1. Lead from the front Texas Nodal http://nodal.ercot.com 1 EDS Market Call Bi-Weekly Update July 24, 2009

2. Lead from the front Texas Nodal http://nodal.ercot.com 2 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. DISCLAIMER All presentations and materials submitted by Market Participants or any other Entity to ERCOT staff for this meeting are received and posted with the acknowledgement that the information will be considered public in accordance with the ERCOT Websites Content Management Operating Procedure.

3. Lead from the front Texas Nodal http://nodal.ercot.com 3 Agenda Anti-trust Admonition Day-to-day operations summary –Planned and Unplanned ERCOT outages of EDS systems –Future dates of any system upgrades Standing reports and updates –General Reminders –SEM go-live update –Focused Input Testing Question and Answers/General Discussion Deep Dive Topic (different topics each meeting as needed) - No Deep Dive this Week ERCOT asks that Market Participants log into the WebEx session using their company name and then their name. This will allow ERCOT to take roll-call offline

4. Lead from the front Texas Nodal http://nodal.ercot.com 4 Day-to-day operations summary: Planned / Unplanned Outages of EDS Planned Outages –7/26/09 – Reminder: EDS environment will be shut down until the October release. During the outage, ERCOT will continue to support: Nodal Telemetry / Nodal EMS Monthly Nodal State Estimator Reports – ERCOT will work with NDSWG to determine best method of delivery Nodal Sandbox Environment Focused Input Tests will be conducted as scheduled through the remainder of 2009 The following systems will be taken offline: Nodal External Web Services Interface (EWS) Nodal Market Management System (MMS) Nodal Market Manager User Interface Nodal Market Information System (MIS) Nodal Outage Scheduler Nodal Outage Scheduler User Interface Nodal Reporting Services Unplanned Outages –7/16/09 – 9am – Ongoing public Reports Unavailable (un-resolved prior to EDS Shutdown)

5. Lead from the front Texas Nodal Day-to-day Operations Summary: Sandbox Statistics Update Sandbox Upgrade to EIS 1.19 –Sandbox Usage 6 participants actively using the sandbox environment since the 1.19 upgrade 15 Participants configured to use the sandbox –Type of transactions tested vary –Few tests involving Market Info Interfaces –Reminder: Sandbox will be the only Web Services environment available after the 7/26 EDS Shutdown –To be set up for sandbox, send an email to eds3@ercot.comeds3@ercot.com Provide listener URL for notifications Provide email address for notification of your listener not responding

6. Lead from the front Texas Nodal Day-to-day Operations Summary: General Verifiable Cost Update –Simple Cycle > 90 MW Opened for Submissions on June 30, 2009 –Simple Cycle <= 90MW Opens for Submissions on July 31, 2009 –Gas Steam Non-Reheat Boiler Aug 31, 2009 –Additional Submission Windows are provided in the appendix of this presentation –Currently 2 verifiable costs submissions received to date Performance Metrics Survey –NATF will be reviewing a performance survey at the 7/28 meeting (see agenda for specific times) –This survey is design to compile predicted submission frequency and size from Market Participants –This data will be used performing performance-based testing on Nodal systems

7. Lead from the front Texas Nodal http://nodal.ercot.com 7 Single Entry Model (SEM) Go-Live Update 38-days to Nodal SEM Go-Live (TSP Model Change Submission Tool) What is ERCOT doing this week? –Nodalizing the Zonal Model seed (adding RARF data and other nodal attributes) –July 17 Market Notice to USAs for MPIM Roles for NMMS Role available to assign beginning July 28 NMMS_IMM ERCOT to release details and dates in later notice how/when to assign the roles for SEM Go-Live Training enrollment –Completed session/week 5 of 6 weeks of training –Openings available for next week –Post go-live training Sept 23 Populated CIM Model Distribution (to TSPs only per TAC) –Distributed to 6 TSPs –All those that requested the populated CIM XML file to date have received it Communications during the week – NOMCRHelp@ercot.comNOMCRHelp@ercot.com –No significant issues emailed in from TSPs

