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 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.

Generation of testing script based on XML for safety-critical systems

2011 ◽  
Vol 31 (1) ◽  
pp. 281-285
Author(s):  
Huan HE ◽  
Zhong-wei XU ◽  
Gang YU ◽  
Shi-yu YANG
Keyword(s):  
Critical Systems ◽  
Safety Critical ◽  
Safety Critical Systems

Investigation of pre-sprayed powders for electric contact welding

2020 ◽  
pp. 143-149
Author(s):  
Dinar R. Masalimov ◽  
Roman R. Galiullin ◽  
Rinat N. Sayfullin ◽  
Azamat F. Fayurshin ◽  
Linar F. Islamov
Keyword(s):  
Adhesion Strength ◽  
Electrical Contact ◽  
Research Purpose ◽  
Flame Spraying ◽  
Powder Materials ◽  
Electric Contact ◽  
Metal Powders ◽  
Unstable Flow ◽  
Gas Flame ◽  
Contact Welding

There are a number of difficulties in the electrical contact welding of powder materials: shedding of powder from the surface of a cylindrical part, impossibility of hardening the layer during welding due to flushing of the powders with coolant and unstable flow of powder into the welding zone. One solution is pre-spraying the powder in some way. (Research purpose). The research purpose is investigating the possibility of electric contact welding of metal powders preliminarily sprayed by a gas-flame method, namely, adhesion strength and losses during preliminary gas-flame spraying of powders. (Materials and methods) Powders of grades PG-NA-01, PrKhIIG4SR, PRZh3.200.28 were sprayed onto flat samples of St3 steel, polished to a roughness of Ra 1.25. The strength of powder adhesion to the base was studied by the cut method. (Results and discussion) The percentage loss of the powder as a whole is 3-23 percent for all the distances studied. The greatest powder losses appear at a distance of more than 180 millimeter from the tip of the burner for powders of grades PG-NA-01 and PrKhIIG4SR. The smallest powder losses were observed for PrZh3.200.28 powder, which totaled 3-7 percent. The maximum adhesion strength of the sprayed powders to the surface was 22.1 megapascals' when spraying the PG-NA-01 powder. The adhesion strength of powders of the grades PrKhIIG4SR and PrZh3.200.28 is small and amounts to 0.2-3 megapascals'. (Conclusions) The use of preliminary flame spraying of powders for their further electric contact welding is possible using PG-NA-01 grade powder, while the best adhesion to the base (that is more than 20 megapascals') is achieved with a spraying distance of 120-140 millimeter. The smallest powder losses during flame spraying are achieved at a spraying distance of 100-160 centimeters', at which the powder loss for the studied grades was 4-12 percent.

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