Temperature Coefficient of Resistance

Copper's resistance varies with temperature. According to IEC 60028, the temperature coefficient of resistance (α) at 20°C is:

α = 0.00393 per °C
This coefficient is used to calculate the resistance of copper at different temperatures using the formula:

R_T = R_20 ⋅ [1 + α ⋅ (T - 20)]
Where:

• R_T: Resistance at temperature T (in °C),
• R_20: Resistance at 20°C,
• α: Temperature coefficient of resistance (0.00393 per °C).

Example Calculation:

Given:

• R_20 = 0.1 Ω
• T = 50°C

The resistance at 50°C (R_T) is calculated as:

R_T = 0.1 ⋅ [1 + 0.00393 ⋅ (50 - 20)]
R_T = 0.1 ⋅ [1 + 0.00393 ⋅ 30]
R_T = 0.1 ⋅ [1 + 0.1179]
R_T = 0.1 ⋅ 1.1179
R_T = 0.11179 Ω
Conclusion: The resistance of the copper conductor at 50°C is approximately 0.1118 Ω.