8. Lead from the front Texas Nodal http://nodal.ercot.com 8 SEM Go-Live Market Engagement Dashboard TO/TDSP Attendance at any of the SEM Market Calls # of Representatives scheduled to take SEM Training # of TDSP users with access to the test SEM environment # test NOMCRs Submitted by TDSPs to the test SEM environment AEP TEXAS CENTRAL COMPANY XXXX BRAZOS ELECTRIC POWER CO OP INC (TDSP) XXXX BROWNSVILLE PUBLIC UTILITIES BOARD (TDSP) XXX BRYAN TEXAS UTILITIES (TDSP) XXXX CENTERPOINT ENERGY HOUSTON ELECTRIC LLC (TDSP) XXXX CITY OF AUSTIN DBA AUSTIN ENERGY (TDSP) XXXX CITY OF COLLEGE STATION (TDSP) X X CITY OF GARLAND (TDSP) XXX CPS ENERGY (TDSP) XXXX DENTON MUNICIPAL ELECTRIC (TDSP) XXXX GEUS (TDSP) X X GOLDEN SPREAD ELECTRIC COOPERATIVE INC (TSP) XXX LCRA TRANSMISSION SERVICES CORPORATION XXXX ONCOR ELECTRIC DELIVERY COMPANY XXX RAYBURN COUNTRY CO OP DBA RAYBURN ELECTRIC (TDSP) XX RIO GRANDE ELECTRIC CO OP (TDSP) SOUTH TEXAS ELECTRIC CO OP INC XXXX TEXAS MUNICIPAL POWER AGENCY XXX TEXAS-NEW MEXICO POWER CO (TDSP) XXXX WEATHERFORD MUNICIPAL UTILITY SYSTEM XX TEX-LA ELECTRIC CO OP OF TEXAS TOTAL: 18739756

9. Lead from the front Texas Nodal http://nodal.ercot.com 9 SEM Go-Live Criteria Dashboard

10. Lead from the front Texas Nodal http://nodal.ercot.com 10 SEM Go-Live Market Notices and Approval Dates Summary of remaining Stakeholder meeting dates for SEM discussion/approval of Go-Live –August –30-day Market Notice - July 31 –TAC - Aug 6 –ROS - Aug 13 –NDSWG - Aug 18 (under consideration for additional meeting) –ERCOT publishes results and sign-off from Directors – Aug 17 –BOD - Aug 18 –10-day Market Notice - Aug 21 –SEM Go-Live - Aug 31

11. Lead from the front Texas Nodal http://nodal.ercot.com 11 Standing reports and updates: Focused Input Testing (FIT) Update Next testing will take place 7/28 – 7/30 Reminder: remaining FIT windows will only review telemetry and state estimator convergence. SCED inputs will be removed from FIT until further notice. ALL TIMES ARE CENTRAL DurationStart date and timeEnd date and time 27 hrs (3x9) July 28 – 8:00 amJuly 30 – 5:00 pm 27 hrs (3x9) Aug 11 – 8:00 amAug 13 – 5:00 pm 27 hrs (3x9) Aug 25 – 8:00 amAug 27 – 5:00 pm 27 hrs (3x9) Sept 8 – 8:00 amSept 10 – 5:00 pm 27 hrs (3x9) Sept 8 – 8:00 amSept 10 – 5:00 pm 27 hrs (3x9) Sept 22 – 8:00 amSept 24 – 5:00 pm

12. Lead from the front Texas Nodal 090010001100120013001400150016001700 Hour Ending Key Numbers: 91% Test Average Convergence; 100% for 14 of 27 Test Hours. The majority of issues were attributable to zonal-nodal mismatches. Day One: On Day One, the average convergence for the test day finished at 91%. Rates of 92% or higher were achieved during 6 of 9 test hours. Notable issues occurred during the following test hours:  Hour Ending (HE) 0900- the hourly convergence rate dipped to 75% as Manual Replacements (MRs) were made to address telemetry issues that accumulated during the non-Business Hours immediately prior to testing.  HE 1300- the hourly convergence dipped to 86% as MRs were made to adjust telemetry values for a failed ICCP link.  HE 1600- the hourly convergence dipped to 75% as MRs were made to adjust telemetry values for a failed ICCP link. http://nodal.ercot.com 12 State Estimator - FIT III Week 11

