Degui Chen

Xi'an Jiaotong University, Ch’ang-an, Shaanxi, China

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Publications (36)19.51 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A 3-D transient finite-element method to analyze the short-time withstand current for an air circuit breaker (ACB) is presented. The cylindrical contact bridge is adopted to describe the current constriction between the movable and fixed contacts, and then considering the influence of the eddy current, the resistivity and thermal conductivity variations with the temperature, and the coupled calculation of the corresponding electromagnetic field and thermal field can be performed to evaluate the short-time withstand current capability. To verify the calculation method and results based on the ACB model, relevant experiments are also conducted through measuring the temperature of two points on the contacts with the thermocouple. It demonstrates that the proposed method can be used to optimize the design of ACBs.
    IEEE Transactions on Power Delivery 10/2013; 28(4):2610-2615. DOI:10.1109/TPWRD.2013.2265328 · 1.66 Impact Factor
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    ABSTRACT: Linkage transfer phenomenon, which exists in the opening process of the operating mechanism of the molded case circuit breaker MCCB, is introduced. The influence of the linkage transfer position on the behavior of the mechanism is analyzed. According to the analysis result, the linkage transfer position of an actual operating mechanism is improved with virtual prototype technology software ADAMS. Simulation and experiment results show that after improvement, the opening time of the mechanism is shortened by about 1 ms. Short-circuit tests demonstrate that the operating mechanism with its linkage transfer position improved is helpful for enhancing the interruption performance of MCCB while breaking the low-current faults.
    IEEE Transactions on Power Delivery 02/2011; 26(1-26):222 - 227. DOI:10.1109/TPWRD.2010.2059049 · 1.66 Impact Factor
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    ABSTRACT: A 2-D magnetohydrodynamic (MHD) arc model is developed to simulate the influence of the venting configuration on air arc plasma motion in a low-voltage circuit breaker. It is demonstrated that the fully closed back venting is helpful to accelerate the arc motion due to the propagation of a pressure wave. Side- and central-type front-venting configurations are also compared. It is found that the arc velocity is higher, and yet the probability of reignition is increased for the central-type front venting, as a consequence of differences in the current density distribution. Using an arc chamber with different venting configurations, short-circuit interruption experiments are carried out. These verify the arc reignition trends predicted in the simulations.
    IEEE Transactions on Plasma Science 10/2010; DOI:10.1109/TPS.2010.2049382 · 0.95 Impact Factor
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    ABSTRACT: The dynamic characteristics are the key issues in the optimum design of a permanent magnetic actuator (PMA). A new approach to forecast the dynamic characteristics of the multilink PMA is proposed. By carrying out further developments of ADAMS and ANSOFT, a mathematic calculation model describing the coupling of mechanical movement, electric circuit and magnetic field considering eddy current effect, is constructed. With this model, the dynamic characteristics of the multilink PMA are calculated and compared with the experimental results. Factors that affect the opening time of the multilink PMA are analyzed with the model as well. The method is capable of providing a reference for the design of the PMA.
    IEICE Transactions on Electronics 09/2010; 93-C:1404-1410. DOI:10.1587/transele.E93.C.1404 · 0.33 Impact Factor
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    ABSTRACT: Similarities and differences of the thermal analysis issues between the intelligent and general AC contactors are analyzed. Heat source model of the magnet system is established according to the unique control mode of the intelligent AC contactor. Linking with the features common of the two kinds of contactors, the extension of the thermal analysis method of the general AC contactor to the intelligent AC contactor is demonstrated. Consequently, a comprehensive thermal analysis model considering heat sources of both main circuit and magnet system is constructed for the intelligent AC contactor. With this model, the steady-state temperature rise of the intelligent AC contactor is calculated and compared with the measurements of an actual intelligent AC contactor.
