# Derating of Electrical Contacts with Varying Surface Roughness
## 3 Results
The data illustrate the influence of surface roughness on electrical conductivity under varying current levels. The curve labeled \"Base plot\" (orange line) and \"Corrected plot\" (dashed line) show the gradual decrease in current values with increasing ambient temperature, indicating the limitation of current conduction capability at higher temperatures. The maximum temperature (indicated by the dashed red line) is 100 \({}^{\circ}\)C. Additionally, the \"Sample temperature plot\" (blue line) shows a linear increase in the sample temperature depending on the ambient temperature. The marked points on the figure represent specific current values and their corresponding temperatures. It helps to understand how the increase in temperature affects the ability to conduct current through a contact with a specific roughness. The table presents values related to the derating curve from the previous graph. It contains data on current, sample temperatures, average temperatures, and temperature increases under various conditions. The first row lists current values in amperes, from 1 A to 20 A, and the second row shows the corrected current values, which gradually increase from 0.8 A to 16 A. The following rows present the temperatures measured for three samples in degrees Celsius, which increase as the current increases, indicating the heating effect. The \"Average\" row contains the average temperature values for the three samples in each tested situation. There is a systematic increase in the average temperature from 23.66 \({}^{\circ}\)C for the lowest current to 66.66 \({}^{\circ}\)C for the highest. The \"Temp. increase\" row shows the difference between the initial temperature and the final temperature, illustrating the temperature rise from 0.09 \({}^{\circ}\)C at 1 A to 42.08 \({}^{\circ}\)C at 20 A. The last row, \"Max. amb. Temp.\", shows the maximum possible ambient temperature for the given current, decreasing from 99.91 \({}^{\circ}\)C at 1 A to 57.92 \({}^{\circ}\)C at 20 A. The Table 5 provides a detailed overview of the impact of current intensity on sample temperatures and the temperature limitations of the contact with roughness R\({}_{2}\)10. The conclusions for contacts with a roughness of R\({}_{2}\)10 derived from the presented data highlight the key properties of this type of surface in the context of current conduction and temperature management. The roughness of R\({}_{2}\)10 can affect the thermal characteristics of the contact, as seen in the relationship between current and temperature. As the current increases, a systematic rise in the temperature of the samples is observed, which is the result of heat losses due to current conduction through a contact with a specific roughness. The corrected current values indicate a limitation due to temperature, which can be crucial for protecting the material from overheating. The increase in the sample temperature, shown in the table as the difference between the initial and final temperature, grows nonlinearly, meaning that at higher current values, the heating effect is more intense. The maximum  
Figure 6: Derating characteristics of samples with surface roughness R\({}_{x}\) 10. The plot shows the permissible current as a function of ambient temperature, illustrating thermal limitations under increasing load conditions.