1. http://nodal.ercot.com 1 Market Trials Outage Scheduling Weekly Update June 11, 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 Qualification Update 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 –06/11/2010 8:30 A.M – 11:00 A.M. OS service will be unavailable during this window in order to support application patch installations. –06/12/2010 10:30 A.M – 12:30 A.M. Availability of OS UI service will be interrupted in order to perform patch installations. The corresponding web services functionality will continue to be operational during this time period. Unplanned Outages –06/10/2010 07:55 A.M – 09:00 A.M. OS service availability was impacted as resulted of an application server performance degradation. Users may have encountered timeout errors during this submission window. Target CIM Load dates for the month of June / July –6/10/2010 – completed as scheduled –6/15/2010 – date change from the 16 th to the 15 th –7/01/2010 – start on 2 week load schedule

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 course are shown below: Date Time City Address 22-Jun-1009:00 to 15:00Austin, TX ERCOT Austin 7620 Metro Center Dr. Austin, TX 78744 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 Environment Report: Known Issues Reminder: ERCOT will post known issues every Friday to the readiness center at: http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com/readiness/markettrials/os/index.html New Issues: IssueDescriptionWork Around/Comments TOO which is not approved is not reverted to waiting state after DR Planned End Date is passed If the TSP that submtted the TOO does not take the TOO and the Designated Resource outage Planned End passes, the TOO is not changing back to the waiting (Stage 1) state. Warning late with actual start is not acknowledged even after entering the actual start The "Late with Actual Start" warning is not clearing once the Actual Start has been entered.ERCOT is looking into this issue. on a Forced Extension resource outage, supporting notes can't be added after the Actual End has been entered Once a forced outage has been extended and the Actual End has been entered, Supporting Notes can't be entered to clear the warning. Add Supporing Notes prior to entering the Actual End. Can't add a supporting note to a Group TOO that has been extended to ack the warning message The user can’t enter Supporting Information on an extended Group Transmission Opportunity Outage that has been extended.ERCOT is looking into this issue.

8. Qualification Update 78 / 81 QSEs are qualified (up from 76) 23 / 25 TSPs qualified (No Change) The Outage Scheduler Qualification Dashboard –The dashboard will be updated every Friday at 7pm http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com 8

9. http://nodal.ercot.com 9 Q&A Q&A / Open Forum