    IEICE Transactions on Electronics 09/2010; 93-C:1424-1430. DOI:10.1587/transele.E93.C.1424 · 0.33 Impact Factor
  • Degui Chen, Xingwen Li, Ruicheng Dai
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    ABSTRACT: Gas flow in arc quenching chamber has an important effect on the interruption capability of low voltage circuit breakers. In this paper, based on a simplified model of arc chamber with a single break, which can be opened by the electro-dynamics repulsion force automatically, the effect of different vent configurations including middle vent and side vent on the interruption performance is investigated. First, the experiments are carried out to compare the different performance in the interruption process between middle vent type and side vent type. In addition, according to the experimental model, a 3-D magneto-hydrodynamic model was developed by adapting and modified the commercial computational fluid dynamics software FLUENT. The simulation results show the same trend in arc motion as explained in the experimental conclusions in theory.
    IEICE Transactions on Electronics 09/2010; 93-C:1399-1403. DOI:10.1587/transele.E93.C.1399 · 0.33 Impact Factor
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    ABSTRACT: Research on the interruption process of control and protective switch devices (CPS) is helpful for improving its current-limiting performance. Three different structures of the main contact system are proposed and experimentally investigated on their influence on CPS's interruption performance first. Then, a calculation model that enables us to simulate the interruption process of a low-voltage apparatus with a complex mechanical structure is realized by carrying out the second development of ADAMS, in which a set of differential equations describing the coupling of complex mechanical movements, electric circuits, magnetic fields, and dynamic mathematic arc models is constructed. With this model, further investigations on the interruption process, arc movement, and arc characteristic variation of CPS with the three main contact systems are carried out. The improvement mechanism of the current-limiting performance of CPS using an arc run-on plate is especially analyzed with the calculation model.
    IEEE Transactions on Power Delivery 08/2010; 25(3-25):1556 - 1563. DOI:10.1109/TPWRD.2010.2047029 · 1.66 Impact Factor
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    ABSTRACT: This paper presents an accurate and systematic method to model the equivalent circuit of pulse generator in the electrical fast transients/burst test (EFT/B). Firstly, a new analytical expression is presented to express the generator's charging and discharging process under open-condition (1000-Omega), which all its coefficients are determined according to the output waveform specified by the manufacturer. And then, with adoption of the step source, the transfer function of the pulse forming network in Laplace domain is deduced, which is ready for the network synthesis. Based on above discussion, the parameterized method and the technique of constant-resistance are adopted for the network synthesis. Finally, the equivalent circuit is renormalized and improved to meet the specification under matching-condition (50-Omega). In this way, the equivalent circuit of EFT/B generator is obtained and can be adjusted conveniently to satisfy the different manufacturers. The PSPICE simulation with a certain load is validated by measurement.
    IEICE Transactions on Electronics 08/2009; 92-C(8):1052-1057. DOI:10.1587/transele.E92.C.1052 · 0.33 Impact Factor
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    ABSTRACT: According to a new kind of permanent contactor, this paper analyses the dynamic behavior of the contactor with and without current-feedback system. And it presents a method to obtain the dynamic characteristics of the contactor with current-feedback system. The experiments prove that the method is correct. Then, it compares the contactor without current-feedback system with the one with current-feedback system. The result shows that the contactor with current-feedback system can avoid this flaw of the contactor without current-feedback system.
    IEICE Transactions on Electronics 08/2009; 92-C(8):1040-1044. DOI:10.1587/transele.E92.C.1040 · 0.33 Impact Factor
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    ABSTRACT: This paper is devoted to study the influence of ferromagnetic material on arc behavior in low voltage electric apparatus. With the self-programmed interface, one 2-D magnetohydrodynamic arc model can be developed based on the commercial software FLUENT and ANSYS, to study the vapor of ferromagnetic material effects on air arc behavior. Then, the corresponding interruption experiments are performed to verify the simulation qualitatively. It demonstrates that the vapor of ferromagnetic material is disadvantageous to arc interruption characteristics. In addition, the influence of the size of the ferromagnetic splitter plate on arc motion is simulated. It shows that the bigger splitter plate may accelerate the arc motion.
