1. Lead from the front Texas Nodal http://nodal.ercot.com 1 EDS 3 Release 5 and 6 Friday Market Updates June 06, 2008

2. Lead from the front Texas Nodal http://nodal.ercot.com 2 Agenda Antitrust Admonition SCED Update –Submissions Update This Weeks’ Submissions Status Next Week’s Activities –Updates / Questions / Reminders LFC Update –System Wide Test Update –6.3 Open Loop Results / Observations –LFC 6.2 Update Q&A / Open Forum Roll Call

3. Lead from the front Texas Nodal http://nodal.ercot.com 3 Antitrust Admonition ANTITRUST ADMONITION ERCOT strictly prohibits Market Participants and their employees who are participating in ERCOT activities from using their participation in ERCOT activities as a forum for engaging in practices or communications that violate the antitrust laws. The ERCOT Board has approved guidelines for members of ERCOT Committees, Subcommittees and Working Groups to be reviewed and followed by each Market Participant attending ERCOT meetings. If you have not received a copy of these Guidelines, copies are available at the Client Relations desk. Please remember your ongoing obligation to comply with all applicable laws, including the antitrust laws.

4. Lead from the front Texas Nodal http://nodal.ercot.com 4 Submission Times for week of 06/02/08 Activities for Week of 06/09/08 –Submit the following prior to the trade date: COP TPO Output Schedule (open to all resources) INC/DEC (DSR resources only) –Submit RT COP adjustments during business hours –Submit RT OS adjustments during business hours 5/31/20086/1/20086/2/20086/3/20086/4/20086/5/2008 87%83% 1885%82%1485%79%1887%81%1996% 2196% 14 COP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOS

5. Lead from the front Texas Nodal http://nodal.ercot.com 5 Updates / Questions / Reminders Static FIP/FOP –FIP: 10.00 –FOP: 22.00 Migration of integrating FIP/FOP to EDS delayed –Testing is still underway –A market notice will be sent with the new date when available EWS 1.14 migrated to EDS environment last night 06/05/08 –EDS environment available again this morning –Currently no new known issues –Full negative testing still occurring in QA –ERCOT will communicate via the Friday market calls if any new issues are found during negative testing

6. Lead from the front Texas Nodal http://nodal.ercot.com 6 Updates / Questions / Reminders Resource Updates –ERCOT completed the next round of RARF updates in MMS –This included resource name changes  impacted QSE’s were notified WAN Testing –Reminder: Private WAN will have nodaleds.ercot.com added to DNS. Change will take place on Monday 6/9 by 11am If MP’s are set up correctly to use the ERCOT WAN DNS – no action is required –If you will not be able to cut over your systems to the private WAN on Monday, please notify eds3@ercot.com with expected dateeds3@ercot.com Goal is to validate our sample capacity tests –Reminder: ERCOT will continue to evaluate whether large reports and MIS will also be available over the WAN –Reminder: If issues are found, ERCOT will roll back the DNS entry and notify the market via a market notice –Reminder: Notifications will remain over the internet only until supporting infrastructure is in place. ETA - TBD

7. Lead from the front Texas Nodal http://nodal.ercot.com 7 LFC 6.3 Update ERCOT will perform another “Open Loop” test –Next open loop test will take place the week of the 16 th –ERCOT is targeting Thursday 6/19 –ERCOT will confirm time / date of test on next Friday’s call and via a market notice Reminder: System Wide Test Updates: –The 2 hour test will occur the week of June 23 rd There will be a WebEx on June 11 th at 10am to review the testing plan Calendar URL: http://www.ercot.com/calendar/2008/06/20080611-EDS3-6http://www.ercot.com/calendar/2008/06/20080611-EDS3-6 This test will occur with or without the CIM Model The 2 hour test will not occur on Monday of that week Closely Monitor ICCP Data starting on June 16th through the completion of the 2 hour test –The next two System Wide tests will have new target dates: 8 hour and the 48 hour test will be dependant on the CIM Delivery ERCOT will continue to update the Market on the Friday update calls with the new dates After successful completion of the 2 hour test, a workshop will be scheduled to discuss the 8 and 48 hour test

8. Lead from the front Texas Nodal http://nodal.ercot.com 8 Telemetry Availability vs Mismatch and Convergence

9. Lead from the front Texas Nodal http://nodal.ercot.com 9 Limits during test period 6/5, 7am – 11am  GTBD within 500-1000MW of HDL (most units deployed as high as possible)

10. Lead from the front Texas Nodal http://nodal.ercot.com 10 Reference LMPs Vs GTBD (6/5)  Compensating for Resources “invisible” to SCED by 7:20 brought LMPs off cap

11. Lead from the front Texas Nodal http://nodal.ercot.com 11 Reference LMPs Vs MCPE (6/5)  Reference LMP comparable to MCPE  LMPs in west zone were lower than reference LMP  Nodal LMP indicative of submitted TPOs – very good

12. Lead from the front Texas Nodal http://nodal.ercot.com 12 LFC Phase II Testing Results for week of 6/2 –LFC 6.2 test Calpine Reliant FPL LFC 6.2 Complete. Submit Questions to LFC@ercot.comLFC@ercot.com

13. Lead from the front Texas Nodal http://nodal.ercot.com 13 Q&A Q&A / Open Forum