1. http://nodal.ercot.com 1 Market Trials Outage Scheduling Weekly Update June 25, 2010

2. 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. http://nodal.ercot.com 3 Agenda Anti-trust Admonition Environment Report –Planned / unplanned outages –CIM Load –Known Issues Standing Reports and Updates –General reminders / updates Outage Scheduler Transition to Go-Live Question and Answers / General Discussion 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. Market Trials 2010 Roadmap http://nodal.ercot.com 4

5. http://nodal.ercot.com 5 Day-to-day operations summary: Planned / Unplanned Outages of EDS / CIM Load Planned Outages –06/25/2010 5:00 P.M. – 10:00 P.M. Hardware site failover and application patch deployments are being planned during this period and will affect availability of following application services: –OS UI –OS –EWS Unplanned Outages –No unplanned outages to report Target CIM Load dates for the month of June / July –7/01/2010 – start on 2 week load schedule –7/16/2010

6. http://nodal.ercot.com 6 General reminders / updates ERCOT has developed a user guide along with a web-based user interface training module to introduce the user interface and provide ongoing reference material for end users of the application. The introductory sessions are targeted at personnel from TSPs, QSEs and Resource Entities and are intended to: –Review ERCOT market rules related to outage coordination –Describe roles and responsibilities for ERCOT and market participants –Introduce the use and design of the Outage Scheduler –Demonstrate the basic functions of the Outage Scheduler –Describe the interfaces between the outage scheduler and other Nodal Market applications. TSPs and QSEs are encouraged to send personnel that will either submit or maintain outage information on the Outage Scheduler as well as those that may need to generate reports on outages. The location and schedules of the remaining courses are shown below: Date Time City Address 28-Jun-1009:00 to 15:00Dallas, TX Oncor Energy Plaza 1601 Bryan St. Dallas, TX 75201 15-Jul-1009:00 to 15:00 Houston, TX CenterPoint Energy Energy Control and Data Center 16303 Tomball Parkway Houston, TX 77065

7. http://nodal.ercot.com 7 General reminders / updates Reminder: ERCOT will be opening a window of optional Outage Scheduling testing –Testing will open on 7/1/2010 and close on 7/9/2010 –During this period Outages will be de-coupled from the DAM to allow MPs flexibility to test varying scenarios –MPs should contact ERCOT in advance to coordinate approvals or other scenarios ERCOT will presented the Outage Scheduler Transition Plan at NATF last week (6/23/2010) URL: http://www.ercot.com/calendar/2010/06/20100623-NATFhttp://www.ercot.com/calendar/2010/06/20100623-NATF

8. http://nodal.ercot.com 8 Environment Report: Known Issues Known issues posted to the readiness center at: http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com/readiness/markettrials/os/index.html New / Closed Issues: Next Slide

9. http://nodal.ercot.com 9 Environment Report: Known Issues – Newly Opened

10. http://nodal.ercot.com 10 Environment Report: Known Issues – Closed IssueDescription On the details page, the Reviewer Notes are not formatted and are wrapping around the pageNew reviewer notes are being added to the end of the previous note. Copy outage: button is missing when an outage has a status of rejected. If an outage has been Rejected by ERCOT, the Copy outage button is missing. Does not handle the new error message and the Max_record change from EIP If there are more than ~300 outages that should be displayed, the summary page or Warnings page are blank. Max_record - needs to be added to the EIP definition and limit the records to jboss so it does not time out. There is a limit to the number of outages the OS can return before the request times out. Copy: Recurring should only display when the request type is Planned When an outage other that a Planned outage is copied, the Recurring button may be displayed. Operating Company Pick List- should display the company Name and not the short name Pick list to create outages and to query back outages will require that the TSP know the ERCOT assigned MP short names. Related Equipment Not working When the user picks a line or transformer to be outages, and click the "View" button, the related equipment information is not returning. Opportunity outage is not completeOpportunity outage is not working as expected. OS Reports: Advanced Transmission Outage Schedule Statistics NP3- 406 report requirements specifications are incompleteDue to NOGR 25 the requirements specifications are incomplete OS Reports: Advanced Resource Outage Schedule Statistics NP3-407 report requirements specifications are incompleteDue to NOGR 25 the requirements specifications are incomplete OS Reports Planned vs. Actual Transmission Outage Monthly Statistics (NP3-537 ER) - Update cover sheetUpdate the cover sheet to include the formula. OS Reports Planned vs. Actual Resource Outage Monthly Statistics (NP3-539 ER) - Update cover sheetUpdate the cover sheet to include the formula. OS Reports Planned vs. Actual Resource Outage Annual Statistics (NP3-540 ER) - Update cover sheetUpdate the cover sheet to include the formula.

11. 25 June 2010 Outage Scheduler with Zonal Outage Import Delete all Outages and run Zonal to Nodal Transfer Tool Monday, 8/14. Available for review and submissions Monday afternoon, 8/14. List of Outages not transferred can be provided upon request. Due to sensitive nature of Resource Outages, they will not be transferred by the Transfer tool. If a TSP does not want their zonal outages transferred --- inform ERCOT --- and ERCOT will not transfer them. Outage Scheduler Transition Timeline (slide one of two)

12. 25 June 2010 TSPs and QSEs are requested to enter remaining outages not imported by the start of the 168 hour test (August 31, 2010). TSPs and QSEs should also begin entering outages effective December and beyond to support Go-Live. Outages starting and ending in October and/or November are optional to maintain. TSPs and QSEs required to certify Outages in the Nodal Outage Scheduler by 9/17 for all Outages December and beyond. First production pull of OS data 10/2 for first CRR Auction. TSPs are responsible to ensure that the outages in the Nodal Outage Scheduler are correct Timeline (continued)

13. ERCOT OS Readiness – Nodal Metric EMO3 Nodal Metric EMO3, criteria #1 – “A test of the Outage Management Process is completed” Integration between Outage Scheduler and Outage Evaluation has been tested successfully throughout Market Trials. Outage Coordinators able to approve outages in Outage Evaluation and send data back to the Outage Scheduler. 25 June 2010

14. Nodal Metric EMO3, criteria #2 – “An approved Outage Minimization Plan is implemented” Guideline requests TSPs to limit the submission of outages starting after November 21, 2010 and ending before January 4, 2010 ERCOT recommends removing criteria #2 because Outage Coordinators have sufficient authority to approve/reject outages without a Outage Minimization Guideline. ERCOT OS Readiness – Nodal Metric EMO3

15. Outage Scheduler Protocol Timeline ERCOT proposes that Section 3.1 “Outage Coordination” of the Nodal Protocols will become binding on November 1 st, 2010 (for outages in December and beyond). Allows 30 days necessary for Outage Coordination to review and approve outages that will be effective post Go-Live. Based on the November 1 st, 2010 binding date: Two Market Notices to be sent notifying the Market of the 11/1 effective date of Section 3.1 30 days out 10 day out BOD Approval in September TAC Approval in July or August NATF Review in June and/or July 25 June 2010

16. http://nodal.ercot.com 16 Q&A Q&A / Open Forum