63 research outputs found
Numerical Analysis of Thermal Behaviour of DC Fuse
No full textOne of the very well-known protections for electrical apparatus against overloads or short circuits is the fuse. It can be used to protect both AC or DC electrical installations and it has also proven its effectiveness in the protection of different loads. This paper describes a three-dimensional model of a DC fuse with two different types of fuselink notches: circular and rhombic. The obtained 3D thermal model can be used to investigate the thermal behaviour of DC fuses in both steady-state and transient conditions at different values of overloads or short circuits. With the aim to validate the proposed 3D thermal model, a series of experimental tests have been achieved. The thermal simulated values are in good concordance with the experimental results (a relative error less than ±6% has been obtained between experimental and simulation data)
Thermal Analysis of Busbars from a High Current Power Supply System
No full textCopper busbar technology is widely used with the aim to achieve electrical connections with power distribution systems because of their flexibility and compactness. The thermal analysis takes into account the heat conduction and convection of a copper busbar system used to supply a test bench with high currents in order to check the electro-thermal behaviour of power circuit breakers during overload and short circuit conditions. This paper proposes a mathematical model for busbars used within a high current power supply. The obtained thermal model can be used to analyse the thermal behaviour of busbars in steady-state conditions at different values of the electric current, cross-section and length of the busbar. Also, the mathematical model allows to calculate the temperature distribution along the busbar at different values of the contact resistances at junction points with other conductors. There is a good correlation between calculated, simulated and experimental results
Temperature Distribution of HBC Fuses with Asymmetric Electric Current Ratios Through Fuselinks
No full textIn many industrial applications high breaking capacity (HBC) fuses are used to protect electrical installations against overcurrents, especially in the power distribution network. At high rated current, HBC fuses have more parallel fuselinks mounted inside. The technological and mounting processes of the fuselinks inside the fuse results in an asymmetrical current distribution through the parallel fuselinks. In this article a model of a high breaking capacity fuse using two parallel fuselinks is proposed. The influence of electric current, cross-section of the notches, distance between notches and current imbalance through fuselinks on the maximum temperature rise of both fuselinks, has been investigated. Also, a 3D thermal model for the same HBC fuse has been developed. The temperature spread into the fuse and its elements has been obtained. In order to prove the validity of the mathematical and 3D model different tests have been considered. The experimental, simulation and computed results give similar values and it results that this model can also be used for fuses with many parallel fuselinks and it permits the design of new fuse elements with optimal thermal distribution
Thermal Analysis of Power Semiconductor Device in Steady-State Conditions
No full textElectronic devices can be damaged in an undesirable manner if the junction temperature achieves high values in order to cause thermal runaway and melting. This paper describes the mathematical model to calculate the power losses in power semiconductor devices used in bidirectional rectifier which supplies a resistive-inductive load. The obtained thermal model can be used to analyse the thermal behaviour of power semiconductors in steady-state conditions, at different values of the firing angle, direct current, air speed in the case of forced cooling, and different types of load. Also, the junction and case temperature of a power thyristor have been computed. In order to validate the proposed mathematical model, some experimental tests have been performed. The theoretical values are in good concordance with the experimental data and simulated results
Considerations About Controlled Capacitors
No full textConsiderations About Controlled CapacitorsA new type of thermal controlled capacitor has been developed and studied. The capacitor non-linearity depends on the control parameter — temperature. At constant temperatures, the charge versus voltage curve is non-linear and has thermal inertia. Actually, it is a new method to modify the capacitors' capacitance using the thermal field as a command parameter and brings new technical solutions for protection of electrical equipment.</jats:p
THE INFLUENCE OF BUSBARS CONNECTION ON FUSELINK TEMPERATURE AT FAST FUSES
No full textThe paper, based on three-dimensional thermal modelling and simulation finite element method software package, presents a comparison between the thermal behaviour of a fast fuse without busbar terminals and the one with these busbars mounted on it. The maximum fuselink temperature is lower in the second case when the thermal model had taken into consideration the busbar connections, actually, the real situation. Also, a thermal analysis for different type of load variations has been done in both cases of the fast fuse geometry with and without busbar terminals
3D Thermal Analysis of a Power Supply Busbar Structure
No full textBusbar technology is more and more used to realize connections within power supply systems in answer to the need of compactness. The integrated problem on heat conduction and radiation-convective heat exchange describes the temperature regime in current conductors and current carrying busbars of power electrical apparatus such as circuit breakers or high breaking capacity fuses. Beside steady-state conditions, the transient thermal regime of busbar has an important influence upon whole power supply system from thermal behaviour point of view. Hence, a 3D thermal analysis of a power system including fuse, low voltage circuit breaker and busbars connections, using a specific software package based on Finite Element Method, has been done. From 3D thermal modelling and simulations, the thermal transient impedance for the busbar has been computed. This allows a better correlation between protection characteristics of the fuse and circuit breaker and busbar design.</jats:p
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