PETITION OF SOUTHERN INDIANA GAS AND ELECTRIC COMPANY D/B/A CENTERPOINT ENERGY INDIANA SOUTH (“CEI SOUTH”) FOR APPROVAL OF A CHANGE IN ITS FUEL COST ADJUSTMENT FOR ELECTRIC SERVICE IN ACCORDANCE WITH THE ORDER OF THE COMMISSION IN CAUSE NO. 37712 EFFECTIVE JUNE 18, 1986 AND SENATE BILL NO. 529 EFFECTIVE APRIL 11, 1979