This paper presents the comparison of station blackout (SBO) frequency computed with approximate time averaged expressions for diesel generator unavailability and time dependent cutset evaluation method. It is found that the frequency of SBO is under predicted by a factor of 2 by approximate time averaged expressions for SBO durations of 8 h and 16 h. The time dependent cutset evaluation method is applied for offsite power feeder outage management by treating the change in SBO frequency when one of the feeders is taken out for maintenance for n days, as the risk measure.