pdci tnob north south derate day ahead market ran pdci tnob branch group ttc n direction changed 2572 mw 2544 mw 0100 1200 operating day 8 1 01 reason change work valve group 6 sylmar first applicable hour ahead market run values 0600 iso update changes line rating status sent market operations inquiries please call hour ahead desk system conditions described communication dynamic subject change iso attempted reflect current accurate information available preparing notice system conditions may change suddenly little notice