• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.08a
• /
• pp.142-145
• /
• 2002

This paper describes an influence of system voltage harmonics on arrester deterioration diagnostic techniques based on leakage current measurement because the resistive current is composed of two components caused by nonlinear characteristics of arrester and by system voltage harmonics. Resistive leakage currents of arresters, which can be evaluated by the third harmonic component of total leakage currents, increase with its deterioration progress. In this paper, we developed a PSpice model for ZnO arrester to simulate the harmonics' effect described above. In simulation, pure sinusoidal voltage and the $3^{rd}$ harmonic voltage are applied to the model, and the leakage current changes are compared. The simulation results showed that the magnitudes of resistive leakage current depend not only on the phase of system voltage harmonics but also on the magnitude of it.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.8
• /
• pp.1397-1404
• /
• 2007

It is important to measure the resistive component separately from the total leakage current at power distribution line. It is because electric disasters such as electric shock and fire are caused mainly by the resistive component of the total leakage current. In this paper, a new theory for measuring the resistive component separately from the total leakage current is suggested, and is embodied to an actual circuit using operational amplifiers, analog switch and R-C low pass filter. Through experiments for various cases containing both the resistive and capacitive leakage currents, the suggested algorithm is confirmed to be able to measure the resistive leakage current within 4.1% of error even when the capacitive leakage current is much bigger than the resistive one. The suggested method is expected to lower the total cost because it can be realized using simple and cheap devices, and implies the measuring time can be possibly reduced because the resistive leakage current is computed exactly from the signals during only a half period of power voltage.

• Journal of the Korean Society of Safety
• /
• v.33 no.3
• /
• pp.27-32
• /
• 2018

Nowadays, to prevent electrical accidents in Korea, inspectors directly performed checking general electrical facilities as a cycle from every one to three years. It is difficult to presuppose an omen because intact conditions of electrical equipments are not kept at the time of inspection. In this paper, in order to ensure effectiveness of an online basis electric inspection, we developed an electrical safety IoT system using LoRa communication technology to enable monitoring mainly electrical safety components such as overcurrent, overvoltage, resistive leakage current, and power. Then we proposed a method for verifying performances of the prosed electrical safety IoT system. Resistive leakage currents are calculated by using difference of phase between voltages and currents. We verified that average errors are 0.97%, which reference goal is ${\pm}5%$ for a device, through reliability test according to conditions. Results of this research can be used as basic study materials to develop technologies for measuring three phase leakage current and for implementing public electrical safety. platform.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.05b
• /
• pp.73-75
• /
• 2004

Resistive leakage current following arresters is an important indicator of ageing, but total leakage current and its harmonic analysis are widely used in diagnosing arrester soundness because of difficulties in measuring resistive leakage current. In this paper, we proposed a new method for measuring resistive leakage current, which is quite different from the conventional methods such as a self-cancel method and a synchronous rectification method. The proposed method is based on that the magnitudes of resistive leakage currents are equal at the same voltage level. To confirm the possibility of the proposed method. we fabricated a leakage current measurement device and designed an analysis program that can analyze resistive leakage current. Comparing with other methods. this technique does not need a complex circuitry and is very simple to complete.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2006.05a
• /
• pp.338-341
• /
• 2006

This paper presents the leakage current characteristics of ZnO varistors exposed to the $8/20{\mu}s$ lightning impulse currents as functions of the number of injection and amplitude of impulse currents. The surge simulator system ECAT that can generate $8/20{\mu}s$ impulse currents with a peak short-circuit of $5[kA_p]$ was used. Leakage currents flowing through ZnO varistors subjected to the $8/20{\mu}s$ impulse currents were measured under 60 Hz AC voltages. The trend curves of resistive leakage current of ZnO varistors were analytically calculated.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.5
• /
• pp.257-262
• /
• 2006

To evaluate the change in protective levels of zinc oxide (ZnO) varistors after the surge absorption, this paper investigated the effects of the number of injection and amplitude of lightning surges on the life of ZnO varistors for low voltages. Leakage currents flowing through ZnO varistors subjected to the $8/20{\mu}s$ impulse currents under 60 Hz AC voltages were measured. The surge simulator system ECAT that can generate $8/20{\mu}s$ impulse currents with a peak short-circuit of 5 $[kA_p]$ was used. The ZnO varistor leakage current increases with exposure to impulse current, and the number of injection of $8/20{\mu}s$ impulse currents to breakdown was inversely proportional to the amplitude of the test current. Behaviors of ZnO varistor leakage currents were strongly dependent on the number of injection and amplitude of $8/20{\mu}s$ impulse currents. ZnO varistors degrade gradually when subjected to impulse current, and the resistive leakage current flowing through ZnO varistors subjected to the $8/20{\mu}s$ impulse currents under 60 Hz AC voltages was significantly increased after a certain number of injection that is dependent on the amplitude of the test impulse current. As a result, the life of ZnO varistors mainly depends on the amplitude and occurrence frequency of lightning surges.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.5C no.3
• /
• pp.131-137
• /
• 2005

This paper describes a new approach to the algorithm and fundamental characteristics of the device for monitoring the leakage currents flowing through zinc oxide (ZnO) surge arresters. In order to obtain a technique for a new on-line monitoring device that can be used in the deterioration diagnosis of ZnO surge arresters, the new algorithm and on-line leakage current detection device for extracting the resistive and capacitive currents using the phase shift addition method were proposed. The computer-based on-line monitoring device can sense accurately the power frequency leakage currents flowing through ZnO surge arresters. The on-line leakage current monitoring device of ZnO surge arresters proposed in this work has the high sensitivity compared to the third harmonic leakage current detection devices. As a consequence, it was found that the proposed leakage current monitoring device would be useful for forecasting the defects and degradation of ZnO surge arresters.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.6
• /
• pp.605-610
• /
• 2016

The ELCB(: Earth Leakage Circuit Breaker) is the only way being used to prevent accidents from happening caused by electrical disaster. However, the existing ELCB has a limit to prevent damages to life and property due to a electric fire and a human body electric shock caused by the resistive leakage current, because of detecting the total leakage current in the block range of 15mA~30mA. It also has problems such as reduced productivity and reliability due to malfunctions by capacitive leakage currents. In this study, we have implemented the algorithm for the resistive leakage current detection technique and developed the resistive leakage current detection module based on a MSP430 processor, 16bit signal processor and this module can be operated in a desired block threshold within 0.03 seconds as specified in KS C 4613.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1572-1573
• /
• 2006

This paper presents electrical properties of Zinc Oxide(ZnO) surge arrester blocks under the power frequency AC voltages and various temperatures. The leakage current, $I_{R}-V$ curios and power dissipation for the fine and aged ZnO surge arrester blocks were measured as a function of the temperatures and applied voltages. When the temperature is increased from $50\;[^{\circ}C]$ to $150\;[^{\circ}C]$, the total leakage current significantly increased at the sane applied voltage level. Also, the resistive leakage currents and power dissipation were increased with increasing temperature. The leakage current and power dissipation of the aged ZnO arrester blocks were higher than the fine ZnO arrester blocks.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1305-1306
• /
• 2008

In this work, in order to investigate the effect of lightning impulse currents on ZnO surge arrester. and the deterioration characteristics of ZnO surge arrester, 8/20 [${\mu}s$], 2.5 [kA] impulse currents were applied to the ZnO surge arrester under test. The leakage currents of ZnO surge arrester were measured and ZnO element was analyzed by X-ray photoelectron spectroscopy. As a result, the resistive leakage current of ZnO surge arrester was increased with the injection number of lightning impulse currents.