The determination of fault current time for grounding cable sizing is critical and can be set at 1, 3, or 5 seconds based on specific system requirements. The formula for calculating the required cross-section of the cable conductor is S = C⋅Ifault⋅√t, where C is a constant based on the cable's material and design, Ifault is the RMS value of the fault current in kA, and t is the fault time in seconds. The allowable temperature increase during this period typically ranges from 100 to 150 °C. Understanding the fusion current and heat capacity of the conductor is essential for ensuring safety and performance during short circuit events.
PREREQUISITESElectrical engineers, system designers, and safety professionals involved in grounding system design and short circuit analysis will benefit from this discussion.
Required cross section of cable conductor in mm2 is :Khaled Abuzaid said:Any idea how can we decide on the fault current time 1, 3 or 5 sec. for grounding cable sizing? Also, what is the related temperature to the selected timing?