Evaluation of Basic Electrical Parameters of Silver-Based Contact Materials of Different Chemical Composition and Manufacturing Technology

Walczuk, E.; Borkowski, P.; Księżarek, S.; Missol, W.; Rdzawski, Z.; Durst, Karsten

doi:10.1109/holm.2010.5619550

Cited by 5 publications

(8 citation statements)

References 1 publication

(1 reference statement)

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“…The operation of making significant currents may lead to contact bounces. Together with the increase of values for the contacting current’s amperage, there is the increase in the mass loss of the contact rivet [11,21,22,23].…”

Section: State Of the Artmentioning

confidence: 99%

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Change in Electric Contact Resistance of Low-Voltage Relays Affected by Fault Current

2019

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Contact resistance is an important maintenance parameter for electromagnetic switches, including low-voltage relays. The flow of significant current through electric contacts may influence the contact surface and thus the value of the electric contact resistance (ECR). The change in ECR is influenced not only by the value of current but also by the current phase. Therefore, the impact of the switching short-circuit current’s phase on the ECR was analyzed in this paper. Significant changes in the resistance after each switching cycle were observed. The ECR decreased significantly after each make operation, and a correlation with current amplitude, total let-through energy, and short-circuit time was not observed.

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Section: State Of the Artmentioning

confidence: 99%

“…Presently, the most common contact materials for low-voltage relays of alternating currents of average power are sinters of silver with nickel (AgNi), cadmium oxide (AgCdO), and tin oxide (AgSnO 2 ). Materials that are made of silver-metal or silver-metal oxide typically present higher resistance to welding [11].…”

Section: Introductionmentioning

confidence: 99%

Change in Electric Contact Resistance of Low-Voltage Relays Affected by Fault Current

2019

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“…With the increase in the value of the switching current intensity increases the loss of mass of the contact point [2,18,21]. In addition, the arc can lead to a strong local heating of the arc spot, even above the melting point of the contact material [12].…”

Section: Fig 2 the Oscillogram Of Current Intensity In The Test Cirmentioning

confidence: 99%

“…Materials made as silver-metal or silver-metal oxide are generally having a high resistance to welding [21]. The frequency and strength of welding during switching increases proportionately to the value of switching current arc, while the arc burning time has no such influence [17].…”

Section: Introductionmentioning

confidence: 99%

Low voltage relay contact resistance change influence by short-circuit current

Książkiewicz¹,

Janiszewski²

2015

EiN

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IntroductionElectromagnetic relays are commonly used to connect circuitry with moderate values of the switching current (i. e. the medium current circuits) at a voltage not exceeding 1000 V. They are used inter alia as actuators in the building automation systems (eg. KNX, LCN, LonWorks) or in drivers and the programmable relays (Easy, NEED). They differ among themselves with a structure, purpose, and technical parameters. In regard to the contacts of connectors made of different materials, in literature, there are often presented results of research carried out as well in normal operation as in terms of specific exposures. These studies, however, are often focused on the low voltage (<50 V) direct current circuits [8]. Similar research were performed by Morin [16], Neuhaus [17] or Doublet [6], who independently conducted similar work for contacting materials for low voltage direct current circuits. Research related to processes of switching in circuits of medium voltage alternating current are focused on current ranges from a few to several kA [1,9]. A noticeable is the lack of research in the field of low-and medium current AC switches at currents close to normal and short-circuit working conditions which may occur in low voltage electrical installations, that usually do not exceed 1 kA. Within the scope of modeling simulation studies are being conducted on the heating rail and contact connections with complex shapes, configurations and utilizing a variety of conductive materials [10].Relays for connecting the receiving circuits are exposed to unfavorable processes. These phenomena may include closing overload and short-circuit currents, which may lead to shortening the life ofrelays or, in extreme cases, their total damage. The article describes the impact of switching short-circuit on the change of the contact resistance. Relays with three different contacting materials have been investigated.Contact resistance of the connector is the important performance parameter. It is important that during the utilisation of the relay this resistance reaches values as small as possible and simultaneously do not differed significantly in time. Among other things, associated with its heating the safe working load of the relay depends on its value [15]. The contact resistance value is dependent on [7,14]:shape resistance -The resultant value of contact resistance (transition) is equal to:The tarnish resistance R n is difficult to determine analytically, since it depends on multiple, sometimes random, factors including: temperature, humidity, contact material. The shape resistance R k mainly depends on the resistivity and hardness of the contact material. To its description the single-point model with elliptical, equipotential current flowlines is often used [5,7]. The actual contact area is much smaller than the apparent (nominal) surface of the contact point. This model can be considered correct, at low contact pressure forces used in relays.The value of the contact resistance is affected by the material used for the con...

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“…Contact material has a major influence on the performance of relays, contactors and other switching devices affecting maximum inrush current, maximum switching current, contact resistance together with contact reliability and electrical life. A majority of contact applications in the electrical industry utilize silver-type composite contact materials [6][7][8][9][10][11]. These include powder metal combinations which offer combinations of metals ordinarily cannot be achieved by alloying (ASM [12]).…”

Section: Introductionmentioning

confidence: 99%

The effect of the amount of process control agent on the properties of Cu25W composite powder

Biyik

Aydın

2014

WIT Transactions on the Built Environment

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This study is based upon the optimization of production parameters of Cu25W electrical contact material. Commercial elemental copper (Cu) and tungsten (W) powders were synthesized to produce Cu25W composite powder by mechanical alloying technique at various amounts of stearic acid via using a planetary type ball mill. The effect of amount of stearic acid on production of Cu25W composite powder was evaluated. In order to achieve true alloying among powder particles, it is necessary to establish a balance between cold welding and fracturing. Hence, different types of process control agents (PCA) were used to reduce excessive cold welding. Here, the effect of various amounts of stearic acid, namely 0, 0.5, 1, 2 and 3 wt.% on morphology and some properties of Cu25W composite powder were studied. The microstructural evolution of the milled powders was characterized by using scanning electron microscopy. The test results showed that the morphology and particle size distribution of the milled powders were changed considerably depending upon the variable amount of PCA. In addition, holding the same milling duration, different microhardness values were obtained for various amounts of PCA.

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Evaluation of Basic Electrical Parameters of Silver-Based Contact Materials of Different Chemical Composition and Manufacturing Technology

Cited by 5 publications

References 1 publication

Change in Electric Contact Resistance of Low-Voltage Relays Affected by Fault Current

Change in Electric Contact Resistance of Low-Voltage Relays Affected by Fault Current

Low voltage relay contact resistance change influence by short-circuit current

The effect of the amount of process control agent on the properties of Cu25W composite powder

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