2007 South DC-Tie Emergency Operation TPTF November 27, 2007

November 27, Agenda Current Operations of the DC-Ties Summary of the Schedules flows in the last 12 Months

November 27, ERCOT DC-Ties ERCOT-CFE Operational DC-Ties –Eagle Pass (DC_S, 36 MW) –Laredo Variable Frequency Transformer (DC_L, 100 MW) –Sharyland Railroad (DC_R, 150MW) ERCOT-SPP Operational DC-Ties –North DC_Tie (DC_N, 220 MW) –East DC_Tie (DC_E 600 MW) DC_N 220 MW DC_E 600 MW DC_S 36 MW DC_L 100 MW DC_R 150 MW

November 27, ERCOT DC-Ties -- Operations ERCOT/SPP DC-Ties –Open for commercial transactions and operation ERCOT/CFE DC-Ties –Interim agreement in place with CFE. Addresses emergency assistance through the DC-Tie and BLT Transmission Outages, Supply shortages, voltage deficiencies and other –Currently only utilized under emergency conditions Transmission Emergency Condition EECP

November 27, ERCOT received DC-Tie flows 32 times through the South DC- Ties from October 2006 to August –Each DC-Tie flow corresponds with a declaration of an Emergency Condition. South DC Tie Requests

November 27, Eagle Pass DC-Tie Emergency Assistance Schedules Request for Emergency Assistance: –25 Times due to Transmission Emergency Conditions MonthDays October 06 6 (Outage) November 06 5(Outage) December 06 2(Outage) January 07 5 (Winter Storm) February 07 7(Outage) 2 Times due to EECP, June 18 th, 2007 & August 1 st, 2007

November 27, Other South DC-Tie Emergency Assistance Schedules Laredo VFT DC-Tie Schedules Request for Emergency Energy: –3 Times due to Transmission Emergency Conditions July 16, 17, 18 of 2007 Due to a planned outage of a local RMR unit in the Laredo area. –2 Times due to EECP, June 18 th, 2007 & August 1 st, 2007 Railroad DC-Tie Schedules No emergency schedules in the Tie