• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.409-411
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• 2004

The need for Fault Current Limiters (FCL) is associated with the continuous growth and interconnection of modem power systems and increase in dispersed generation facilities, which result in progressive increase in the short circuit capacity far beyond their original design capacity. Fault Current Limiters (FCL) clips the fault currents and reduces the electromechanical stresses on the network and the need to handle excessive fault currents. In addition, the reduction of the fault duration Provided by the limiter should increase the power transmission capability and improve the dynamic stability. This paper proposes the model of resistive type superconducting fault current limiter using EMTDC(Electromagnetic transients for DC analysis program). In order to verify the effectiveness of the SFCL, in this paper, the analysis of fault current in a transmission system through the EMTDC based simulation by using the modeled component of a resistive type SFCL is peformed and the detailed results are given.

• 조명전기설비학회논문지
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• 제28권12호
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• pp.30-37
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• 2014

Recently, Concerns of imbalance for power supply has been raised by the increase of electric power consumption, but the interest of electric safety is still lacking due to the incompleteness of regulations. Particularly, Arcing fault, direct cause of electric fire accidents, is difficult to detect, interrupt due to unformal signal behaviour in previous research and apply to real system. In this paper, Arcing fault simulator device was fabricated to investigate the characteristics of series arcing fault and simulated the faults in various real load. Also, this study are analysed arcing fault signal by using the harmonic analysis of the acquired data from the current of the power supply and proposed the methods to prevent the series arcing fault accidents in advance.

• 대한기계학회논문집
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• 제18권1호
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• pp.127-138
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• 1994

The application of fault tree technique to the analysis of compressor failure is considered. The techniques involve the decomposition of the system into a form of fault tree where certain basic events lead to a specified top event which signifies the total failure of the system. In this paper, fault trees are made by using fault train of screw type air compressor failure. The fault trees are used to obtain minimal cut sets from the modes of system failure and, hence the system failure rate for the top event can be calculated. The method of constructing fault trees and the subsequent estimation of reliability of the system is illustrated through compressor failure. It is proved that FTA is efficient to investigate the compressor failure modes and diagnose system.

• Journal of information and communication convergence engineering
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• 제19권3호
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• pp.175-179
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• 2021

Enhancing the reliability of the system is important for recent system-on-chip (SoC) designs. This importance has led to studies on fault diagnosis and tolerance. Fault-injection (FI) techniques are widely used to measure the fault-tolerance capabilities of resilient systems. FI techniques suffer from limitations in relation to environmental conditions and system features. Moreover, a hardware-based FI can cause permanent damage to the target system, because the actual circuit cannot be restored. Accordingly, we propose a simulation-based FI framework based on the Verilog Procedural Interface for measuring the failure rates of SoCs caused by soft errors. We execute five benchmark programs using an ARM Cortex M0 processor and inject soft errors using the proposed framework. The experiment has a 95% confidence level with a ±2.53% error, and confirms the reliability and feasibility of using proposed framework for fault analysis in SoCs.

• 한국안전학회지
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• 제30권3호
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• pp.100-106
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• 2015

A module or independent subtree is a part of a fault tree whose child gates or basic events are not repeated in the remaining part of the fault tree. Modules are necessarily employed in order to reduce the computational costs of fault tree quantification. This quantification generates fault tree solutions such as minimal cut sets, minimal path sets, or binary decision diagrams (BDDs), and then, calculates top event probability and importance measures. This paper presents a new linear time algorithm to detect modules of large fault trees. It is shown through benchmark tests that the new method proposed in this study can very quickly detect the modules of a huge fault tree. It is recommended that this method be implemented into fault tree solvers for efficient probabilistic safety assessment (PSA) of nuclear power plants.

• International Journal of Safety
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• 제11권2호
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• pp.22-25
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• 2012

This paper deals with the problem of fault diagnosis for identifying a single fault when the number of assumed faults is larger than that of predictive variables. Principal component analysis (PCA) is employed to isolate and identify a single fault. PCA is a method to extract important information as reducing the number of large dimension in a process. The patterns of all assumed faults can be recognized by PCA and these can be employed whether a new fault is one of predefined faults or not. Through PCA, empirical models for analyzing patterns can be trained. When a single fault occurs, the pattern generated by PCA can be obtained and this is used to identify a fault. The performance of the proposed approach is illustrated in the actuator benchmark problem.

• 대한전기학회논문지:전력기술부문A
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• 제52권1호
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• pp.29-35
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• 2003

This paper presents a fault location algorithm when there are parallel circuits in power system networks. In transmission networks, a fault location method using the distribution factor of fault currents is introduced and in distribution networks a method using direct 3-phase circuit analysis is developed, because the distribution networks are unbalanced. The effect of parallel circuits in fault location is studied in this paper. The effect is important for the range of protecting zones of distance relay in transmission networks and fault location in distribution networks. The result of developed fault location algorithm shows high accuracy in the simulation that using the EMTP.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1049-1055
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• 2013

DC motors are widely used in industries like cement, paper manufacturing, etc., even today. Early fault identification in dc motors significantly improves its life time and reduces power consumption. Many conventional and soft computing techniques for fault identification in DC motors including a recent work using model based analysis with the help of fuzzy logic are available in literature. In this paper fuzzy logic and norm based wavelet analysis of startup transient current are proposed to identify and quantify the armature winding fault and bearing fault in DC motors, respectively. Results obtained by simulation using Matlab and Simulink are presented in this paper to validate the proposed work.

• International Journal of Safety
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• 제7권1호
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• pp.15-20
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• 2008

The primary goal of this study is to analyze fire hazards of electric home appliances such as electric iron and electric heater using fault tree analysis(FTA). A fault tree(FT) is constructed and used to analyze fire hazards in electric home appliances. The fault tree is built from events that may occur in electric home appliances. The failure rate of basic events are derived from the value of experimental results and reference. And an algorithm analyzing fire in electric home appliances is suggested. We show how fault tree analysis, carried out by means of failure rate, is able to diagnose fire hazards of electric home appliances in a precise manner. We present numerical results such as fire probability of electric home appliances, importance measure, fire cause, etc. It can be helpful in preventing the fire hazards in electric home appliances.

• 한국소음진동공학회논문집
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• 제14권8호
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• pp.675-683
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• 2004

The motor current signature provides an important source of the information for the faults diagnosis of three-phase induction motor. The theoretical principles behind the generation of unique signal characteristics, which are indicative of failure mechanisms, are Presented. The fault detection techniques that can be used to diagnose mechanical Problems, stator and rotor winding failure mechanisms, and air-gap eccentricity are described. A theoretical analysis is presented which predicts the presence of unique signature patterns in the current that are only characteristics of the fault. The predictions are verified by experimental results from a special fault Producing test rig and on-site tests in a steel company. And this study have made new diagnostic algorithm for the operating induction motors with the test results. These developments are including the use of monitoring and analysis of electric current to diagnose mechanical and electrical problems and gave the precise test results automatically.