    IEEE Transactions on Plasma Science 04/2009; DOI:10.1109/TPS.2008.2010940 · 0.95 Impact Factor
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    ABSTRACT: Gas flow in arc quenching chamber has an important effect on the interruption capability of low voltage circuit breakers. In this paper, based on a simplified model of arc chamber with a single break, which can be opened by the electro- dynamics repulsion force automatically, the effect of different vent conditions including middle venting and side venting on the interruption performance is investigated. First, the effect of the different size of side vent type on the chamber pressure, and interruption capability were studied experimentally. It demonstrates that the smaller vent size is, the higher pressure and better the interruption performance will be, but when the vent size smaller than a certain proportion, the arc will re-ignite and when the vent size larger than a certain proportion, the arc will also re-ignite. Experiments are carried out to compare the different performance in the interruption process between middle vent to be conventional vent type and side vent type. In addition, according to the experimental model, a 3-D magneto- hydrodynamic model was developed by adapting and modified the commercial computational fluid dynamics software FLUENT. The simulation results show the same trend in arc motion as explained in the experimental conclusions in theory.
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    ABSTRACT: The gas-puffer effect has important effects on the interruption capability of a molded case circuit breaker (MCCB). In this paper, on the basis of a simplified model of an arc chamber with a single break, the effect of back-volume of an arc-quenching chamber on arc behavior in an MCCB is investigated. Firstly, using a 2-D optical-fiber arc-motion measurement system, experiments are performed to study the effect of back-volume on the arc-motion and gas pressure in an arc-quenching chamber. We demonstrate that the lower back-volume of the arc-quenching chamber is, the higher the pressure and the better the arc motion will be. Then, corresponding to the above experiments, the gas pressure inside the arc-quenching chamber is calculated using the integral conservation equation. The simulation results are consistent with the experimental results.
    IEICE Transactions on Electronics 08/2008; DOI:10.1093/ietele/e91-c.8.1261 · 0.39 Impact Factor
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    ABSTRACT: In the optimum design of AC contactors, it is important to analyze the dynamic behavior. Moreover, movable contact and core bounces have remarkable effect on the lifetime of contactors. According to a new kind of contactor with feedback controlled magnet system, this paper builds two different sets of periodically inter-transferred equations to obtain the dynamic characteristics of the contactor. The equations describe the coupling of the electric circuit, electromagnetic field and mechanical system taking account of the influence of friction. Then, the paper gives an optimum design to the dimension and the duty ratio of the contactor' pulse modulated wave (PWM) under different exciting, and proves, by experiment and simulation, that the bounce time of the contactor working in the optimized duty ratio is much less than that of the general AC contactors.
    IEICE Transactions on Electronics 08/2008; DOI:10.1093/ietele/e91-c.8.1273 · 0.39 Impact Factor
  • Xingwen LI, Degui Chen
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    ABSTRACT: The precision of magnetic field calculation is crucial to predict the arc behavior using magnetohydrodynamic (MHD) model. A integrated calculation method is proposed to couple the calculation of magnetic field and fluid dynamics based on the commercial software ANSYS and FLUENT, which especially benefits to take into account the existence of the ferromagnetic parts. An example concerning air arc is presented using the method.
    IEICE Transactions on Electronics 08/2008; DOI:10.1093/ietele/e91-c.8.1228 · 0.39 Impact Factor
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    ABSTRACT: This paper simulates the dynamic behavior of the operating mechanism of ACB, and analyzes factors influencing the mechanism's operating time. First, it builds a dynamic model for the mechanism with virtual prototype technology. Experiment validation is carried out to prove the correctness of the model. Based on this model, it puts emphasis on analyzing the influence of electro-dynamic repulsion force on the operating time of the mechanism. Simulation and experimental results show that after adding electric repulsion force to the model, the operating time is shortened about 1.1 ms. Besides the repulsion force, other influencing factors including the stiffness of opening spring, locations of every key axis, mass and centroidal coordinates of every mechanical part are analyzed as well. Finally, it makes an optimum design for the mechanism. After optimization, the velocity of operating mechanism is improved about 6.7%.
