جستجوی مقالات مرتبط با کلیدواژه « hysteresis curve » در نشریات گروه « برق »

In this paper, inrush current reduction in power transformers has been analyzed and a new strategy is proposed for effective reduction of this current. Residual flux has an important role in the amplitude of inrush current in power transformers. Therefore, first, analytical method has been introduced for estimating residual flux using the information during deenergizing. In the next step, another method has been introduced using residual inductance concept for estimating residual flux when there is no access to the information during deenergizing. Considering some limitations in this method and also possessing the required information and the way of deenergizing in most cases, a new strategy is proposed to mitigate the inrush current. In the proposed strategy, instead of estimating the residual flux, its value is fixed and used in energizing process to reduce inrush current. Additionally, the proposed strategy can be used in different types of power transformers and connections with no need to the neutral point. Simulation results exhibit effective reduction in inrush current using the proposed strategy.

Considering the importance of controlling the behavior of structures against lateral loads such as earthquakes, the use of dampers in structures is needed to control and improve the structural responses. In this study, the effect of rotational, viscous, and TADAS frictional damper on the behavior and responses of the 8-story steel frame structure with residential use in Mashhad was investigated. These structures were compared in two cases equipped with a damper and without a damper. Seismic earthquake history was used to apply earthquake force. The history of the earthquakes used was obtained by squared squares method and was matched with the soil type 3 soil. Then each of the structures was studied under the analysis of nonlinear time history in SAP2000 software. In this study, the maximum story displacement, the basic shear and the hysteresis curve of each floor were evaluated to determine the effect of dampers on the behavior of the structures. The results of the investigations show that in the study of the structure equipped with the damper, the specifications of the dampers should be based on the behavior of each floor and the adjustment of the damper according to the overall behavior of the structure is inappropriate.