• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.60-67
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• 2006

This paper presents the protection effect of surge protective devices(SPDs) according to the conditions of installations. To propose the effective protection measures of information and communication equipments against lightning surges, actual-sized experiments in relation to the protection effects on the positions of installations of SPDs, the length of branch circuit, the wiring methods, and the materials of conduit, were conducted. The effective method of protecting information and communication equipments from lightning surges is to install SPDs in the vicinity of input terminals of each electronic equipments to be protected. The wiring method of connecting an SPD minimizing the length of leads is desirable when point-to-point wiring is to be used.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.9
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• pp.52-59
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• 2014

The aims of this paper are to characterize the transient overvoltages(TOVs) and to evaluate the risk occurring at 22.9kV consumer's substation. The measurements of lightning- and switching-caused TOVs were made during Mar. 2013 and Feb. 2014. As a consequence, 47 events of TOVs were recorded and 4 of them were higher than the input voltage envelope(IVE) of the information technology industry council(ITI) curve. The measured TOVs are characterized by longer front times and longer durations compared to the $1.2/50{\mu}s$ standard impulse voltage waveform, and some of them represent bipolar waves with lower oscillation frequencies. It suggests that the test of non-standard impulse voltage waveforms is needed for effective risk assessments of power apparatus. Lightning- and switching-caused TOVs exceeding IVE of ITI curve are induced at the secondary of 22.9kV potential transformer(PT). We may, therefore, conclude that the surge protection devices should be applied at the secondary of PT and the surge absorbers should be installed at the primary of VCB or PT. The results presented in this paper could be useful to design the reasonable insulation coordination for 22.9kV consumer's substation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.490-494
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• 2009

In this paper, how the temperature of a varistor changes when $10/350{\mu}s$ surge currents and/or DC leakage currents are applied on it, respectively, are investigated. The temperature change in varistor is related with injection energy and leakage current. which is the integration of power in time. By the surge current test, we found that the temperature jump is proportional to the level of surge current with slant 52.535 and has no relation with the ambient temperature. And by the DC leakage current test, the difference in temperatures between varistor and ambient is proportional to the magnitude of leakage current. The slope of measured line(the temperature difference vs. the leakage current) shows alteration around $100{\mu}A$. The varistors can not be used more than $100{\mu}A$ region any more. From the above experimental results, we can conclude that data of the surge current test and also those of DC leakage current test can predict the performance of varistors of which the surge protective devices are made.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.265-269
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• 2005

Surge protective devices can be divided into three categories based on the circuit assembly: a parallel circuit type that considers the surge current amount within the device, a series circuit type that considers the voltage and single circuit type that uses a single element. However, when assembling SPDs, there are many things including function and safety to be taken into consideration because they are directly related to the performance and safety of the device. In this paper, we executed an experimental comparative study of performance and thermal stability of each SPD type using lightning surge generator and thermal image camera.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1754-1756
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• 2002

This paper deals with an effective installation method of lightning protective devices for information and communication facilities. Due to the potential difference between grounding of the AC power lines and communication lines, the equipments connected to the communication lines are easily damaged by lightning surges. So we have examined the behaviors of surge protective devices against lightning surges from the AC power lines and signal lines, and the coordination effects of SPD installation method were investigated. As a result, it was confirmed that the bypass arrester method and common grounding method were very effected.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.94-99
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• 2003

A strong need to improve the quality of electric power is increased because of increasing use of the sensitive and small-sized electronic devices. The transient overvoltages on low-voltage AC power distribution systems are induced by direct or indirect lightning return strokes, and they can cause damage and/or malfunction of the utility systems for home automation, office automation and factory automation as well as medical equipment. The behaviors of lightning overvoltages transferred through the transformer to the low voltage AC power distribution systems were experimentally investigated using a Marx generator. The surge voltages in low-voltage ac power systems are rarely limited by the application of the surge arrester to the primary side of distribution transformer and a custom service ground.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.635-640
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• 2016

