scholarly journals Electrodynamic Contact Bounce Induced by Fault Current in Low-Voltage Relays

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3926
Author(s):  
Andrzej Ksiazkiewicz ◽  
Grzegorz Dombek ◽  
Karol Nowak ◽  
Jerzy Janiszewski
Keyword(s):  
Low Voltage ◽  
Threshold Value ◽  
Fault Current ◽  
Contact Materials ◽  
Fault Currents ◽  
Current Threshold ◽  
Protection Devices ◽  
Electromagnetic Relays ◽  
Contact Welding ◽  
Selection Of

Due to fault currents occurring in electrical installations, high electromagnetic force values may be induced in current paths of low-voltage electromagnetic relays. This force may lead to an electromagnetic bounce that will further result in an electric arc ignition between contacts, and under some circumstances, it will result in contact welding. For the proper exploitation of relays, the threshold value of the maximum current, and thus the electrodynamic force, should be known. This force depends on several factors, including: contact materials, dimensions of relay current paths, relay electromagnetic coil, etc. This paper presents the results of calculations and an experiment on electromagnetic forces, which cover these factors. A static closing force, acting on the contacts, and the fault current were measured. As a result, values of the force and current threshold were obtained, which inform when an electrodynamic bounce may occur. The obtained result may be used in designing contact rivets and relay current paths together with the selection of adequate fault protection devices.

scholarly journals FIRES ON THE HOUSEHOLD LOW-VOLTAGE DISTRIBUTION BOARD CAUSED BY THE ABSENCE OF POLE MOUNTED FUSES AND SURGE ARRESTERS

2013 ◽  
Vol 3 (4) ◽  
Author(s):  
Nedžad Hadžiefendić ◽  
Ivan Zarev ◽  
Nebojša Đenić ◽  
Marko Medić
Keyword(s):  
Low Voltage ◽  
Distribution Network ◽  
Fault Current ◽  
Fire Occurrence ◽  
Voltage Distribution ◽  
Protective Devices ◽  
Surge Arresters ◽  
Fault Currents ◽  
Electrical Distribution ◽  
Electrical Distribution Network

This paper deals with the issue of the fire occurrence which is caused by low-voltage electrical installations (household distribution board) due to the absence of protective devices (fuses and surge arresters) on the pillars of the electrical distribution network. The example of calculation of fault currents is given, for the fault current on the basis of which it is proved the necessity of installing of pole mounted fuse on the latest pillar of low-voltage electrical distribution network. In the paper there are examples of fire expertise for fires caused by non-installation of pole mounted fuses and surge arresters are presented. Key words:atmospheric discharges, over-voltages, fault current, fire, pole mounted fuse, surge arrester

scholarly journals Improving sensitivity of residual current transformers to high frequency earth fault currents

2017 ◽  
Vol 66 (3) ◽  
pp. 485-494 ◽  
Author(s):  
Stanislaw Czapp ◽  
Krzysztof Dobrzynski ◽  
Jacek Klucznik ◽  
Zbigniew Lubosny ◽  
Robert Kowalak
Keyword(s):  
High Frequency ◽  
Low Voltage ◽  
Current Transformer ◽  
Residual Current ◽  
Fault Current ◽  
Earth Fault ◽  
Fault Currents ◽  
Proper Operation ◽  
Current Device ◽  
A Current

Abstract For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.

scholarly journals Monotonic Functions Method and Its Application to Staging of Patients with Prostate Cancer According to Pretreatment Data

2021 ◽  
Vol 11 (9) ◽  
pp. 3836
Author(s):  
Valeri Gitis ◽  
Alexander Derendyaev ◽  
Konstantin Petrov ◽  
Eugene Yurkov ◽  
Sergey Pirogov ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Learning Algorithm ◽  
Binary Classification ◽  
Preoperative Staging ◽  
Threshold Value ◽  
Logical Function ◽  
Adequate Treatment ◽  
Monotonic Functions ◽  
Selection Of

