• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2392-2401
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• 2018

Creepage discharge faults in air on solid insulating material play a vital role in degradation and ageing of material which ultimately leads to breakdown of power equipment. And electric discharge decompose air in to its by-products such as Ozone and $NO_x$ gases. By analyzing air decomposition gases is a potential method for fault diagnostic in air. In this paper, experimental research has been conducted to study the effect of creepage discharge on rate of generation of air decomposition by-products using different insulating materials such as RTV, epoxy and fiberglass laminated sheet. Moreover XRF analysis has been done to analyze creepage discharge effect on these insulating materials. All experiments have been done in an open air test cell under constant temperature and pressure conditions. While analysis has been made for low and high humidity conditions. The results show that the overall concentration of air decomposition by-products under creepage discharge in low humidity is 4% higher than concentration measured in high humidity. Based on this study a mathematical relationship is also proposed for the rate of generation of air decomposition by-products under creepage discharge fault. This study leads to indirect way for diagnostic of creepage discharge propagation in air.

• 전기의세계
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• v.17 no.3
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• pp.7-28
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• 1968

When a insulator plate is inserted to the discharge path of a space discharge gap in which the field strength is not uniform, the spark voltage under the atmospheric pressure between the electrodes decreases or rises according to the position of the insulating plate. Also it is reported that if a metallic barrier plate is inserted to the discharge path of the same space discharge gap, similar variations of spark voltage are found. Speaking briefly, mensioned above are the spark voltage characteristics when an insulator or metallic barrier is inserted to the space discharge gap. Also some experimental results, concerning to the surface creepage flash over characteristics at the case when an insulator barrier is inserted to the discharge path of a surface creepage discharge gap, were reported by Peek. But up to now there are no reports on surface flash over voltage characteristics at the case when a metallic barrier is inserted to the surface creepage gap. In this study the effects of a conducting metallic barrier inserted to the path of a surface creepage discharge gap on the flash over voltage characteristics are investigated theoretically and experimentally, and got some important results, clearing the effects of the position and width of a conducting barrier is inserted, the surface flash over voltage characteristics appear as an Inverse N or W Characteristics. Such theoretical or experimental results may have some relation not only with the effects of dry belt and snow on suspension insulators, but also with the effects of dirty zone or water drops on the surface creepage flash over voltage.

• Journal of the Korean Society for Railway
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• v.17 no.1
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• pp.19-27
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• 2014

Urban railway vehicles operate in downtown areas. Due to increases in the number of passengers and changes in the service plans, railway vehicles are expected to operate on sharp curved tracks. However, on these tracks, the running stability of the railway vehicles is significantly decreased and the creepage is increased. Creepage causes the wheel/rail to wear and vibration. Therefore, reducing the creepage helps ensure the running stability and can be beneficial for the environment and cost. In this paper, the longitudinal creepage is analyzed using a railway vehicle model on a sharp curved track. Furthermore, in order to minimize the problems when a railway vehicle runs on a sharp curved track, the characteristics of a bogie are optimized using response optimization.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.2
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• pp.169-173
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• 2010

Because of power consumption increase, global warming, and limitation of installation, not only high reliability and interruption capability but also compact and light power apparatuses are needed. In this paper, E field calculation and experiment were processed to identify the influence of the shape of end shield and gap distance. It is expected that the results of FEM simulation and experiments could be the basic data to develop VI. the results of FEM simulation and experiments are as following. Firstly, maximum E fields were compared by means of finite element method as a function of the shape of end shield. 3 types of models were used to analyze maximum E field of each model and the influence of shape of shield could be identified. As a result, proposed L type shield could reduce the maximum E field by 20%. Secondly, the influence of the gap distance between end shields on E field was analyzed. As the gap distance become short the gap distance between inner walls of ceramic also become short. And the maximum E field concentrated on inner wall of ceramic finally increased. Thirdly, the experiment was conducted by fabricating each prototype. As a result, no creepage occurred in shieldless model. In other words, creepage occurred in the shield-installed models. And creepage inception voltages were different from each other because of the difference of maximum E field. Fourthly, The equation that shows relation between calculated E field and measured creepage inception voltage was proposed as a result of FEM analysis and experiment. It is concluded that when designing VI this equation could be important data to reduce time and cost by identifying indirectly the optimal gap distance and the shape of shield required to prevent creepage.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.231-239
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• 2009

