The relationships between surface roughness, contact pressure and contact resistance are studied in this work published three years ago.
It is imporant to distinguish between the different conduction mechanisms acting at contacts at different scales, in order to better understand how surface structure and surface chemistry can alter the behaviour of electrical contacts
Understanding electrical contact resistance
Electrical contact resistance at interfaces between pairs of rough surfaces is of great importance in the performance of diverse systems, particularly in miniaturised electromechanical systems containing switches.
In this study, the role of pressure and surface structure is explored with a view towards gaining a beter understanding of electrical contact resistance.
Electrical Contact Resistance of Fractal Rough Surfaces
The presence of roughness at electrical contacts tends to involve contacting asperities across multiple scales. Depending on the nature of the contact between asperities on opposing surfaces, different conduction mechanisms take place. This is shown in the figure here.
I am electrical engineer at Indonesian Railways. I need to calculate maximum current and time for pantograph and trolley wire contact when it is not moved, but i have difficulties when determine contact resistance between them. please inform me any hint or else. thank you.
Surfaces are rough on the microscopic scale, so contact is restricted to a few `actual contact areas'. If a current flows between two contacting bodies, it has to pass through these areas, causing an electrical contact resistance. The problem can be seen as analogous to a large number of people trying to get out of a hall through a small number of doors.
Classical treatments of the problem are mostly based on the approximation of the surfaces as a set of `asperities' of idealized shape. The real surfaces are represented as a statistical distribution of such asperities with height above some datum surface. However, modern measurement techniques have shown surfaces have multiscale, quasi-fractal characteristics over a wide range of length scales. This makes it difficult to decide on what scale to define the asperities.
