NOTICE DATE:  October 1, 2010

NOTICE TYPE:  M-B082710-02 Operations

SHORT DESCRIPTION:  Valley SPS #5 and #6 to be disabled

INTENDED AUDIENCE:  ERCOT Market Participants

DAY AFFECTED:  October 4, 2010

LONG DESCRIPTION:  The ERCOT ISO has received a request to disable the Special Protection System (SPS) at the Oncor Valley Plant Switchyard (Oncor SPS # 5 and 6). Valley SPS-5 protects against overloads on the Collin – Anna; Collin – NW Carrolton; Valley - Anna 345kV lines and the Valley 345/138kV autotransformer. Valley SPS-6 protects against overloads at Valley – Payne switch circuits 1 and 2; and Payne – Alla Hubbard 138kV lines. The proposal to disable these SPSs is due to the mothballing of Valley SES generation.

Effective October 4, 2010, these SPSs will be disabled. Further information regarding these SPSs is located in the “Special Protection Systems Information” section of the Planning and Operations Information secure website: http://planning.ercot.com/login/login.

CONTACT:  If you have any questions, please contact your ERCOT Account Manager. You may also call the general ERCOT Client Services phone number at (512) 248-3900 or contact ERCOT Client Services via email at [log in to unmask].

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