Why Prefer Source Impedance Data over Infinite Bus Calculation for Arc Flash Studies

Why Prefer Source Impedance Data over Infinite Bus Calculation for Arc Flash Studies

A utility company may be reluctant to provide the source impedance (fault data) on the primary side of the utility transformer for an Arc Flash Study for several reasons. Understandably requests for utility data might be delayed due to a reduction in staff and increased workloads. However from a liability standpoint some may assume that it is better to provide the utility customer with the maximum fault current believing that this will result in the highest arc flash PPE category, and that their risk of liability is greater if an arc flash injury occurs and the source input data is less than the maximum fault current value. Is this line of reason in the best interest of the utility company or its customer? Who is responsible to evaluate the worst cast incident energy results and what input data should be used?

Read More