Papers by Keyword: Arcing

Abstract: Electrical wires with melted ends showing beaded, drop-shaped, and pointed shapes are frequently encountered after fires that may provide useful information on the cause and development of the fire.Various methods have been studied for differentiating between primary arcing beads, (indicating arcing as the fire cause) and secondary arcing beads (indicating arcing as a result of the fire). There are few studies carried out on the melting globules produced due to fire heat. Also, in some major cases, primary arcing beads and secondary arcing beads are difficult to be identified by using one method. In this study, a full scheme of differentiating methods between simulated samples of melting globules, primary arcing beads and secondary arcing beads are processed with macroscopic investigation. The in-depth composition of carbon quantitative analysis and metallurgical analysis of these samples have been studied. The results of this study has proved that the real cases are compatible with simulated ones.

Abstract: In general, the presence of moisture and other impurities inside the insulator or oil can cause the breakdown of the power transformer. Polarization and Depolarization Current (PDC) is one of the technique to assess the condition of insulation oil in power transformer and can be applied in many electrical apparatus such as power cables and on load tap changer as well as to estimate conductive and moisture content of the insulation. Basically, it is a technique that is based on time domain measurement and has been used since 1990. For this research, the PDC data will be analyzed using graphical method and statistical technique to classify the transformer faults into a proper range. Lastly, it will be validated with the results from previous research. The output of the research work revealed that in term of the sequence, the results obtain in both graphical technique and the statistical technique is identical with the results presented in previous research. Hence, the range of the faults started with partial discharge, followed by arcing and lastly is the overheating.

Abstract: The influence of damages on the insulator’s surface in the distribution system is investigated in this paper. The circular resin is used as the specimen under high voltage direct current (HVDC) between the electrodes with diameter of 2 mm and distance between both electrodes are 35 mm. There are three cases in the experiment and it was tested in environmental condition under dry surface, single droplet and double droplets. The HVDC had been applied to the electrodes, the level of applied were 5, 10, 15, 20, 25, 30 and 35 kV. The results show that the arc occurs rapidly in the case of single and double drops with compared to dry surface. The movements of the water drop of the single and doubles are pretty similar, but the arc occurs quickly in the double drop in comparison with single drop owing to double drops stretch to each other. The double drops take a lower voltage on stretching, whereas the single drop takes higher because the double drops have much more densities than single drop. Besides, the double drops act as a bridge allow the electrical field generated from both electrodes pulled them resulting in arcing easily. In conclusion, the droplets on the surfaces cause the leakage current and it has an effect on the stability of the distribution system.

Abstract: The partial discharge on the insulator surfaces usually occurred in the distribution system. The influence of water droplets is investigated in this paper. This experiment used a circular resin specimen under High Voltage Alternating Current (HVAC) field stress that was applied to the electrodes with a diameter of 2 mm and with a distance between both electrodes of 35 mm. For this methodology, both a single droplet and also double droplets were used on surfaces and the voltage level was adjusted by 15 kV. Results showed that, firstly, the corona phenomenon occurred around the circular electrode after the water droplets on the specimen surface were stretched to each other, but the double drops took a lower voltage level for the stretching than the single drop. In addition, the double drops acted as a bridge, allowing an electrical field to be generated from both electrodes. This pulled them, easily resulting in arcing. In conclusion, water droplets are a main factor to the aging that occurred on the insulators surfaces and this effect is presented in this experiment.

Abstract: The lecture will give an overview of the manufacturing technique of ceramic target materials based on ZnO and TiO2. Sintering and plasma spraying techniques are typically used. Also special bonding procedures have to be established in order to join ceramic target materials to metallic carriers. Metallic and ceramic target materials will be compared with respect to target materials processing and sputtering experiences as well. In addition planar and cylindrical targets will be briefly discussed as sputtering of large substrates is strongly moving towards cylindrical cathode applications.