NOTICE DATE: September 8, 2015

NOTICE TYPE: W-A090815-01 Operations

SHORT DESCRIPTION: New Laredo Generic Transmission Constraint

INTENDED AUDIENCE: ERCOT Market Participants

DAY AFFECTED: September 9, 2015

LONG DESCRIPTION: ERCOT is implementing a new Generic Transmission Constraint (GTC) for the Laredo region. This GTC has been created to address voltage stability concerns that occur under certain system conditions when there is a strong import into the Laredo area. The Laredo GTC is an interface constraint which includes the following transmission lines:

San Miguel – Lobo 345 kV

Holcomb – North Laredo Switch 138 kV

Piloncillo – North Laredo Switch 138 kV

La Quinta – Lobo 138 kV

Rio Bravo – Molina 138 kV

Freer – Lobo 69 kV

The Generic Transmission Limit (GTL) associated with this GTC will be calculated based on the sum of the flows on these lines which feed into the Laredo area. This GTC will be effective as of September 9, 2015, and details associated with this GTC can be found on the ERCOT MIS Secure Area in the “Generic Transmission Constraints” portlet. A Digital Certificate is required to access the MIS.

CONTACT: If you have any questions or comments pursuant to Protocol Section 3.10.7.6 (3) on this GTC, 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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