated arc temperature with Boltzmann plot method using the measured radiation intensity have $18,000{\sim}27,000K$ to the current $4kA{\sim}15kA$. And also, using the calculated arc temperature and the captured arc shape the radiation energy of the current $5kA{\sim}15kA$ were calculated with $8{\times}10^5{\sim}4.0{\times}10^6W/m$ respectively.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.12
• /
• pp.1803-1808
• /
• 2013

To maintain contact between catenary and pantograph copper is important in order to transmit power smoothly on Current collection system. But, Arc discharge with strong light is generated because of contact loss. Therefore, Arc discharge detection is important measurement factor judging performance of current collection system. In this paper, It is described to results of arc discharge applying UV detection technology using arc generator. And Arc discharge was detected using the most commonly used processing catenary and rigid catenary and pantograph copper of electric rolling stock for securing arc detection instrument reliability. Results of contact loss detection instrument in this paper will be used for maintenance of current collection quality and system.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1495-1496
• /
• 2008

The Ceramic Metal Halide lamp is different from optical characteristic on shapes of arc-tube and driving method of ballast. In this paper, we measured optical characteristics of the Ceramic Metal Halide lamp that uses arc tubes which are spherical and cylindrical shapes, and analyzed the Ceramic Metal Halide lamp connecting ballast that is electronic and magnetic types through the lamp measurement system that is given for stabilization period of fifteen minutes. In result, the arc-tube of spherical shape is more improvement in the optical properties than the arc tube of cylindrical shape, moreover, the electronic ballast is more efficient than the optical properties of the magnetic ballast.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.03b
• /
• pp.24-24
• /
• 2010

In this paper, we analyzed the frequency spectrum of electromagnetic waves which is generated by series arc discharges to develop a condition monitoring technique in a closed-distribution board. We fabricated an arc generator specified in UL1699 to simulate series arc discharge. The experiment was carried out in an electromagnetic shielding room, and the measurement system consists of a Ultra Log Antenna and a EMI Test Receiver. The results showed that the frequency spectrum during series arc discharges was distributed in ranges of 30~500 [MHz], and the peak values were existed at 40 [Mhz] and 80 [MHz].

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.41-45
• /
• 2010

In this paper, we analyzed the frequency spectrum of radiated electromagnetic waves generated by series arc- and corona- discharges as a basic study to develop an online diagnostic technique for power facilities installed inside switchboards. To simulate corona and series arc discharges, an arc generator specified in UL1699 and a corona generator were fabricated. The experiment was carried out in an electromagnetic shielding room, and the measurement system consists of an Ultra Log Antenna and an EMI Test Receiver. The frequency spectrum exists in ranges from 30 to 500 [MHz] for series arc discharge and 30 [MHz] to 2 [GHz] depending on defects for corona discharge. The peak frequency of series arc discharge and corona were 40 [MHz], 80 [MHz] and 35 [MHz]~160 [MHz], respectively.

• Journal of Welding and Joining
• /
• v.28 no.6
• /
• pp.28-34
• /
• 2010

This paper was described on investigation to prevent porosity in high speed MIG Welding of Al 6082-T6. Porosity measurement was carried out by using image analysis of micrographs with the help of an analysis software. The main parameter was arc length and torch progressive angle. The porosity ratio was increased as arc length was increased. The arc length was increased depending upon the output voltage. By proper selection of pulse waveform parameter, the stable arc of one pulse one drop was generated. The porosity ratio of optimum condition in one pulse one drop was lower than high voltage condition. When torch progressive angle was an angle of advance $10^{\circ}$, porosity ratio was minium.

• Journal of Astronomy and Space Sciences
• /
• v.32 no.3
• /
• pp.189-200
• /
• 2015

In this study, we present the results of orbit determination (OD) using satellite laser ranging (SLR) data for the Science and Technology Satellite (STSAT)-2C by a short-arc analysis. For SLR data processing, the NASA/GSFC GEODYN II software with one year (2013/04 - 2014/04) of normal point observations is used. As there is only an extremely small quantity of SLR observations of STSAT-2C and they are sparsely distribution, the selection of the arc length and the estimation intervals for the atmospheric drag coefficients and the empirical acceleration parameters was made on an arc-to-arc basis. For orbit quality assessment, the post-fit residuals of each short-arc and orbit overlaps of arcs are investigated. The OD results show that the weighted root mean square post-fit residuals of short-arcs are less than 1 cm, and the average 1-day orbit overlaps are superior to 50/600/900 m for the radial/cross-track/along-track components. These results demonstrate that OD for STSAT-2C was successfully achieved with cm-level range precision. However its orbit quality did not reach the same level due to the availability of few and sparse measurement conditions. From a mission analysis viewpoint, obtaining the results of OD for STSAT-2C is significant for generating enhanced orbit predictions for more frequent tracking.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.2113-2115
• /
• 2000

It is necessary to install the arc generation facility in order to obtain the important technology for the design of breakers and switches, and for the improvement of their performance and reliability. With this facility, it is possible, to study the characteristics of Arc in air/gas/vacuum insulation environment. The facility briefly consists of capacitor bank which can charge enormous energy, an air-core reactor, experimental arc-chamber, and several measurement equipments. This facility can simulates the arc phenomena in breakers and switches by means of generating high currents. In order to study the arc phenomena in SF6 gas and vacuum and to test the quenching performance of the extinguishing chambers which are developing. we made experimental $SF_6$gas/vacuum chambers and measured several parameter's of chambers. And besides we visualized arc ignition and arc movement by means of high speed camera.

• Journal of Welding and Joining
• /
• v.19 no.4
• /
• pp.413-422
• /
• 2001

In this study. two-dimensional heat flow and residual stress in arc brazing to join the pipe and plate structure were analyzed by using a commercialized FEM package. Advantages offered by arc brazing are that strong joints can be produced with lower heat input than that of previous gas metal arc welding and narrower heat affected zone can usually be obtained than that in the case of torch brazing. To investigate the effects of process variables and minimize the thermal effects on the structure, this study presents a method for analyzing the heat flow and residual stress in arc brazing process according to variables such as traveling speed, torch angle and position. The simulation results were compared with the experimental ones to verify the numerical analysis method. The experiments include the measurement of HAZ size from the section of joints and residual stresses by using strain gages named 'section method'. A comparatively good agreement between the results of numerical analysis and experimental ones could be obtained in both of the temperature distribution and residual stress of the brazed structure. Using the proposed numerical analysis method, the process parameters were evaluated to get proper arc brazing conditions.