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Main parts of a circuit breaker 

Main parts of a circuit breaker 

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Let-through energy (Joule heat) is an important factor in proper protection of electrical installations and devices. Studies were preformed during which the relationship between amount of energy and phase angle of short-circuit current was examined. Typically used miniature circuit breaker was utilized as a protective device. Scilab software for nu...

Context in source publication

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... CIRCUIT BREAKERS CONSTRUCTION Figure 1 shows schematically the main parts of a low voltage circuit breaker and its four essential functions [1]: -circuit-breaking components, comprising the fixed and moving contacts and the arc-dividing chamber, -latching mechanism which becomes unlatched by the tripping device on detection of abnormal current conditions, this mechanism is also linked to the operation handle of the breaker, -trip-mechanism actuating device: either: a thermal-magnetic device, in which a thermally-operated bi-metal strip detects an overload condition, while an electromagnetic striker pin operates at current levels reached in short-circuit conditions, or  an electronic relay operated from current transformers, one of which is installed on each phase, -space allocated to the several types of terminal currently used for the main power circuit conductors. Use of miniature circuit breakers (MCB) as protection devices for electrical installations is required by Polish law [2]. ...

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Joule's heat (let-through energy) is an important factor in proper protection of electrical installations and devices. Studies were preformed during which the relationship between amount of energy and phase angle of short-circuit current was examined. Typically used miniature circuit breaker was utilized as a protective device. Scilab software for...

Citations

... Należy zauważyć,że dla kąta fazowego 120 • , w czasie pomiaru, obserwowane były zarówno krótkie jak i długie czasy trwania zwarcia. Z tego powodu dla tego kąta występują duże zróżnicowania wartości całki Joule'a od 61 A 2 s do 216 A 2 s [97,98]. ...
Thesis
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Presented for review and public defense the doctoral dissertation titled ,,Electrode processes in low voltage alternating current relays'' consists of nine chapters, supplemented with bibliography, and list of tables and figures, and consists of 197 pages. In the first chapter in a generalized manner presents the problem. These issues relate to the impact of selected electrode processes on contact system of electromagnetic relays. The second chapter presents the categorization of electrical connectors with the classification of relays. The basics of packaging and operating rules are described. It also presents rules for the selection of overload protection. The next chapter explains the materials used for the contact rivets. Describes general properties of materials used for rivets, with special emphasis on those used in relays. The fourth chapter is devoted to the issue of contact resistance. Described is a basic, applied analytical model. Pondering the question connected with the analytical method for determining the value of the resistance and how to measure it. In the next, fifth chapter, discussed in detail are selected electrode processes. The chapter describes the issues associated with mechanical erosion related to the interaction of the relay contacts. It also presents process of erosion of the electrode surface resulting from switching operating and short-circuit currents. Also, it describes the phenomena of heating electrodes relays the flow of operating currents and short-circuit. A characterization is made of the electrodynamic force present during the flow of short-circuit currents. In the sixth chapter the purpose of the thesis and doctoral dissertation is described. It also describes the scope of work for the analysis. In the seventh chapter there is presented the Authors test set-up used to study the processes described. Its principle of operation and electrical diagram. An analysis of errors in the range of measurements of contact resistance is described. Also the selected equipment, which also was used in time research is shown. The eighth chapter contains a description of the test results and calculations and analyses. Characterized by the interaction of individual electrode processes on relay contacts and observed changes on the contact surface. The influence of the contact resistance value is shown. Electrical contacts heating process was calculated. The analysis of the occurrence of contact welding is done as well. In the last, ninth chapter, the conclusions of studies of electrode processes, their impact on the value of contact resistance and recommendations for the design and operation of low-voltage relays are presented.
... Obwód ten miał charakter czysto rezystancyjny (cos φ = 0,99). Parametr ten jest istotny, ponieważ zarówno czasy zadziałania, jak i całka Joule'a wyłączania jest zależna od kąta fazowego napięcia w chwili wystąpienia zwarcia [5,7]. Na podstawie przedstawionych przebiegów można zauważyć, że rzeczywisty czas zadziałania w przypadku każdego z zastosowanych aparatów zabezpieczających był krótszy niż 10 ms. ...
... Również inne badania potwierdziły, że czas ten często nie przekracza właśnie jednego półokresu sinusoidy napięcia zasilającego [6]. Przeważnie wyłączenie następuje w czasie nie dłuższym niż 15 ms [5,7]. W tablicy 3 przedstawiono całki Joule'a wyłączenia oraz wartości prądu szczytowego dla każdej próby. ...
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