scholarly journals Instantaneous Circuit Breaker Settings for the Short-Circuit Protection of Three-Phase 480-, 600-, and 1040-V Trailing Cables

1981 ◽  
Vol IA-17 (4) ◽  
pp. 369-376 ◽  
Author(s):  
George Fesak ◽  
William S. Vilcheck ◽  
William J. Helfrich ◽  
David C. Deutsch
Author(s):  
N M Nor ◽  
N S Zemri ◽  
S A Daud ◽  
T Ibrahim ◽  
H Daud

Most electrical appliances require continuous power supply. For domestic use, crucial appliances such as refrigerator, aquarium and alarm system highly depend upon the continuity of power supply. However, if they are left without electricity due to power outage or blackouts caused by internal or external disturbance, the discontinuity of power supply could be a critical issue to some involving party. Blackouts may be due to short circuit, fault or the overloading of electricity mains. During power outage, Residual Current Device (RCD) detects fault currents from live to the neutral wire within circuit and will trip to prevent shock. This circumstance can increase safety when a house is left unoccupied. Be that as it may, the power will remain switched off until manually reset by man. Thus, this paper presented a new concept of Three-Phase distribution box system in order to overcome tripping problem. This system will be able to identify and isolate the fault using measurement of current flow into each Miniature Circuit Breaker (MCB) of appliances and current flowing out from each of the load. The measured current value will be compared and the maximum allowable difference is 30mA. If the current difference exceeds the maximum limit then the fault MCB will be detected. Hence RCD will be automatically close the circuit after determining the fault location via the motor operation to make sure of power stability and evade any property loss.


2020 ◽  
Vol 4 (2) ◽  
pp. 53-59
Author(s):  
Cilvia Calnela ◽  
Suyitno ◽  
Imam Arif Raharjo

This study aims to determine the difference in short circuit current with manual calculation and ETAP 12.60 Simulation  in to know the suitability of capacity circuit breaker Substasion 150/20 kV at Gandul. The used method is qualitative descriptive method. The subject that will be studied is short circuit on the substation 150/20 kV Gandul Cinere. The research was conducted by using is manual calculation and software ETAP 12.60 simulation. The results obtained is differences of the short circuit current is not significant between the manual calculation and software ETAP 12.60 simulation in three conditions include 0.572% for the conditions of short circuit fault of one phase to ground, 0.884% for the conditions of short circuit fault of phase to phase and last 0.884% for the short circuit fault of three phase. Furthermore, the result of the calculation of the short circuit current will be used as an indicator of a determinant of the suitability of the capacity circuit breaker substation 150/20 kV at Gandul , obtained that a comparison of the rating circuit breaker installed (existing) is great against the result of the election of the rating circuit breaker base on manual calculation. So it can be concluded that the circuit breaker beinstalled on the substation 150/20 KV at Gandul, has a capacity that suits your needs and still fit for use. ABSTRAK Penelitian ini bertujuan untuk mengetahui perbedaan besar arus hubung singkat antara perhitungan manual dan simulasi ETAP Power Station 12.6 serta untuk mengetahui kesesuaian kapasitas pemutus tenaga GI Gandul 150/20 kV. Metode yang digunakan adalah deskriptif kualitatif. Subjek pada penelitian ini adalah arus hubung singkat pada Gardu Induk 150/20 kV Gandul Cinere. Penelitian dilakukan menggunakan perhitungan manual dan simulasi software ETAP Power Station 12.6. Hasil penelitian diperoleh bahwa perbedaan hasil arus hubung singkat yang tidak signifikan antara perhitungan manual dan simulasi software ETAP Power Station 12.6 dalam tiga kondisi meliputi 0.572% untuk kondisi gangguan hubung singkat salah satu fasa ketanah, 0.884% untuk kondisi gangguan arus hubung singkat fasa ke fasa dan terakhir 0.884% untuk gangguan arus hubung singkat tiga fasa. Selanjutnya, hasil perhitungan arus hubung singkat tersebut akan digunakan sebagai indikator penentu kesesuaian kapasitas pemutus PMT (Circuit Breaker) GI Gandul 150/20 kV, diperoleh bahwa perbandingan rating pemutus PMT yang terpasang (existing) lebih besar terhadap hasil pemilihan rating pemutus PMT berdasarkan perhitungan manual. Sehingga dapat disimpulkan bahwa pemutus tenaga yang terpasang pada di GI Gandul 150/20 kV memiliki kapasitas yang sesuai dengan kebutuhan dan masih layak digunakan.


Author(s):  
Karan S Belsare ◽  
Gajanan D Patil

A low cost and reliable protection scheme has been designed for a three phase induction motor against unbalance voltages, under voltage, over voltage, short circuit and overheating protection. Taking the cost factor into consideration the design has been proposed using microcontroller Atmega32, MOSFETs, relays, small CTs and PTs. However the sensitivity of the protection scheme has been not compromised. The design has been tested online in the laboratory for small motors and the same can be implemented for larger motors by replacing the i-v converters and relays of suitable ratings.


2020 ◽  
Vol 178 ◽  
pp. 01060
Author(s):  
A V Kuznetsov ◽  
D S Aleksandrov ◽  
Y P Yurenkov

This paper shows that successful switching of extremely high short-circuit currents I> 50 kA can be achieved by joint operation of a liquid-metal self-resetting current limiter and a circuit breaker connected in series. The type NFU-225 device from Mitsubishi was taken as an example. The time-current characteristic of joint operation of a liquid-metal self-resetting current-limiting device and a circuit breaker was compiled. However, further in the article physical processes occurring in a liquid-metal self-resetting current limiter with a complete transformation of fusible unit are considered. The result of work is modelling of operation of liquid-metal fuses when overcurrents are switched off based on the pilot studies obtained by the Japanese scientists. It is proposed to simulate the break process not at every time moment, but at specific time moments (reference points). At other time moments, current and voltage should be considered as approximately linearly changing characteristics. The work of current limiter can be represented by three stages: the pre-arc, the main arc and the final arc. If the current density is less than 1000 A/mm2, then the pre-arc operation stage of the current limiter includes the following sections for heating the fusible unit: primary heating to the melting temperature; melting and its transition to liquid state; secondary heating to evaporation temperature; evaporation of fusible unit.


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