Evaluation Of Protection Devices Research Articles

State assessment of protective devices based on data of information processing system

At present, the evaluation of relay status maintenance depends on a large amount of manpower. However, the data sources of relay protection devices and fault recorder information system (as known as the information processing system) have reached the basic requirements of online prediction of status evaluation of protection devices. Taking the exported information as the data source, according to the configuration file information, the state-space information that can be monitored by the protection device can be automatically extracted, and then the automatic extraction of the historical state of the protection device and the calculation of the coefficient of the state-transfer matrix are completed. Using Markov state space model method, the probability of each state that can be monitored by protection device was calculated, and the state of protection is evaluated. Finally, the operation data of CSC-101B protection device are selected as an example. The correctness and effectiveness of the method for evaluating the state of the protective device are verified.

介護者のはさまれ災害に対する入浴介助機器の保護方策の開発—入浴用ストレッチャ式電動リフトへの適用と評価—

介護者のはさまれ災害に対する入浴介助機器の保護方策の開発—入浴用ストレッチャ式電動リフトへの適用と評価—

Numerical Reconstruction of Real-Life Concussive Football Impacts

To present a protocol of numerical reconstructions of concussive events in football using MADYMO. To refine the knowledge of the dynamics associated with these events. Twenty-seven cases of concussive head impacts involving unhelmeted Australian football and rugby players were simulated using MADYMO. The cases had been previously analyzed using a video analysis protocol and were fully reconstructed for the purpose of this study. The reliability of these reconstructions had been previously assessed using a sensitivity analysis of the influence of several independent variables on the dynamical outputs. The use of a complete human model enabled consideration for morphometry, initial movements of the players, and an accurate estimate of the effective masses involved in the impacts. Mean peak values for concussion were found to be 103 g for the head center of gravity linear acceleration, 8022 rad s(-2) for the head angular acceleration, and 359 for the head impact criterion. An estimate of the average effective energy transferred to the head was 47 J. With the severity grading used in this study, the head impact power was found to be the best predictor of concussion severity. These biomechanical results compare well with other studies. They should contribute to the identification of the energy levels at which concussive impacts occur in football for the purpose of a better evaluation of protective devices in these sports.

Quantitative assessment of protection system reliability incorporating human errors

The protection system plays a vital role in maintaining a high degree of service reliability in present-day power systems. Considerable work has been done to examine different aspects of protection systems and their associated reliability. All of the reliability predictive methods are based solely on equipment failures, neglecting the human component of the protection system. In this paper, a modified Markov model is presented that incorporates human errors in reliability evaluation of protective devices. Two main types of relay failure (failure to operate and inadvertent operation) are taken into account in the proposed model. The model also considers routine test inspections, the self-checking facility of digital relays, and also common cause failures of protective devices and protected components. Numerical studies show the influence of human errors on protection system reliability.

Reliability evaluation of protection devices in electrical power systems

Electrical power is transmitted and distributed by a complex and integrated network which is exposed to various types of faults. These faults are usually short-circuits which occur between phases and between phases and earth. To protect the system against these faults, protection systems, based on automatic relay devices, are incorporated into the power system. This paper discusses the principles of these relay systems and describes techniques that have been developed in order to evaluate the reliability of the devices. The paper also discusses the principles of monitoring and self-checking within the relay to reduce the probability of an undetected dormant failure. All the concepts and techniques are illustrated by the analysis of a typical distance protection relay.