The following calculator computes the expected time for a cable, conductor, or bus bar to rise in temperature under short circuit or short-time overcurrent conditions. The calculator uses empirical formulas that consider all heat generated by I2R losses in the conductor during an overcurrent condition to be absorbed by the conductor and that no heat is transmitted from the conductor to its surroundings.
Calculator-1
Known variables: Conductor cross-sectional area (Circular Mils), Conductor Material, Short Circuit/Overload Current (RMS Amperes), Operating Temperature, Maximum Temperature
Formulas and Variables
Copper Conductors
Aluminum Conductors
Where:
T = Time Duration of Short Circuit/ Overcurrent Condition (seconds) |
Θ1 = Operating Temperature (degrees Celsius) |
Θ2 = Maximum Temperature (degrees Celsius) |
A = Cross-Sectional Area of Conductor |
I = Short Circuit / Overload Current (RMS Amperes) |
Conductor / Cable / Bus Bar Data
Tables below provide circular mil and area information for various size conductors and bus bar for reference purposes.