Chung-Seog Choi

Distribution of Potential Rise as a Function of Shape of Grounding Electrodes

In order to analyze the potential rise of grounding systems installed in buildings, a hemispherical grounding simulation system was studied. Potential rise was measured and analyzed regarding the shape and distance of the grounding electrodes by using this system. The system was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The potential rise was measured in real time by the horizontal moving probe of the potentiometer. The test grounding electrodes were fabricated through reducing the grounding electrode installed in real buildings such as the ground rod, grounding grid and so on. The potential rise was displayed in a two-dimensional profile and was analyzed regarding the shapes of the ground electrodes. The potential rise of the grounding grid combined with a ground rod was the lowest of every grounding electrode tested. The proposed results can be applicable to evaluating ground potential rise in grounding systems, and the analytical data can be used to stabilize the electrical installations and prevent electrical disasters.

Research on Assessment of Potential Interference between Individual Grounding Electrodes Using an Electrolytic Tank Modeling Method

This paper deals with the assessment of potential interference between individual grounding electrodes using an Electrolytic Tank Modeling method, When a test current was passed through a grounding electrode, potential rise was treasured and analyzed using an electrolytic tank in real time. In order to analyze the potential interference between grounding electrodes, a reduced scale modeling method was studied. Potential interference between isolated grounding electrodes was evaluated as a function of the separation distance between grounding electrodes and the configuration of grounding electrode to be induced. It was found that the separation distance between grounding electrodes was a major factor in reducing the potential interference.

A study on the carbonization characteristics of insulating materials between RCD terminals deteriorated by NaCl solutions

To protect equipments from electric leakage current, we generally use Residual Current Device(RCD). In this paper, we studied on the carbonization characteristics of insulating materials between the source terminals of RCD deteriorated by NaCl solutions. The process of ignition was taken by high speed camera. And the carbonization materials were analyzed by Fourier Transform Infrared spectrometer(FT-IR) and Differential Thermal Analyzer(DTA). In comparison with the virgin sample, the spectra of carbonized materials did not have absorption peak near 1609.5 cm/sup -1/. In the results of thermal analysis, the exothermic peaks of carbonized materials showed differences according to the number of droplets and carbonization time.

Research on Comparison of Individual and Connecting Grounding Electrode for Potential Rise Distribution

This paper deals with a comparison of individual and connecting grounding electrode for potential rise. When a test current flowed through grounding electrode, potential rise was measured and analyzed for grounding method using a electrolytic tank in real time. In order to analyze the potential rise of grounding systems, a hemispherical water tank experimental apparatus was studied. Potential rise was measured and analyzed regarding the grounding method and distance by using this apparatus. The apparatus was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The potential rise was measured by the horizontal moving probe of the potentiometer. The grounding electrodes were designed and fabricated with ground rods on a scale of one-eightieth. Potential rises of individual grounding electrode were higher than those of connecting grounding electrode. The distributions of surface potential are dependent on the distance from grounding electrode.

The Protective Countermeasure of Water Purifier PCB according to Abnormal Voltage

The electrical accident results from an insulation blackdown by over-voltage, an overheating by the excess of allowable current, a deterioration performance by the passage of time, and so on. This paper discusses how to improve the power control system of PCB in water purifier. The protecting device of present power supply control system in water purifier is composed of the varistor device which acts only for impulse-type surges. So the present system can not be protected others except the surge of impulse-type. The newly-suggested power control system in this paper is designed to protect the system by disconnecting power supply through SSR(Solid State Relay) if the value of input voltage is exceeded the setting value.

The properties of oxidation growth and overheating by poor contact

In this paper, we experimented the glowing and heating phenomenon at the contacts of copper wires, and studied the breeding process, the growing characteristics of copper oxide according to the diameter of copper wires and AC current. The surface structure, crystalline structure, compositions and calory variation of Cu2O that grew at the contacts of two copper wires were analyzed by using scanning electron microscope (SEM), metallurgical microscope, energy dispersive X-ray spectroscopy (EDX) and differential scanning calorimetry (DSC). As these results, we could know that carbonization and oxidation reaction generated on the outside of the oxide, and only oxidation reaction generated in the inside of the oxide

A Research on the Actual Conditions of the Electric Shock Hazard of a Guard Lamp

In this paper, guard lamps at three areas have been investigated to understand the actual conditions of the electric shock hazard of the guard lamps. Upon the basis of the obtained data, the actual conditions of the guard lamps were precisely analyzed in terms of the electric shock hazard. As a result of the investigation, it was turned out that many guard lamps were not installed in organized ways due to the lack of legal regulations, resulting in the increase of electric shock hazard. Therefore, it is necessary, from a point of electric shock protection view, to establish the regulations of equipment installation and management, which can be specifically applied to guard lamps.

Notice of Violation of IEEE Publication Principles New distribution class arrester ground lead disconnector design

This paper examines performance characteristics of existing distribution class arrester ground lead disconnecting devices. The paper also introduces a new Distribution Class ground lead disconnector design that not only extends the claimable detonation range well below the 20 amps specified in industry standards, but is very durable when exposed to severe arrester durability tests. Finally, this paper shows how this next generation disconnector interacts with the connected arrester to improve the overvoltage withstand capability of the arrester assembly.

Notice of Violation of IEEE Publication Principles Charge transport and electroluminescence in insulating polymers

Polymers submitted to thermo/electrical stress suffer from ageing that can drastically affect their functional behaviour. Understanding the physico/chemical processes at play during ageing and defining transport regimes in which these mechanisms start to be critical is therefore a prime goal to prevent degradation and to develop new formulation or new materials with improved properties. It is thought that a way to define these critical regimes is to investigate under which conditions (in terms of stress parameters) light is generated in the material by electroluminescence (EL). This can happen through impact excitation/ionization involving hot carriers or upon bipolar charge recombination (a definition that excludes light from partial discharges, which would sign an advanced stage in the degradation process). After a brief review of the EL phenomenology under DC, we introduce a numerical model of charge transport postulating a recombinationcontrolled electroluminescence. The model output is critically evaluated with special emphasize on the comparison between simulated and experimental light emission. Finally, we comment some open questions and perspectives.

Notice of Violation of IEEE Publication Principles On-line condition monitoring and diagnostics of power distribution equipment

Continuous on-line temperature monitoring provides the means to evaluate current condition of equipment and detect abnormality. It allows corrective measures to be taken to prevent upcoming failure. Continuous temperature monitoring and event recording provides information on the energized equipmentpsilas respond to normal and emergency conditions. On-line temperature monitoring helps to coordinate equipment specifications and ratings, determine the real limits of the monitored equipment and optimize facility operations. Using wireless technique eliminates any need for special cables and wires with lower installation costs if compared to other types of online condition monitoring equipment. In addition, wireless temperature monitoring works well under difficult conditions in strategically important locations. Wireless technology for on-line condition monitoring of energized equipment is applicable both as standalone system and with an interface with power quality monitoring system. The paper presents the results of wireless temperature monitoring of switchgear at a power plant over a two-year period.