• Proceedings of the KIEE Conference
• /
• 1997.07e
• /
• pp.1712-1714
• /
• 1997

This paper deals with the surge counter drived by lightning and switching currents. In order to install the effective surge protective devices, it is important to find the parameters of incident surges. In this paper, for the purpose of protecting the electronic circuits and counting the occuring frequency, the current driving type surge counter is designed and fabricated. The surge counter consists of surge protective divices, current detector, metal oxide varistor(MOV), rectifier, capacitor, and electromagnetic counter. This surge counter is able to count the occuring frequency of surges and to clamp lightning surge current. To evaluate the performance of the surge counter, impulse voltage and current were applied at the surge counter by the surge generator. As a result, applied surges were exactly counted and clamped.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.2
• /
• pp.178-183
• /
• 2013

The study of lightning surge have been conducted on information and communications equipment and power system. However, the research on SMPS itself is an inactive field. This paper analyzes surge current path of flyback converter with the combination wave generator by lightning surge. Also, this paper discloses that there exists the surge current with high-frequency component besides the low-frequency component based on the standard surge current. This high-frequency surge current is the major reason to damage the semiconductor devices such as FET and IC. To confirm the validity of the proposed issue, the analysis and experimental results are presented.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2008.05a
• /
• pp.289-292
• /
• 2008

This paper describes the electrical characteristics of the ZnO surge arrester according to the variation of surrounding conditions. To investigate the characteristics of degraded ZnO surge arrester, 8/20 [${\mu$s], 2.5 [kA] impulse currents were applied to the ZnO surge arrester to be test. To present the effect of the surrounding con야tions, the leakage currents of ZnO surge arrester were measured to the surrounding temperature and wet conditions. As a result, the increase of ambient temperature causes the increase of resistive leakage current of ZnO surge arrester. Also, in the wet test, the outside leakage current through the ZnO surge arrester housing is much larger than the intrinsic leakage current.

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

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.2
• /
• pp.190-195
• /
• 2013

Vacuum circuit breaker(VCB) has been widely used for interruption of load current and fault current for high voltage motor in the industrial field. Its arc extinguishing capability is excellent compared to other breakers. But it has the potential to cause multi reignition surge by high extinguishing capability. Surge voltage is generated by the opening and closing of VCB. Multi reignition surge of VCB is steep-fronted waveform. It may have a detrimental effect on the motor winding insulation. So, most of users install a protection device to limit steep-front waveform at the motor terminal or breaker side. So, most of users install a protection device at the motor terminal or breaker side. This protective device is surge absorber(SA) such as ZnO and RC type. In this study, we analyzed whether there is any effect when two type SA is applied to the VCB multi reignition surge. We confirmed that ZnO SA is slightly more effective than RC SA for reduction of multi reignition surge.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.190-193
• /
• 2001

ZnO varistors have been widely used to protect power system and electronic system against overvoltages based on their excellent nonlinearity. In order to increase their protection capability, the fracture and protection technologies of arresters have to study according to their applications, namely ImA DC voltage, leakage currents, impulse residual voltages, withstanding capability to impulse surge, and energy absorption capability. ZnO varistors which have nonlinear current-voltage characteristic name a number of failure mechanism when ZnO elements absorb surge energies. Failure mode by thermal stress and Pin hole are among the most common failure mechanism at the high current surge current. In this study, the fracture mechaism of power arresters are introduced and protection technologies are researched. In particular the effect of thermal stress by surge currents to ZnO elements and methods against arc surge energy through withstand structure design of arrester are discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.3
• /
• pp.79-86
• /
• 2013

In order to analyze the electrical performance of ZnO surge arresters stressed by the combined DC and AC voltages that are generated in DC/AC converter systems, the leakage current properties of ZnO surge arrester blocks deteriorated by impulse currents were investigated. The test specimens were deteriorated by the 8/$20{\mu}s$ impulse current of 2.5kA and the leakage currents flowing into the deteriorated zinc oxide(ZnO) arrester blocks subjected to the combined DC and power frequency AC voltages are measured. As a result, the leakage currents flowing through deteriorated ZnO surge arrester blocks were higher than those flowing through the fine ZnO surge arrester blocks and the larger the injection number of 8/$20{\mu}s$ impulse current of 2.5kA is, the greater the leakage current is. The leakage current-voltage curves(I-V curves) of the fine and deteriorated ZnO surge arrester blocks stressed by the combined DC and AC voltages show significant difference in the low conduction region. Also the cross-over phenomenon is observed at the voltage close to the knee of conduction on plots of I-V curves.

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

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.4
• /
• pp.79-85
• /
• 2009

This paper describes the degradation properties of ZnO surge arresters impressed by lightning impulse currents. To investigate the deterioration behaviors of ZnO surge arresters due to lightning surges, the 8/20[${\mu}s$], 2.5[kA] standard lightning impulse currents were injected to the ZnO surge arrester under test. The power frequency AC and DC leakage currents flowing through the ZnO surge arresters with and without the injection of lightning impulse currents were measured. As a result, the leakage currents are increased and the asymmetry of the AC leakage current is pronounced as the number of injection of the impulse current increases. The ZnO grain of the surge arrester without the injection of lightning surges are uniform but the ZnO grain of the ZnO surge arrester with the injection of lightning impulse currents are deformed. Also, it was found that the decrease of the $Bi_2O_3$ due to the lightning impulse current leads to the lack of grain boundary layer and the current concentrated by the lack of grain boundary layer play an important role to degrade nonlinear property of ZnO surge arrester blocks.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.3
• /
• pp.570-575
• /
• 2005

Malfunction by electrical surges is a serious problem on earth leakage current breakers(ELBs) used in a low voltage AC power system. In this paper, we tested ELBs according to IEC 61009-1 and KS C 4613 to analyze surge influence on ELB's malfunction. The test by application of surge voltage is specified both standards, but the test by application of surge current is specified only in IEC 61009-1. The experimental results showed that the ELBs used in this test are robust to surge voltage application, but the malfunction occurred to surge current application. Surge current is more frequent than surge voltage in actual situation. Therefore, ELBs should be tested by the surge current, and the domestic standard, KS C 4613, should includes a test procedure by the surge current application.