"Mission Critical  Mission critical describes a system, component, or application whose misoperation could directly contribute toward the loss of a 50 MW or larger generating resource, the loss of a transmission facility, or interruption of system load."

(From the "Readiness Assessment" spreadsheets, emphasis added.)

Why is that "50 MW or larger" in there?

(See NERC August report online.)

-- Anonymous, August 08, 1999

Answers

Hi Lane. My understanding on this is that for generating sources, they only wanted an assessment of medium to large units. Because there are so many small generators out there (tens of thousands), and the loss of small units does not generally affect grid stability or service to customers, the primary focus has been on the bigger units.

Perhaps you are assuming that the 50 MW also applied to customer load? It doesn't; any device that would shut off power to any customer, large or small, qualifies as mission critical. Most distribution feeders have less than 10MW load on each. I hope this helps.

-- Anonymous, August 08, 1999

I don't know why 50 MW is in there and I don't like it either. That doesn't contribute much so I will point out that further criteria for mission critical are mentioned in the paragraph.

-- Anonymous, August 08, 1999

Thanks, Dan (or whatever your name really is).

-- Anonymous, August 08, 1999