This guide explains the fundamentals of calculating voltage drop and heat generation in electrical cables, particularly for high-current applications such as welding cables. The following formulas and considerations are essential for selecting the appropriate cable size and managing heat in electrical systems.
Calculating Voltage Drop
Voltage drop occurs when electrical current flows through a wire, causing a reduction in voltage due to the wire's inherent resistance. The formula for voltage drop is:
Vdrop = I × R × L
Where:
- I = Current (Amps)
- R = Wire resistance (Ohms per foot)
- L = Round-trip length of the wire (feet)
For further details on voltage drop, visit McClelland Online.
Calculating Heat Generation (Power Loss)
As current flows through a cable, resistance causes power loss in the form of heat. The formula is:
P = I² × R
This gives the power loss in Watts per foot. To learn more about power loss in cables, check out The Engineering Toolbox.
Estimating Temperature Rise
The heat generated by power loss increases the cable temperature. A rough estimate for temperature rise is:
ΔT = P × Rthermal
Here, Rthermal represents the thermal resistance (in °C/W or °F/W). The actual temperature rise will depend on factors such as cable bundling, airflow, and ambient temperature.
Practical Considerations
- If the voltage drop is excessive, consider using a larger wire to reduce resistance.
- If too much heat is generated, improve cooling or lower the current.
- Always consult manufacturer ampacity charts to ensure safe operating limits.
For a quick and interactive calculation of these values, try the Cable Loss Tool.
Special thanks to Julian Smith for his contributions and long brotherhood <3