NOTICE DATE: May 8, 2012

NOTICE TYPE: M-A040612-03 NPRR

SHORT DESCRIPTION: REMINDER – Implementation details of NPRR434

INTENDED AUDIENCE: ERCOT Market Participants

DAY AFFECTED: Operating Day May 10, 2012

LONG DESCRIPTION: Effective starting on Operating Day May 10, 2012, ERCOT will implement Nodal Protocol Revision Request (NPRR) 434, Increase the Capacity Limitation of a Generation Resource Providing RRS, which was approved by the ERCOT Board on February 21, 2012.

NPRR434 increases the maximum amount of Responsive Reserve (RRS) that can be provided by a Generation Resource from 20% to 24% of its High Sustained Limit (HSL).

The Day-Ahead Market results on May 9, 2012, for Operating Day May 10, 2012, will reflect the increased RRS percentage.

ADDITIONAL INFORMATION: NPRR434 and associated documents can be found on the ERCOT website, under Market Rules, at http://www.ercot.com/mktrules/issues/nprr/426-450/434/index.

Information on upcoming releases can be found on the ERCOT Multi Year Project Priority List (PPL) at http://www.ercot.com/services/projects/.

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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