The effect of brush spring pressure on the wear behaviour of copper–graphite brushes with electrical current

Yasar, I.; Çanakçı, Aykut; Arslan, Fazlı

doi:10.1016/j.triboint.2007.03.005

Cited by 125 publications

(56 citation statements)

References 18 publications

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“…The higher temperature could lead to wear acceleration, resulting in damage of the delivery end of the brush. So, this phenomenon elucidates the accelerated brush surface damage in electrical machines [18,36,46,74]. Now we can evaluate a relative error of the pressure change in the contact area being the function of time: It is interesting to note that the largest error occurs in the area formed under the leading edge of the brush and the commutator that is where a highest sliding velocity at the contact area, whereas the smallest error occurs in the area formed under the trailing edge of the brush where the sliding velocity decreases.…”

Section: Discussion and Analysis Resultsmentioning

confidence: 84%

“…This means that geometry, physical properties, and wear behaviour of this dynamic system are the probability values. The pressure and temperature play an important role among these factors [18][19][20][21]. It arises from the media properties which depend on the velocity of the particle in the surrounding (gas or lubricant) and therefore the dissipation of heat away from the area [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

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Effect of pressure changes in sliding contact

Deeva¹,

Slobodyan²

2018

IJET

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The sliding contact when the air together with wear particles flow in contact area between commutator and brush is considered. The dynamical interaction between two surfaces is probabilistic. The behaviour of space-time-varying process is described by the differential equations, which are generally very difficult to solve. The simple numerical solution applying the method of Galerkin approximation to estimate the change in the pressure field in thin contact layer is obtained. It was found that under the leading edge of the brush the pressure change doesn't exceed 0.07 of the maximum value. The numerical simulations of the absolute error are presented for the 0.1, 0.2, 0.5, and 1 of the relative length. The relative error of pressure changes for small contact area is smaller (1 -0.8e 0.1τ). It is concluded that the approximate solution tends to the exact one. Moreover, it is shown that as the sliding velocity decreases, the relative error of the pressure change tends to the zero.

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Section: Discussion and Analysis Resultsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Effect of pressure changes in sliding contact

Deeva¹,

Slobodyan²

2018

IJET

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“…Yasar et al 18 researched a different material pair (copper-graphite brush sliding against a steel slip-ring) and varied the brush-spring pressure; however, for the brush-spring force, they found that the friction initially decreases and finally increases. Yasar et al's report is relevant to this research as it shows that optimal operating conditions can significantly reduce the wear rate (and the contact resistance).…”

Section: Discussionmentioning

confidence: 99%

Electrical contact resistance and wear of a dynamically excited metal–graphite brush

Turel

Slavič

Boltežar

2017

Advances in Mechanical Engineering

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The wear and contact resistance of sliding contacts are typically researched with a pin-on-disk experiment that prevents dynamic excitation. However, in electrical machines, the brush clearance enables dynamic excitation, resulting in flexible body dynamics. To research the wear and contact resistance during dynamical excitation, an in-situ experimental approach is introduced here, with the influences of rotational speed, electrical current, and temperature being assessed. This research shows that a small wear rate and contact resistance are possible at 10,000 and 5000 RPM if the electrical current is higher than 3 A. It was also found that the contact resistance decreased with an increased ambient temperature, electrical current, and rotating speed, whereas the wear rate increased with the rotating speed at low current density and low ambient temperature.

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“…Therefore, a lot of attention has been given to the prediction of wear in electrical contacts [1] to [3]. The influence on the wear rate has been investigated for the sliding speed [4] to [6], electrical current [7] to [9], ambient conditions [10] and [11], contact pressure [5], [8] and [12] and material properties [13] to [15] of a brush. In addition to the mentioned parameters, attention has also been given to the dynamics of the brush through the coefficient of friction [16], brush stability [17] and vibrations [18] to [21].…”

Section: Introductionmentioning

confidence: 99%

Wear Rate vs Dynamic and Material Properties at Elevated Temperatures for a Copper-Graphite Brush

2018

SV-JME

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A copper-graphite brush is used as a sliding part in the electrical contacts of electrical machines and usually operates at elevated temperatures. This experimental research relates the dynamic properties of the copper-graphite brush to its INTRODUCTIONSliding electrical contacts are necessary whenever an electrical current needs to be transferred between a stationary and a rotating part, like in alternators or DC motors. A brush and a slip-ring or commutator, which form the contact, are the primary components that affect the lifetime of electrical machines. Therefore, a lot of attention has been given to the prediction of wear in electrical contacts [1] The wear rate and dynamics of a copper-graphite brush are highly dependent on the properties of the brush material [1]. The material properties can be researched by differential thermal analysis (DTA) or by thermogravimetric (TG) analyses, e.g., Kuz'mina et al. [22]. They observed that an increase in the copper content in the composite leads to a change in the shape of the TG curves, while the binder properties, an ordinary compound of the brush composite, can be tested with differential scanning calorimetry (DSC) [23]. In addition to the DSC analyses, the material properties were also studied using hardness tests [24].The effect of temperature on the dynamic properties of the brush is not commonly referred to as an influencing wear parameter, and only a few studies have paid attention to these properties separately [17], [20], [22] and [25].The aim of this study was to analyse the effect of temperature on the dynamic properties of the copper-graphite brush and to compare it to the wear rate.The dynamic properties were investigated through the natural frequencies, the hysteretic damping ratio and evaluated through the material's properties, i.e., hardness tests and DSC, while the wear rate was measured previously, see, e.g., [26].This research is organised as follows: in Section 1 the experimental methodology is introduced, in Section 2 the experimental results with a discussion are presented, and in Section 3 the conclusions are given. EXPERIMENTAL RESEARCHIn the experimental research section the methods and conditions for the dynamic response analyses, DSC, hardness and wear rate are presented. The dynamic properties were researched using dynamic response analyses, compared to the wear rate of the copper-graphite brush. For an additional insight into the effect of temperature on the brush material's

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The effect of brush spring pressure on the wear behaviour of copper–graphite brushes with electrical current

Cited by 125 publications

References 18 publications

Effect of pressure changes in sliding contact

Effect of pressure changes in sliding contact

Electrical contact resistance and wear of a dynamically excited metal–graphite brush

Wear Rate vs Dynamic and Material Properties at Elevated Temperatures for a Copper-Graphite Brush

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