Operations at Chicago’s two airports are returning to normal Wednesday after an electrical problem at a regional radar facility forced a shutdown of all incoming and outgoing flights. The three-hour halt on Tuesday resulted in more than 1,120 flight cancellations at O’Hare International and Midway International airports. By early Wednesday, about 100 flights from O’Hare were cancelled and a few dozen more were delayed. There were only minor disruptions at Midway. The shutdown of the Chicago Terminal Radar Approach Control (TRACON) facility in suburban Elgin, Illinois was triggered by a bathroom exhaust fan in a ceiling that overheated and melted insulation on some wires. Smoke entered the facility’s ventilation system and the control room.