13. Lead from the front Texas Nodal Day Two: On Day Two, the average convergence for the test day finished at 85%. Rates of 92% or higher were achieved during 5 of 9 test hours. Notable issues occurred during the following test hours:  HE 0900- the hourly convergence dipped to 42% as MRs were made to address telemetry issues that accumulated during the non-Business Hours immediately prior to testing (i.e., same issue as on Day One).  HE 1000- the hourly convergence dipped to 79% as MRs were made to address zonal- nodal mismatches.  HE 1400- the hourly convergence dipped to 82% as MRs were made to address zonal- nodal mismatches.  HE 1700- the hourly convergence dipped to 77% as MRs were made to adjust telemetry values for a failed ICCP link. A nodal database load was performed in the afternoon, but it did not significantly affect SE convergence rates for the test day. http://nodal.ercot.com 13 State Estimator - FIT III Week 11 (continued) 090010001100120013001400150016001700 Hour Ending Note: Code enhancements for the State Estimator software recently exited FAT. The enhancements aim at correcting the reactive capability curve issue that previously limited the software’s ability to recognize MVAR values beyond a pre-defined limit. The enhancements were deployed as part of the July 15 nodal database load and at present appear to be supporting State Estimator convergence as intended.

14. Lead from the front Texas Nodal 09001000 1100 120013001400150016001700 Hour Ending Day Three: On Day Three, The average convergence for the test day finished at 98%. Rates of 92% or higher were achieved during 8 of 9 test hours. Notable issues occurred during the following test hours:  HE 1000- the hourly convergence dipped to 86% as MRs were made to adjust for telemetry not yet mapped in nodal. http://nodal.ercot.com 14 State Estimator - FIT III Week 11 (continued) FIT III Assessment reports will be posted at: http://nodal.ercot.com/readiness/eds3/documents/index.htmlhttp://nodal.ercot.com/readiness/eds3/documents/index.html Note: The final report for FIT III Week 11 will post to the Readiness Center on Tue., July 28, 2009.

15. Lead from the front Texas Nodal LFC3/16/2016 FIT Series WeekDateDay 1Day 2Day 3Average Convergence % for all Test Hours 100% Convergence Achieved FIT IIWeek 1Oct 21 – 23, 200890.1874.1691.8385.3912 of 27 hrs Week 2Nov 04 – 06, 200888.1796.5897.1193.9518 of 27 hrs Week 3Nov 18 – 20, 200887.1784.1982.9184.7612 of 27 hrs Week 4Dec 02 – 04, 200896.0493.3393.4494.2714 of 27 hrs Week 5Dec 16 – 18, 200894.7497.4996.3096.1819 of 27 hrs Week 6Jan 13 – 15, 200996.0094.1295.7895.3015 of 27 hrs Week 7Jan 27 – 29, 200994.0790.1393.2992.4914 of 27 hrs FIT III Week 1Feb 24 – 26, 200975.4578.8692.8582.3909 of 27 hrs Week 2Mar 10 – 12, 200996.8292.9798.4196.0720 of 27 hrs Week 3Mar 24 - 26, 200985.4594.9894.7091.7114 of 27 hrs Week 4Apr 07 - 09, 200997.1392.6097.4495.7221 of 27 hrs Week 5Apr 21 – 23, 200987.4789.8795.6591.0008 of 27 hrs Week 6May 05 – 07, 200994.3494.4791.8793.5613 of 27 hrs Week 7May 19 – 21, 200996.8197.3697.0497.0718 of 26 hrs* Week 8Jun 02 – 04, 200988.4784.0993.2988.6210 of 27 hrs Week 9Jun 16 – 18, 200997.4586.1495.5993.0613 of 27 hrs Week 10Jun 30 – Jul 2, 200994.9189.8986.6690.4911 of 27 hrs Week 11Jul 14 – 16, 200991.0184.7097.4991.0614 of 27 hrs Trends – FIT II & FIT III 15 * One hour was removed from the Week 7 test results to accommodate a nodal database load.

