• Proceedings of the KIEE Conference
• /
• 2001.11a
• /
• pp.213-215
• /
• 2001

We investigated the frequency characteristics of surges induced on Lan equipments by using V-F converter. which installed on the second part of protection system. We stored and analyzed the frequency converting data with the amplitude of overvoltage. In addition. The data acquisition system was made so that we could be examine the results wave through WEB. From this results, it is found that this frequency analysis could be helped for design and protection of various undesired surges.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.53 no.3
• /
• pp.149-156
• /
• 2004

This paper deals with the effective protection method for the household electric appliances against lightning surges invading from the Power lines. Direct or induced lightning is the main cause of the breakdown of household electric appliance. The most effective protection method is to install SPDs(surge protective devices) at household electric appliances. If SPDs were not installed at most household electric appliances, it is necessary to install SPDs on the mains. Therefore the propagation aspect and protection methods of lighting surges coming into household electric appliances through the mains was experimentally investigated. The in actual-sized test circuits results of protection method for 8 household electric appliances including computer monitors and TV set could be summarized as follows: The breakdown characteristics of household electric appliances from lightning surges were significantly changed with the their input impedance. Namely, the types of input impedance are classified into infinite, resistive or inductive impedances. Especially, the monitor for computer with inductive input impedance from lightning surges was relatively weak against lightning surges. It was confirmed that the self inductance of branch circuits on the mains have protection effect for household electric appliances against lightning surges invading from the power lines. Also the varistors installed at cabinet panel or circuit-breaker were more effective than multi-tap outlet with varistors. When installed varistors in cabinet panel and multi-tap outlet together, the surge protection effect is much more excellent in technical and economical aspects.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.907-910
• /
• 1992

This paper deals with the mesurement and the analysis by means of EMTP simulation for the fast-rising switching surges. The fast-rising surges having up to 180ns of front time and 3.42 p.u of peak value were measured at the 154KV substations. The fast-rising surges are expected to cause electric breakdown because the penetrating surges to the transformers result in the higher stress in the winding end than the average stress along the winding.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.4
• /
• pp.117-123
• /
• 2011

Lightning and switching surges propagating through the grounding conductors lead to transient overvoltages, and electronic circuits in information technology systems are very susceptible to damage or malfunction from the electrical surges. Surge damages or malfunctions of electrical and electronic equipment may be caused by potential rises. To solve these problems, it is very important to evaluate the ground surface potential rises and hazardous voltages such as touch and step voltages at or near the grounding systems energized by electrical surges. In this paper, the performance of grounding systems against the surge current containing high frequency components on the basis of the actual-sized tests is presented. The ground surface potential rises and hazardous voltages depending on impulse currents for vertical or horizontal grounding electrodes are measured and analyzed. Also the touch and step voltages caused by the impulse currents are investigated. As a result, the ground surface potential rises, the touch and step voltages near the grounding electrodes are raised and the conventional grounding impedances are increased as the front time of the injected impulse currents is getting faster.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.6
• /
• pp.67-74
• /
• 2010

Most of domestic low-voltage consumers are supplied from the TN-C system of KEPCO, but their load installations have established according to the national statutory standard for electrical installations based on the TT system. In this work, to propose the proper system earthing arrangements of ensuring the protection of information-technology equipment against lightning surges, the protection performance of TT and TN systems against lightning surges was investigated. As a result, when lightning surge was injected to the neutral line of distribution system, the potential difference between the equipment earth terminal and neutral point of low-voltage mains in a TT system was significantly raised. The TT system is not advised due to the risk of damage to the sensitive computer equipment. Main equipotential bonding is an important requirement for protection of low-voltage installations against lightning surges. The TN system provides the best means to reduce the incoming lightning surges through the neutral line of low-voltage service systems. In addition, It is highly recommended to install the additional earthing at the service position of low-voltage consumers.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.3C no.4
• /
• pp.117-122
• /
• 2003

The AC power lines and signal lines of info-communication networks are routed on overhead poles and are highly exposed to lightning strikes. Due to the potential difference between grounding points of AC power lines and signal lines, the electronic equipments connected to the signal lines can easily be damaged by lightning surges. In this work, in order to develop reliable methods of protecting information and communication facilities from lightning surges, the reliability and performance of SPDs (surge protective devices) were experimentally investigated in an actual-sized test circuit. The behaviors of SPDs against lightning surges from AC power lines and signal lines and the coordinated effects of SPD installation methods were evaluated. As a consequence, it was confirmed that the bypass arrester methods and common grounding system are both highly effective.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.8
• /
• pp.96-101
• /
• 2012

A surge protection device of the metal oxide varistor(MOV) has been commonly used for preventing electrical damage in many electronic equipments. The MOV has a property that leakage current is increased and might be permanently damaged when it is exposed continuously to the electrical stresses such as lightening surges. In this paper, we propose a novel surge protection circuit adopting a silicon controlled rectifier(SCR) in the traditional protection circuits using the MOV device simultaneously. When lightning surges are injected to the proposed circuit, the MOV lets the surge pulses bypassing through the ground at first up to the level that SCR begins to operate. Above the threshold level of turning on the SCR, the SCR operates bypasses large surge currents to the ground. Proposed circuit was verified with a leakage current experiment and PSpice circuit simulations under the repeated surge injection environment.

• 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.

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

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.11
• /
• pp.717-723
• /
• 1999

The transient characteristics of grounding systems play a major role in the protection of power equipments, electronic circuits and info-communication facilities against surges which arise from lightning or ground faults. Electronic devices are very weak against lightning surges injected from grounding systems and can be damaged. The malfunction and damage of electronic circuits bring about bad operation performances, a lot of economical losses, and etc. Therefore, in order to obtain the effective protection measure of electronic devices from overvoltages and lightning surges, the analysis of the transient grounding impedances in essential. One of this work is to examine the transient behaviors of grounding impedances under steplike currents for various grounding systems. And the other of this work is to evaluate the transient behaviors of a grid with rods under impulse currents and to investigate the effect of grounding lead wire. Transient grounding impedances of a grid with rods under impulse current waves have been measured as a parameter of the length of the grounding leads. Z-t, Z-i and V-i curves of transient grounding impedance under impulse current waveforms have been measured and analyzed. It was found that the grounding impedance gives the inductive, resistive and capacitive aspects under steplike current. Transient grounding impedance characteristics were very different with shapes, geometries of ground electrodes. Also, they were dependent on the waveform and magnitude of impulse current.