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Project 2009-06
Facility Ratings
Related Files
Purpose/Industry Need:
The expansion
of this project is necessary to address a directive from Order 693 that
was not addressed in FAC-008-2 – Facility Ratings.
There were three directives in Order 693 relative to FAC-008-1 –
Facility Ratings:
(1) document underlying assumptions and methods used to determine normal
and emergency facility ratings;
(2) develop facility ratings consistent with industry standards
developed through an open process such as IEEE or CIGRE and
(3) identify the limiting component(s) and define the increase in rating
based on the next limiting component(s) for all critical facilities.
The version of FAC-008-2
that was approved in 2010 only addressed the first two of the three
directives. FERC’s September
16, 2010 Order
Denying Rehearing, Denying Clarification, Denying Reconsideration, and
Denying Request for a Stay on its March 18 Order included the following
clarification regarding the third directive:
“In order to determine facility ratings, entities must identify the most
limiting component that comprises the facility, based on a validated
methodology that considers the specific characteristics and ratings of
all of the components to determine their limits for a range of ambient
conditions, including if and for what duration these limits can be
exceeded. This is, in part,
because the limiting element upon which a facility rating is based can
change under different operating conditions. For example, an underground
high voltage cable may be the limiting element for continuous ratings,
but a disconnect switch may be the limiting element for a four-hour
emergency rating. With heavy power flows from generators through
critical facilities to load, contingency conditions could reveal a
thermal overload above the normal rating of the first limiting component
of one of these facilities. However, that component also likely has a
documented short time rating that could sustain the overload. If the
second-most limiting component does not afford much increase in rating
above the first, and its overload can result in the unintended removal
of the facility from service (i.e., a relay or other protection system
component that trips a facility out of service due to the overload), the
prior identification of this second limiting component could alter the
mitigation plans and avoid relay operations that trip facilities
out-of-service, and thus potentially prevent a cascading event.”
With this additional clarity, the drafting team has developed a
new requirement to address the reliability intent of the third
directive. NERC received a final order on March 17, 2011 granting
the ERO 90 days to file a version of FAC-008 that addresses all three of
the directives from Order 693, making the filing due on June 15, 2011.
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