Search

Department of Fire Safety Engineering, Jeonju University(Received April 12, 2013 / Accepted July 22, 2013)Abstract : The purpose of this paper is to evaluate the performance of a Plug-In MCCB developed for rapid power supply restoration when the MCCB is installed in a power system and to verify its reliability. Since the developed 3 Φ 3 W Plug-In MCCB can be installed on and removed from a bus bar by one touch using a plug housed at the rear, it can be replaced in a short period of time. Therefore, it can quickly respond to the normalization of a power system. When the Plug-In MCCBB is installed on a bus bar, the resistance between each phase and plug was measured to be 0.46 mΩ in average. When the Plug-In MCCB is installed, the tension in the vertical direction was measured to be 112.78 N in average, which is greater than the tension of 50 N specified in the related regulation. The withstanding voltage tests performed 5 times repeatedly by applying 6 kV to the developed Plug-In MCCB for 60 seconds shows good withstanding voltage characteristics. In addition, both the general waterproof test using a water injection method and the insulation resistance analysis using a Mega meter showed good waterproof and insulation characteristics.Key Words : tension, contact resistance, Plug-In MCCB, withstanding voltage, waterproof test

This paper analyzes the combustion diffusion pattern when a water purifier is artificially ignited outside and inside in order to provide data to examine the cause of fire of a water purifier damaged by fire. The analysis result of the combustion diffusion pattern of a water purifier shows that the combustion diffused at a higher speed when it was ignited inside the purifier than when ignited outside. It took approximately 360 seconds for the water purifier to be half-burned when ignited on the outside, and approximately 180 seconds when ignited from inside. That is, it is thought that the internal combustion speed is higher because the internal ignition causes the generated heat to be accumulated and radiated instantly. It was observed that the water purifier damaged by fire caused by external ignition showed a uniform carbonization pattern and the carbide burned down at the bottom were gradually deposited. The water purifier damaged by internal ignition showed a relatively clear boundary of carbonized surface, which formed a V-pattern. The difference in the combustion patterns presents an objective base from which to determine where the fire started. By the time the purifier was half-burned by fire, the built-in fuse had not melted and the power supply protection device did not operate. In addition, as was found in the case of the fuse damaged by a general fire, carbonization occurred at the metal holder, and it is thought that this fact may be used as a basis from which to determine the cause of a fire.

Focusing on good dispersion of carbon nanotube (CNT) in the polymeric matrix, morphological and rheological properties as well as electrical conductivity of poly(vinyl acetate) (PVAc)/multi-walled carbon nanotube (MWNT) nanocomposites were investigated. Electrical properties of the PVAc/MWNT nanocomposites were examined using a resistometer. Small amount of MWNT was observed to remarkably decrease resistivity of the nanocomposites. Internal structure of the nanocomposite materials was characterized by transmission electron microscope. Raman spectroscopy was adopted to investigate molecular motion of CNT in the composites. Moreover, rheological properties of the nanocomposites were measured using a rotational rheometer, observing increased storage ( G ′) and loss moduli ( G ʺ) as a function of frequency in an oscillatory shear mode.

The electrical fire frequently happens through careless use such as poor contact, mechanical stress on power cord sets. In this paper, we simulated a wall-model in order to investigate the patterns of fire dispersion on power cord sets which consists of vinyl cord and rubber cord, etc. The fire progress and dispersive patterns were measured by a high speed imaging system(HG-100K, REDLAKE, USA). From the results, the fire pattern of power cord sets was progressed in order of flashover, scattering and disconnection. The short-circuit of the vinyl cords happened easier than the rubber cords by the external flame. In case vinyl cord is disconnected. the fire progress is not observed because the ignition energy decreases. Whereas, the fire progressed continuously in case of the rubber cord.

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.

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

There are many electrical connection parts in the electrical apparatus. Electrical connectors (for example; an outlet or a plug, etc) are devices that connect electric energy and complete electrical circuits. In these connections, the heat is generated by the poor contact according to the slack and the vibration between an outlet receptacle and a plug pins. Excessive heat generation can occur when current, acceptable for the rating of the wire, passes through a poor contact. When overheating due to poor contact occurs, current passes through the increased resistance of a poor connection that is connected in series with the desired load. The heat is generated and the temperature increases, causing degradation of the surrounding combustibles at a focused point or small area. In this paper, it is studied the heating and electrical properties according to the poor contact at PVC insulated plug, and analyzed surface state, surface structure of the grown oxide at the contact part of PVC insulated plug pins. We expect to contribute to prevention of the electrical accident occurring at PVC insulated plug contact part on the basis of this paper.

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.