    IEICE Transactions on Electronics 08/2008; DOI:10.1093/ietele/e91-c.8.1280 · 0.39 Impact Factor
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    ABSTRACT: Short-time withstand current is one of the crucial nominal parameters in air circuit breaker. A numerical method to evaluate the short-time withstand current is proposed. Cylindrical current carrying bridge is introduced to describe the contact spot between movable and fixed contacts. Taking into account the action of ferromagnetic splitter plates, the variation of the conductor properties with temperature and the variation of contact spot radius with the electro-dynamic repulsion force, a transient finite element calculation model is developed by coupling the electromagnetic field and thermal field. The loaded short circuit current is considered as the short-time withstand current once the highest temperature is near to the melting point of the contact material. It demonstrates that the method is useful to evaluate the performance of the air circuit breaker.
    IEICE Transactions on Electronics 08/2008; DOI:10.1093/ietele/e91-c.8.1292 · 0.39 Impact Factor
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    ABSTRACT: To predict the thermal behavior of switchgear quickly, the Thermal Network Finite Difference Analysis method (TNFDA) is adopted in thermal analysis of AC contactor in the paper. The thermal network model is built with nodes, thermal resistors and heat generators, and it is solved using finite difference method (FDM). The main circuit and the control system are connected by thermal resistors network, which solves the problem of multi-sources interaction in the application of TNFDA. The temperature of conducting wires is calculated according to the heat transfer process and the fundamental equations of thermal conduction. It provides a method to solve the problem of boundary conditions in applying the TNFDA. The comparison between the results of TNFDA and measurements shows the feasibility and practicability of the method.
    IEICE Transactions on Electronics 08/2008; DOI:10.1093/ietele/e91-c.8.1286 · 0.39 Impact Factor
  • Source
    Xingwen Li, Degui Chen, Yi Wu, Ruicheng Dai
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    ABSTRACT: A two-dimensional arc magnetohydrodynamic model is presented to study the effects of metallic vapour and gassing material on air switching arc motion based on different mixture plasma properties (pure air, 99% air–1% Cu, 99% air–1% Ag, 99% air–1% Fe, 90% air–10% PA6). It demonstrates that metallic vapours may cool the arc central region and reduce the arc motion velocity, and iron vapours have the strongest action compared with copper and silver vapours; the gassing material may improve the arc motion velocity. In addition, the effect of the net emission coefficient model and the grey body radiation model on the calculation results for pure air arc motion is compared. To verify the simulation results partially, using the integrated imaging diagnostics system, experiments are carried out to measure the average velocity of arc motion with one model chamber.
    Journal of Physics D Applied Physics 11/2007; 40(22):6982. DOI:10.1088/0022-3727/40/22/019 · 2.52 Impact Factor
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    ABSTRACT: A dynamic model of the operating mechanism for a low voltage molded case circuit breaker (MCCB) was built based on virtual prototype technology, and then a test was done to verify this model, which showed that simulation results of virtual model were in agreement with test results of real prototype. After adding electric repulsion force to model, the operating time of mechanism was shortened about 2 ms. Using this model, besides the repulsion force, the factors including the stiffness of opening spring, the shape of mechanism parts affected the dynamic characteristics of operating mechanism are analyzed as well, and it also indicates that centroidy coordinates of trip has the greatest influence on angular velocity of operating mechanism. Selecting x and y coordinates of mechanism axes as the design variables, after optimum design, average angular velocity of operating mechanism has risen 15.3%.
    Electrical contacts - 2007, the 53rd ieee holm conference on; 10/2007