Prostate cancer is the second most frequent malignancy (after lung cancer). Preoperative staging of PCa is the basis for the selection of adequate treatment tactics. In particular, an urgent problem is the classification of indolent and aggressive forms of PCa in patients with the initial stages of the tumor process. To solve this problem, we propose to use a new binary classification machine-learning method. The proposed method of monotonic functions uses a model in which the disease’s form is determined by the severity of the patient’s condition. It is assumed that the patient’s condition is the easier, the less the deviation of the indicators from the normal values inherent in healthy people. This assumption means that the severity (form) of the disease can be represented by monotonic functions from the values of the deviation of the patient’s indicators beyond the normal range. The method is used to solve the problem of classifying patients with indolent and aggressive forms of prostate cancer according to pretreatment data. The learning algorithm is nonparametric. At the same time, it allows an explanation of the classification results in the form of a logical function. To do this, you should indicate to the algorithm either the threshold value of the probability of successful classification of patients with an indolent form of PCa, or the threshold value of the probability of misclassification of patients with an aggressive form of PCa disease. The examples of logical rules given in the article show that they are quite simple and can be easily interpreted in terms of preoperative indicators of the form of the disease.

Multicriteria Decision Approach for Selection of Fault Current Limiters Technology

2019 ◽  
Author(s):  
Handrea Bernando Tambunan ◽  
Putu Agus Aditya Pramana ◽  
Brian Bramantvo Satriaji D A Harsono ◽  
Aristo Adi Kusuma ◽  
Nur Widi Priambodo ◽  
...  
Keyword(s):  
Fault Current ◽  
Multicriteria Decision ◽  
Fault Current Limiters ◽  
Selection Of

Optimisation of very low voltage TVS protection devices

2003 ◽  
Vol 34 (9) ◽  
pp. 809-813 ◽  
Author(s):  
J. Urresti ◽  
S. Hidalgo ◽  
D. Flores ◽  
J. Roig ◽  
J. Rebollo ◽  
...  
Keyword(s):  
Low Voltage ◽  
Protection Devices

A Method for Online Diagnostics of Electromagnetic Relays Against Contact Welding for Safety Critical Applications

2015 ◽  
Vol 5 (12) ◽  
pp. 1734-1739 ◽  
Author(s):  
Srikantam Sravanthi ◽  
Rajamani Dheenadhayalan ◽  
Manickam Pillai Sakthivel ◽  
Kunhiraman Devan ◽  
Kanakkil Madhusoodanan
Keyword(s):  
Safety Critical ◽  
Electromagnetic Relays ◽  
Contact Welding

scholarly journals Sistem Pendukung Keputusan Pemilihan Mobil Bekas Menggunakan Metode Analythical Hierarchy Process

2021 ◽  
Vol 3 (2) ◽  
pp. 380-386
Author(s):  
Gushelmi Gushelmi ◽  
Dodi Guswandi
Keyword(s):  
Selection Process ◽  
Threshold Value ◽  
Internet Technology ◽  
A Value ◽  
Used Cars ◽  
Hierarchy Process ◽  
Selection Of ◽  
Comparison Data

Showroom Ragasa Motor Padang is a showroom that sells various types of used cars. The old system of selecting used cars in The Ragasa Motor Padang Showroom is that customers come directly to the address of this Showroom and the selection process is still done by manual means. With the development of internet technology today is increasing rapidly and in order to be accessible to everyone, the AHP can do a comparison of the criteria in pairs on the selection of used cars and can determine the consistency of the comparison data paired with a threshold value of < 0.1. The purpose of this research is to make it easier for customers to choose used cars quickly and accurately, as well as the application of programs used to make it easier for customers to use them. The result of this study is the SPK System that was built to be able to take the decision of the selection of used cars in the Showroom Ragasa Motor Padang with the selection of the 2nd alternative with a value of 2.55 as the best choice.

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