This paper dealt with the deterioration characteristics and an on-line diagnosis equipment for SPDs (surge protective devices). An accelerated aging test was carried out using a $8/20{\mu}s$ standard lightning impulse current to analyze the changes of electrical characteristics and to propose the diagnostic parameters and the criterion for deterioration of ZnO varistor which is the core component of SPDs. Based on the experimental results, an on-line diagnosis equipment for SPD was fabricated, which can measure the total leakage current, reference and clamping voltage. The leakage current measurement circuit was designed using a low-noise amplifier and a clamp type ZCT. A linear controller, the leakage current measurement part and a HVDC were used in the measurement of reference voltage. The measurement circuit of clamping voltage consisted of a surge generator and a coupling circuit. In a calibration process, measurement error of the prototype equipment was less than 3%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.3
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• pp.100-106
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• 2013

In this paper, in order to analyze lightning impulse response characteristics in combined installations of SPDs and RCDs, surge protection coordination between SPDs and RCDs are experimentally investigated by using the combination wave generator. Six different types of single-phase residual current operated circuit-breakers with integral overcurrent protection for household and similar uses(RCBOs) being present on the domestic market are tested according to KS C IEC 61009-1 standard. As a result, when a class I SPD is located on the source side of an RCBO, all kinds of specimens are able to provide the proper coordination between the SPD and RCBOs without nuisance tripping, unintended operation or damage due to test impulse currents. However, in the case that the class II SPD is located on the load side of RCBOs, a lot of L-N mode injected currents is split into the RCBO, and a few RCBOs are damaged. Coordination between SPDs and RCDs is not valid and a role of SPDs is of no use. When combining SPDs with RCDs, it is necessary to select SPDs and RCDs in consideration of the protection voltage level of metal oxide varistor embedded in RCDs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.130-134
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• 2020

Metal oxide varistors (MOVs) protect circuits and devices from transient overvoltages in electric power systems. However, a MOV continuously deteriorates owing to manufacturing defects or repetitive protective operations from transient overvoltages. A deteriorated MOV may result in a short circuit or a line-ground accident. Previous studies focused on the analysis of deterioration mechanisms and condition diagnosis techniques for MOVs owing to their recent growth of use. An accelerated deterioration experiment under the same conditions in which a MOV operates is essential. In this study, we designed and fabricated a surge generator that can apply a surge current to a MOV connected to AC mains. The coupling network operates at a low impedance against the surge current from the surge generator and transfers the surge current to the MOV under test. It also acts as a high impedance against AC mains for the AC voltage not to be applied to the surge generator. The decoupling network operates at a high impedance against the surge current and blocks the surge current from AC mains. It also acts as a low impedance against AC mains for the AC voltage to be applied to the MOV under test. The prototype surge generator can apply the 8/20 us up to 15 kA on AC voltages in the approximate range of 110~450 V, and it fully operates on a LabVIEW-based program.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.5
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• pp.95-103
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• 2013

Protection of the electrical and electronic equipment against surges in low voltage AC power distribution systems is based on wide applications of surge protective devices(SPDs). Cascade application of SPDs located at the service entrance of a building and near sensitive equipment is intended to ensure the optimal voltage protection level and energy sharing among cascade SPDs. In this paper, when surges impinge at the service entrance of the building of interest, the protection characteristics of two-stage cascade SPD systems were investigated. The influence of the distance between the upstream and downstream SPDs on the voltage protection level and energy sharing of the two-stage cascade SPD systems were analyzed experimentally. It was found that the energy sharing of two-stage cascade SPD systems strongly depends on the distance between the two SPDs and the component of SPD. As the distance between the two SPDs increases, the energy absorbed by the upstream SPD increases while the energy absorbed by the downstream SPD decreases. Consequently, it is desirable to select the upstream and downstream SPDs having the proper energy capability with due consideration of the distance between the two SPDs.