Determining the fault current time of 1, 3, or 5 seconds for grounding cable sizing involves considering several factors, including the RMS value of the fault current and the heat capacity of the conductor. The required cross-section of the cable conductor can be calculated using the formula S = C⋅Ifault⋅√t, where C is a constant based on the cable's material and design. The temperature increase allowed during this time is typically between 100-150 °C. Additionally, understanding the reactive energy being dumped during a short circuit event and the fusion current of the conductor is crucial for effective sizing. Accurate calculations ensure safety and reliability in electrical systems.
