FLEXIBLE SUBSTATION BUSES. Flexible substation bus ratings shall be assigned in accordance with IEEE Standard 738-2006. IEEE Standard 738-2006, and the included rating program RATEIEEE, address both steady-state and transient ratings. Since the thermal time constant of a flexible bus conductor is generally greater than 15 minutes, the steady-state calculation is to be applied in determining Normal and Long-Time Emergency ratings. The transient calculation is applied in determining Short-Time Emergency ratings and Drastic Action Limits. In all cases, adequate clearances must be maintained with flexible bus conductor loadings at the rated values.