16. Lead from the front Texas Nodal http://nodal.ercot.com 16 The updated 2009 FIT Calendar is posted at: http://nodal.ercot.com/readiness/eds3/documents/r6/eds_3_lfc_fit3_calendar_2009_v2.ppt http://nodal.ercot.com/readiness/eds3/documents/r6/eds_3_lfc_fit3_calendar_2009_v2.ppt The 2009 FIT III Calendar has been updated to include 6 additional tests: 2009 FIT III Calendar for 27-Hour State Estimator Testing Name of FIT III TestTesting DatesPublishing Dates for FIT Report FIT III, Wk 01Feb 24 – 26Mar 10 FIT III, Wk 02Mar 10 – 12Mar 24 FIT III, Wk 03Mar 24 – 26Apr 07 FIT III, Wk 04Apr 07 – 09Apr 21 FIT III, Wk 05Apr 21 – 23May 05 FIT III, Wk 06May 05 – 07May 19 FIT III, Wk 07May 19 – 21Jun 02 FIT III, Wk 08Jun 02 – 04Jun 16 FIT III, Wk 09Jun 16 – 18Jun 30 FIT III, Wk 10Jun 30 – Jul 02Jul 14 FIT III, Wk 11Jul 14 – 16Jul 28 FIT III, Wk 12Jul 28 – 30Aug 11 FIT III, Wk 13Aug 11 – 13Aug 25 FIT III, Wk 14Aug 25 – 27Sep 08 FIT III, Wk 15Sep 08 – 10Sep 22 FIT III, Wk 16Sep 22 – 24Oct 06 FIT III, Wk 17Oct 06 – 08Oct 20 FIT III, Wk 18Oct 20 – 22Nov 03 FIT III, Wk 19Nov 03 – 05Nov 17 FIT III, Wk 20Nov 17 – 19Dec 01

17. Lead from the front Texas Nodal http://nodal.ercot.com 17 Q&A Q&A / Open Forum

18. Lead from the front Texas Nodal http://nodal.ercot.com 18 Appendix

19. Lead from the front Texas Nodal http://nodal.ercot.com 19 Creation of the Nodal Implementation Team (originally presented 6/12/09)

20. Lead from the front Texas Nodal Standing reports and updates Program Update – Creation of the Nodal Implementation Team (NIT) –At its June 4, 2009 meeting, TAC created the Nodal Implementation Team (NIT) which will be a vehicle for stakeholder engagement in the Nodal program. –In preparation for the NIT initial meeting, the TPTF email distribution list has been discontinued and has been replaced by the NIT distribution list (NIT@lists.ercot.com)NIT@lists.ercot.com If you were previously subscribed to the TPTF distribution list, no action is needed as TPTF subscribers were automatically migrated to the NIT distribution list. If you were not previously subscribed to the TPTF distribution list and would like to subscribe to the NIT distribution list, please access the ERCOT distribution list management website at http://lists.ercot.comhttp://lists.ercot.com –Meeting materials, agenda, and WebEx information will be distributed as soon as they are available –First Meeting will take place on Monday, June 22, 2009 9:30 am – 4:30 pm –The NIT Charter was distributed via email to NIT@lists.ercot.comNIT@lists.ercot.com The charter is embedded below for your review:

21. Lead from the front Texas Nodal http://nodal.ercot.com 21 Review of Overall Registration Data Project Schedule (originally presented 5/22/09)

