Path Rating Catalog 2013 - Western Electricity Coordinating Council

Revised December 2010
22. Southwest of Four Corners
Location:
Northeastern Arizona
Accepted Rating
Existing Rating
Other
Definition: Sum of the flows on the following transmission lines (see Fig. 1):
Line
Metered End
Four Corners-Moenkopi 500 kV Four Corners 500 kV
Four Corners-Cholla #1 345 kV Four Corners 345 kV
Four Corners-Cholla #2 345 kV Four Corners 345 kV
Transfer Limit: East-West: 2325 MW
West-East: Undefined
The 2325 MW nominal operating limit is limited by the thermal rating of the
Four Corners-Cholla 345 kV lines and voltage deviation at Pinnacle Peak
following the critical disturbance. The actual rating is defined by the vertical
and horizontal elements of the attached nomogram (Fig 2).
Critical
Disturbance
that limits the
transfer
capability:
When:
The critical disturbance is dependent on the location along the nomogram.
Two critical contingencies for defining the nomorgram are loss of the Four
Corners-Moenkopi line and loss of the Four Corners-Cholla #2 345 kV line.
The TTC rating was established in the mid 1980’s by the Four Corners
Technical Studies Task Force and verified by 2010 System Operating Limit
(SOL) studies. The task force is comprised of members from the following
companies:
• Arizona Public Service Company
• El Paso Electric Company
• Public Service Company of New Mexico
• Salt River Project
• Southern California Edison Company
• Tucson Electric Power Company
System
Conditions:
Study Criteria:
Remedial
Actions
Required:
Formal
Operating
Procedure:
Flows on this transfer path have historically been east to west due to the large
amount of generation located in northwestern New Mexico. This generation
is partly owned by entities west of the Arizona - New Mexico border.
The 2325 MW nominal limit was determined due to voltage deviation and
thermal constraints.
Same as WECC Reliability Criteria and NERC Planning Standards for
Transmission System Planning.
None
None
PART VI Item 1-60