General Notice to MISO OASIS Users
NSP/NSPW 345 kV Insulator Replacement Project
February 20, 2004
Xcel Energy is planning to replace polymer insulators on approximately 120 transmission
structures along three 345 kV lines on the NSP and NSP-Wisconsin transmission systems
starting on March 15, 2004 and ending April 10, 2004. The insulator replacement project
will require scheduled outages of the King/Eau Claire/Rocky Run 345 kV line and the
Prairie Island/Pleasant Valley 345 kV line. The tentative outage schedule is shown below.
Background
In the past four years we have experienced insulator failures that caused four trips of the 345
kV line between the A.S. King generating plant and Rocky Run, including two failures within
the past month. To minimize the potential for a future insulator failure to affect the
availability or reliability of the 345 kV lines during the upcoming 2004 Summer Season, we’re
replacing insulators on the King/Eau Claire/Rocky Run and Prairie Island to Pleasant Valley
345 kV transmission lines.
The affected lines are:
 An 84-mile section from the Allen S. King plant in Oak Park Heights, Minnesota to
Eau Claire, Wisconsin.
 A 100-mile section from Eau Claire to Rocky Run substation located south and east
of Stevens Point, Wisconsin
 A 76-mile section from the Prairie Island plant near Red Wing, Minnesota, south to
the Iowa border
Outage Schedule
The insulator replacement project is being coordinated through the Midwest ISO outage
scheduler so the transmission line outages required to perform the insulator replacement are
scheduled consistent with regional reliability requirements.
The specific transmission line section outages for the insulator replacement project are
tentative and are being confirmed with MISO and neighboring utilities to avoid conflicts
with planned or ongoing outages of lower voltage (below 100 kV) systems, particularly on
the ATCo system. The following are the line sections with their tentative outage dates.
Line number 3102 Arpin – Rocky Run
Line number 3102 Eau Claire – Arpin
Line number 3101 A.S. King – Eau Claire
Line number 0979 Prairie Island – Byron
Line number 0979 Byron – Pleasant Valley
3/15/04 to 3/19/04
3/19/04 to 3/29/04
3/28/04 to 4/1/04
4/2/04 to 4/6/04
4/6/04 to 4/10/04
When finalized, the specific outages and dates will be reflected in the MISO outage
scheduler. OASIS users that may be affected by the outage of a specific line should
periodically consult the MISO outage scheduler system for the most up to date information.
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Notice of Facilities Returning to Service
Once the replacement insulator field work is complete, the field crews will contact Xcel
Energy’s Transmission dispatch center and convey their release of the line. When Xcel
Energy - Transmission determines the facility can safely be returned to full service, Xcel
Energy - Transmission or MISO will post a notice of the system change on OASIS.
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