Equipment Evaluation

The Equipment Evaluation Study compares the protective device ratings with the short-circuit calculations for various operating conditions. The evaluation status for each component is set to “marginal” or “fail” when the specified criteria limits are not met. The equipment listed as “fail” is considered over-dutied since the available short-circuit current exceeds the equipment rating. These are reported in table format to identify for corrective action. The interrupting rating of protective devices must be greater than the calculated fault current available at the equipment location in order to pass the equipment evaluation process. The Equipment Evaluation Study assures safety of personnel and protects equipment per ANSI Standards.

The ANSI, UL and NEMA Standards outline the preferred method used to calculate the fault duty for electrical equipment. The equipment must withstand the thermal and mechanical stresses produced by the short-circuit current. The calculated fault duty is compared to the equipment ratings to verify that that the equipment will safely withstand the maximum available fault current. The calculated fault duty is required in order to adequately determine the short circuit withstand and interrupting ratings for the electrical apparatus. The results from the short-circuit study are used in the calculation for the equipment evaluation and the arc flash study. (Note: A “Dangerous Hazard” Label, instead of the calculated arc flash label is provided for over-dutied equipment)

Custom table can be sorted by bus for field verification. In addition to the normal power mode, multiple operating scenarios can be created to determine the calculated fault duties for various system configurations. The calculated fault values for the different cases are analyzed and compared to determine the worst case results that are in turn compared to the equipment ratings and reported.