Traction and braking of trains are due to the rolling contact of the wheel on the rail, and the rolling contact is fundamental to an understanding of the behavior of the railroad system. The way in which the forces are transmitted in the rolling contact is complex and highly nonlinear. This paper describes a rolling contact theory, a creepage model between wheel and rail, and a dynamic model of the tilting train Hanvit-200. The validity of the model is verified through simulation study using Simulink.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.465-470
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• 2009

This paper discusses the numerical study on the dynamics of the high-speed EMU by developing the 34 degrees-of-freedom (DOF) lumped parameter model including the effect of the creepage. In order to reflect the creepage, the Kalker's wheel-rail contact theory is introduced in the proposed model. The dynamic analysis using $Matlab^{(R)}$ software is conducted, and its results are compared with those from ADAMS/Rail to investigate the validity of the proposed 34-DOF lumped parameter model. It is demonstrated that the results from the numerical study are similar to those from ADAMS/Rail. In addition, the critical design parameters of high-speed EMU are examined, and the design guidelines for reducing vibration and enhancing ride quality are proposed.

• Current Optics and Photonics
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• v.2 no.4
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• pp.348-355
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• 2018

How to measure the creepage distance of an insulator quickly and accurately is a problem for the power industry at present, and the noticeable concern is that the high voltage insulation equipment cannot be measured online in the charged state. In view of this situation, we develop an on-line measurement system of creepage distance for high voltage insulators based on binocular stereo vision. We have proposed a method of generating linear structured light using a conical off-axis mirror. The feasibility and effect of two ways to solve the interference problem of strong sunlight have been discussed, one way is to use bandpass filters to enhance the contrast ratio of linear structured light in the images, and the other way is to process the images with adaptive threshold segmentation and feature point extraction. After the system is calibrated, we tested the measurement error of the on-line measurement system with a composite insulator sample. Experimental results show that the maximum relative error is 1.45% and the average relative error is 0.69%, which satisfies the task requirement of not more than 5% of the maximum relative error.

• Progress in Superconductivity and Cryogenics
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• v.14 no.4
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• pp.20-23
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• 2012

Superconducting equipment has been actively investigated for securing the environment and energy technology (ET) in various parts of the world. Despite these movements, a high voltage cryogenic bushing, which plays an important role of interconnection between the electric power systems and superconducting devices, has not been fully developed due to severe insulation requirements. A gas insulated cryogenic bushing has been investigated as one of our projects since 2010. As a basic step to obtain the design parameters for cryogenic bushing, we focused on the surface flashover characteristics of glass fiber reinforced plastic (FRP) in several insulation gases. For the surface flashover tests, several insulation gases including $SF_6$, $CF_4$ and $N_2$ gas were prepared. Various length of FRP specimens were fabricated in order to obtain the fundamental data for creepage distance of FRP. The first specimen group was from 2 mm to 10 mm with 2 mm intervals and the second specimen group was from 20 mm to 100 mm with 20 mm intervals. And the gas pressure was varied from 1 bar to 4 bar. An AC overvoltage test and a lightning impulse test were performed. Then the experimental results of surface flashover were obtained and analyzed. Based on these results, it would be possible to design the optimum creepage distance of FRP in a cryogenic bushing.

• 전기의세계
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• v.19 no.2
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• pp.12-17
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• 1970

In the design of electrical equipment insulation, it is customary to place pressboard and other insulating material at right angle to the electrical discharge path, which is based on the insulation tests performed on equipment under various conditions such as types of insulation, applied voltage and other unique situations. Since electrical equipment manufacturing started only recently, there is a scarcity of available data on insulation problems, which make it difficult for the design engineers. The author untook this study to provide such analytical design data for various conditions based on the experiment conducted on the equipment being manufactured, thus reducing possible errors in the process.

• Journal of the Korean Society for Railway
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• v.11 no.2
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• pp.176-181
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• 2008

This paper presents results from experimental analysis of a friction-driven wheel responsible for generating wheel squeal noise. Squeal noise generating mechanism has been examined under the laboratory condition by the model rig on a small scale. Creep characteristics and squeal noise were observed by changing the possible variables, such as relative velocities and friction coefficients in time- and frequency-domain.