Path Rating Catalog 2013 - Western Electricity Coordinating Council

38. TOT 4B
Revised January 2012
Accepted Rating
Existing Rating
Other
Location:
Definition:
Northwest Wyoming
Sum of the flows on the following transmission lines:
Line
Metered End
CarrDraw-Buffalo 230 kV
CarrDraw
Sheridan-Tongue River 230 kV Sheridan
Spence-Thermopolis 230 kV Spence
Alcova-Raderville 115 kV
Alcova
Casper-Midwest 230 kV
Casper
Riverton-Thermopolis 230 kV Riverton
Riverton-230/115 kV transformers Riverton 230 kV
Subtract PreCorp load at Sheridan
Transfer Limit: Southeast to Northwest: 680 MW (Non-simultaneous)
Northwest to Southeast: Not defined
Critical
Disturbance
that limits the
transfer
capability:
When:
System
Conditions:
Study Criteria:
Remedial
Actions
Required:
Depending on flows on the adjacent TOT 4A path, the real-time rating can
range between a minimum of 0 MW and a maximum of 680 MW (Reference
attachment). Typically, the real-time rating centers around 475 MW.
The critical disturbances and limiting elements vary with the various points
on the nomogram. Reference attachment for further information.
Phase 1/2 Rating Study Underway
This rating is independent of transfer levels between major areas of WECC.
Historically, the flows have all been southeast to northwest across the path.
(Summary)
System intact:
• Per unit voltages between 0.95 p.u. and 1.05 p.u.
• All lines and transformers loaded to less than continuous rating.
Single contingency outage conditions:
• Per unit voltages between 0.90 p.u. and 1.10 p.u.
• All facilities loaded to less than 100% of emergency ratings.
Remedial actions are required to achieve the rated transfer capability.
Following an outage, all overloaded lines and transformers must have their
loading reduced to continuous ratings within 15 minutes. This is
accomplished by reducing schedules or lowering local generation.
PART VI Item 1-107