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Wyszukujesz frazę "time-current characteristic" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Uncertainty of the characteristics of electrical devices based on the measurements of time-current characteristics of MV fuses
Autorzy:
Daszczyński, T.
Pochanke, Z.
Kolimas, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/200192.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
time-current characteristic
MV fuse
approximation of measurement results
fuse element
statistics
Opis:
Functional properties of some electrical devices are expressed in the form of a dependence between parameters defining a given aspect of device duty or work circumstance (e.g. breakdown voltage): contacts distance for a circuit breaker, current (voltage for voltage limiters or reaction time), and load current for over current protection. Such characteristics are obtained experimentally, usually in a set of test series, each performed with a fixed independent parameter. Results of each series generate sets of data for estimation of statistical properties of a dependent parameter: distribution, expected value, variance and confidence interval. These statistics concern one point of the tested characteristic, so to get data of it as a whole, that would satisfy the needs for designing an electrical system, a large number of tests can be necessary. The way to reduce the number of tests may consists in: defining the characteristic not as a series of points, but as an analytical function with some specific parameters. This can be combined with aggregation of results of all tests in one set of data for estimation of statistical properties of the mantioned parameter. This paper presents an application of the above approach to tests of time-current characteristics of fuses.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 4; 751-757
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A New Approach on Improving The Operation of Over-Current Relays in 6kV Mining Grids of QuangNinh, VietNam
Autorzy:
Bun, Ho Viet
Thanh, Le Xuan
Powiązania:
https://bibliotekanauki.pl/articles/24200705.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
over-current relays
open-pitch mines
instantaneous time characteristic
false trip
Time Multiplayer Setting
Opis:
Over-current relays (OCR) are the most popular protecting devices utilized in 6kV mining grids of open-pitch mines, QuangNinh province, VietNam. Depending on time of operation of OCR, there are many operating mode catergorized as: Instantaneous OCR, Inverse time OCR, Inverse definite minimum time (IDMT) OCR, Very invese relays, Extremely Inverse relays. Nowaday, to give protection against: Phase faults, Earth faults, Winding faults (in transformer), most of mining companies using Over-current relays with instantaneous characteristic. This charactersitic has the following important features: i) Operates in a definite time when current exceed relay’s pick-up/setting up values, ii) Relay’s operation is mainly relied on current magnitude, iii) Operating time is constant, iv) There isn’t any intentional time delay, v) The operating currents are progressively increased for the other relays when moving towars the source. Apart from many advantages, there is a significant disavantage of the relays’s operation: when there are faults at the beginning of feeders, OCR with instantaneous characteristic usually has a big-time tripping. Moreover, sometimes there are false trip of OCR because of improper set-up. In this study, an offline method is proposed with simulation in ETAP software to overcome these issues. With Gurobi-Optimizer application, an algorithm for identifying Time Multiplayer Setting (TMS) will be employed to generate inversetime characteristic/inverse definite minimum time charactersitic for improving the performance of over-current relay with better discriminative tripping. The proposed method is simulated on ETAP with a 6kV sample skeleton distribution network (in QuangNinh province of VietNam). The demonstrating results are: the prevention of false trip of OCR and the operating time of OCR is reduced.
Źródło:
Inżynieria Mineralna; 2023, 2; 29--38
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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