22. Lead from the front Texas Nodal http://nodal.ercot.com 22 Review of Overall Registration Data Project Schedule http://nodal.ercot.com 22 Each window will be broken into 3 iterations with heightening levels of data quality goals All non-PUN RE’s will submit during 1 of 2 windows (except Wind) Each non-PUN RE will request one of the two windows between 5/22/09 and 6/5/09 via email to nodalmarkettransition@ercot.comnodalmarkettransition@ercot.com Some RE’s may be moved to a different window based on volume Planning and Protection data will be rolled in for the remaining windows (see next slide) All Wind resources will submit during the second window 2009 MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Private Use Network Transmission Data Collection Window 1 - Non-Wind* RE’s Transmission / Planning / Protection Data Collection - Iteration 1 - Iteration 2 - Iteration 3 - Iteration 1 - Iteration 2 - Iteration 3 Private Use Network Planning and Protection Data Collection Window 2 - Wind RE’s Transmission and Planning / Protection Data Collection - Iteration 1 - Iteration 2 - Iteration 3 MP-10 Phase 2 Final Validation SEM GO-LIVE 8/31 EIS 1.19 to EDS 8/10 85% Prod Quality 95% Prod Quality 98% Prod Quality 85% Prod Quality 95% Prod Quality 98% Prod Quality 85% Prod Quality 95% Prod Quality 98% Prod Quality Kick Off Market Call

23. Lead from the front Texas Nodal Registration Data Collection Update Iteration 3 of the Private Use Network Transmission Data Collection closes on 5/19/09 Current Production Quality Metric is 96.5% (goal is 98% by 5/19) 5/22/09 9:30AM – 11:00AM ERCOT will host a kick off for the next leg of the Nodal Registration Data Collection project Changes to Load Resource Registration The kick off meeting will cover the following topics: –Transmission data collection (review for non-PUNs / non-Wind) –Planning and Protection data review (inclusive of Private Use Networks) –Review of registration activities for the remainder of 2009

24. Lead from the front Texas Nodal http://nodal.ercot.com 24 Nodal API sub-group Report, by Transaction, Completion Confidence (originally presented on 2/6/09)

25. Lead from the front Texas Nodal http://nodal.ercot.com 25 Standing reports and updates: Nodal API sub-group (originally presented on 2/6/09) TPTF Action – Report, by Transaction, Completion Confidence –Each Transaction will be classified into 3 confidence levels –RED – Confidence low – high risk of change in the 1.18 and/or 1.19 releases –YELLOW – Changes should be limited to non-structural changes (e.g. enumeration changes) –GREEN – Any Changes will be limited to defects. –Note that if there are no changes in 1.18 and significant change in 1.19, a transaction will be marked as RED for both. It will retain that color until all changes are complete.

26. Lead from the front Texas Nodal http://nodal.ercot.com 26 Standing reports and updates: Nodal API sub-group (originally presented on 2/6/09)

27. Lead from the front Texas Nodal http://nodal.ercot.com 27 Standing reports and updates: Nodal API sub-group (originally presented on 2/6/09)

28. Lead from the front Texas Nodal http://nodal.ercot.com 28 Verifiable Cost Submission (originally presented on 4/17/09)

29. Lead from the front Texas Nodal http://nodal.ercot.com 29 Verifiable Cost Submission (originally presented on 4/17) WMS Approved Verifiable Cost Submission Timelines: Simple Cycle Greater than 90MW June 30, 2009 Simple Cycle Less than or Equal to 90MW July 31, 2009 Gas Steam Non-Reheat Boiler Aug 31, 2009 Gas Steam Reheat BoilerSep 30, 2009 Gas Steam Super Critical BoilerOct 31, 2009 Combined Cycle Less than or Equal to 90MW Nov 30, 2009 Combined Cycle Greater than 90MW Dec 31, 2009 Coal, Lignite Jan 31, 2010 Nuclear, Hydro and Renewable Feb 28, 2010 Reciprocating Engines Feb 28, 2010

30. Lead from the front Texas Nodal http://nodal.ercot.com 30 Verifiable Cost Submission ERCOT plans to roll out verifiable cost training: Verifiable Cost Training will cover: –What are Verifiable Costs –What data need to be submitted –Who is required to submit the data forms and supporting information –Where, when and how are Verifiable Costs used Current Plans: –Instructor Led Training during May/June –One session each in Austin, Houston and Dallas Please send any comment to nodaltraining@ercot.comnodaltraining@ercot.com