NOTICE DATE:  April 14, 2011

NOTICE TYPE:  W-B041411-01 Operations

SHORT DESCRIPTION:  DCS event threshold updated to 1100 MW

INTENDED AUDIENCE:  ERCOT Market Participants

DAY AFFECTED:  April 22, 2011

LONG DESCRIPTION:  ERCOT recently received a higher Real Power Rating than its current most severe single contingency. This change is in accordance with NERC Standard BAL-002-0 Disturbance Control Performance. The revised most severe single contingency for the ERCOT Region is 1375 MW and the corresponding Disturbance Control Standard (DCS) event threshold will be updated to 1100 MW.

This change will become effective on April 22, 2011.

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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dh