Path Rating Catalog 2013 - Western Electricity Coordinating Council

Revised January 2013
28. Intermountain - Mona 345 kV
Accepted Rating
Existing Rating
Other
Location:
Definition:
Transfer Limit:
Critical
Disturbance
that limits
transfer
capability:
When:
System
Conditions:
Study Criteria:
Remedial
Actions
Required:
Formal
Operating
Procedure:
Allocation:
Interaction
w/Other
Transfer Paths:
Transmission line from Intermountain Power Facility (IPF) at Delta, Utah to
Mona station in central Utah
Two 50-mile 345 kV transmission lines from the 345 kV IPF station to the
345 kV Mona station. The IPF 345 kV station is in the Los Angeles
Department of Water and Power (LDWP) control area, while the Mona
345 kV station is in the PacifiCorp control area.
East to West: 1200 MW
West to East: 1400 MW
N-1 load flow studies
These ratings were established in 1987, when the IPF was first put into
service. These ratings have been documented in the WECC Operations
Committee’s Non-Simultaneous Transfer Capability Diagram as well as in
the NERC Form OE-411, Item 5A reportings.
East to West: Sum of a) 200 MW: Intermountain-Gonder line nonsimultaneous
capability, and b) 1000 MW: IPPDC capability with the two
IPF units at minimum generation output (1920 - (2*460 MW)). This is N-1
rating since each line’s thermal capability is above 1400 MW.
West to East: Based on N-1 load flow with two IPF generating units on line.
The thermal capability of the IPF-Mona 345 kV lines is above 1400 MW.
WECC Reliability Criteria for System Design. (The applicable WECC
reliability criteria at that time.)
A back-up protection to the IPF unit tripping RAS (the IPP Contingency
Arming System) trips the IPF-Mona 345 kV line for failure of the IPF RAS.
The relay protection, which is based on power surge measurement on the
lines, trips the lines if the power surge exceeds a pre-selected power level.
The power surge on these lines is expected to exceed the relay tripping level
only when there are IPF bipole outages or two unit IPF tripping, and failure of
the IPF RAS.
There are automatic and operating procedures to fast-reclose the Mona lines
whenever the lines are tripped due to the power-surge relay protection or
other causes.
The following utilities have entitlements on these lines:
LDWP, Anaheim, Riverside, Pasadena, Burbank, Glendale, and PacifiCorp.
PART VI Item 1-79