1. Lead from the front Texas Nodal http://nodal.ercot.com 1 EDS 3 Release 5 and 6 Friday Market Updates Aug 08, 2008

2. Lead from the front Texas Nodal http://nodal.ercot.com 2 Agenda Antitrust Admonition SCED Update –Submission Metrics Update –Updates / Questions / Reminders LFC / State Estimator 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 Metrics Update 8/1/20088/2/20088/3/20088/4/2008 N/A85%17N/A86%16N/A89%18N/A89%18 COP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOS Submit the following for each trade date: –Three Part Offer or Output Schedule EOC only required. Should cover 80 – 120% of cost Min Energy / Start-up may be zero’d out FIP/FOP must Sum to 100% –COP Only required if submitting an Output Schedule No updates in the adjustment period required Note: a COP is also required in order to submit during the adjustment period (this will be changed to a warning in the next release of MMS  MMS4) 8/5/20088/6/20088/7/20088/8/2008 N/A89%14N/A87%17N/A79%16N/A82%13 COP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOS

5. Lead from the front Texas Nodal http://nodal.ercot.com 5 Updates / Questions / Reminders Unplanned Environment Outages –Reports 7/29 – 8/4 LMP Reports not posting to MIS correctly – MMS restart caused posting process to abort and monitors did not alert. Monitors corrected so that the first failed post will send alert. 8/5 9:00AM – 9:10AM – CDR reports unavailable. Root cause under investigation. –MIS / Market Manager / MMS / SCED 8/4 4:20PM – 4:45PM – MIS unavailable due to integration process spawning 100’s of DB connections. Patch is being tested and will deploy in 1 week. 8/6 10:30AM – 11:00AM Updated base points not being sent to SCADA / ICCP. Wind Resource with HSL < LSL (telemetry) causing SCED not to solve. This is resolved in MMS4; monitoring has been modified to alert immediately upon occurrence

6. Lead from the front Texas Nodal http://nodal.ercot.com 6 Updates / Questions / Reminders Notifications over WAN –4 MP’s Volunteered to Test with ERCOT –Testing failed on first MP due to an ERCOT network configuration Configuration change is being reviewed. Estimate change to be implemented by mid-next week –Next Step Repeat testing with test MP group Leave notifications on for test MP group for 1 week If successful – ERCOT will route a market notice At this time, MP’s wanting to receive notifications on the WAN once test completes should send WAN Listener URL’s to eds3@ercot.comeds3@ercot.com Note: ERCOT provides an IP range for MP’s to use and NAT back to their internal IP address to avoid conflicting ranges on the ERCOT side. Your network teams already have this range from your zonal listener  leverage an IP in this range. Technical Communications Workshop –Last day for RSVP and suggested agenda topics is today. –Attendance is now up to 38

7. Lead from the front Texas Nodal http://nodal.ercot.com 7 LFC / State Estimator Update 2 Hour System Wide Test Conducted on 6/25: –ERCOT has completed a summary of the results –Summary is located at: http://nodal.ercot.com/readiness/eds3/documents/index.html http://nodal.ercot.com/readiness/eds3/documents/index.html

8. Lead from the front Texas Nodal http://nodal.ercot.com 8 LFC Update: Focused SE Days Start date and timeEnd date and time August 12 12:00 amAugust 14 11:59 pm August 19 12:00 amAugust 21 11:59 pm August 26 12:00 amAugust 28 11:59 pm September 2 12:00 amSeptember 4 11:59 pm September 8 12:00 amSeptember 12 11:59 pm The following dates have been identified for focused SE input –QSEs and TSPs should meet the protocol requirements in section 3.10.7.5 –Actions: Carefully review protocol section 3.10.7.5 to ensure you are familiar with the requirements. Ensure you have the required staff and support during these times Note: there were QSE’s contacted for issue resolution that were unaware of these activities

9. Lead from the front Texas Nodal http://nodal.ercot.com 9 Focused State Estimator Input Window 8/06/08 Telemetry errors accounted for most of the Convergence errors Mismatch between Zonal & Nodal Generation Some RTU failures were reported A patch to the ERCOT SE will be applied prior to the next test SE results were pending rather then reporting Convergence for the day was 81.72% and SE ran 290 times of 237 were reported as valid

10. Lead from the front Texas Nodal http://nodal.ercot.com 10 Q&A Q&A / Open Forum