Comparative Study of Calculation Methods for Short-Circuit Currents in Low-Voltage Networks with Asynchronous Motors

2021 ◽  
Author(s):  
Abdullo Majidov ◽  
Alisher G. Kayumov ◽  
Nozim Kholov
Keyword(s):  
Comparative Study ◽  
Low Voltage ◽  
Short Circuit ◽  
Calculation Methods ◽  
Asynchronous Motors ◽  
Short Circuit Currents

scholarly journals Thyristor Arc Eliminator for Protection of Low Voltage Electrical Equipment

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2749 ◽  
Author(s):  
Karol Nowak ◽  
Jerzy Janiszewski ◽  
Grzegorz Dombek
Keyword(s):  
Lower Cost ◽  
Low Voltage ◽  
Short Circuit ◽  
Electrical Equipment ◽  
Power Network ◽  
System Operation ◽  
Test Circuit ◽  
Wide Range ◽  
Short Circuit Currents ◽  
Electrical Apparatus

The paper presents the layout of two opposing thyristors working as an Arc Eliminator (AE). The presented solution makes it possible to protect an electrical apparatus against the effects of an arcing fault. An Arc Eliminator is assumed to be a device cooperating with the protected apparatus. Thyristors were used because of their speed of operation and a relatively lower cost compared to other semiconductors with the same current-carrying capacity. The proposed solution, as one of the few currently available, makes it possible to eliminate the fault arc—both at short-circuit currents and current values to which overcurrent protections do not react. A test circuit was designed and made to study the effectiveness of the thyristor arc eliminator. A series of tests was carried out with variable impedance in the arc branch, including the influence of circuit inductance on arc time. It was found that the thyristor arc eliminator effectively protects devices powered from a low voltage power network against the effects of a fault or arc fault. The correctness of system operation for a wide range of impedance changes in the circuit feeding the arc location was demonstrated.

Computation of Radial Electromagnetic Forces on Power Transformer LV Windings due to Short-Circuit Currents

2013 ◽  
Vol 732-733 ◽  
pp. 1069-1073 ◽  
Author(s):  
Han Bo Zheng ◽  
Jin Hua Han ◽  
Wei Wang ◽  
Xiao Gang Li ◽  
Yu Quan Li
Keyword(s):  
Mechanical Stress ◽  
Case Studies ◽  
Calculation Method ◽  
Electromagnetic Force ◽  
Radial Direction ◽  
Low Voltage ◽  
Power Transformer ◽  
Short Circuit ◽  
Leakage Flux ◽  
Short Circuit Currents

The short-circuit electromagnetic force in radial direction induces critical mechanical stress on a power transformer. In this paper, the radial short-circuit forces which are exerted on transformer low voltage (LV) windings are investigated. Firstly, the mechanisms of leakage flux and short-circuit electromechanical forces in transformer coils are analyzed. Afterwards, based on IEC standards followed by short-circuit tests, calculations of radial short-circuit forces and evaluations of the ability to withstand short currents in LV windings are developed. The case studies and comparisons with improved measures show that the evaluation and calculation method is feasible and effective, and this method also offers three useful ways to strengthen the ability to withstand short-circuit currents for transformer windings.

Sign in / Sign up

Export Citation Format

Share Document