Overhead line system and control method

An overhead line system, comprising:

• a plurality of support posts;
• an overhead line supported by the support posts;
• a winch that lifts the overhead line;
• a suspension device including a plurality of pulleys, the overhead line being hung on the pulley and the suspension device being movable in the air as the winch winds the overhead line;
• another overhead line supported by the support posts;
• a fixing device having a drum and a fixing portion, the fixing portion being fittable to the drum and able to stop rotation of the drum, the other overhead line being fixed to the drum and the fixing device being able to stop lifting or lowering the other overhead line;
• a moving device that is connected to the overhead line and is movable in the air along the other overhead line as the winch winds the overhead line, the suspension device being connected to the moving device via the overhead line;
• a tension sensor that detects tension of the overhead line and the other overhead line;
• and
• a control device having a wireless transmitter, the control device that controls the winch and the fixing device, by sending wireless command signals from the wireless transmitter to the winch and the fixing device, so as to reduce tension of the overhead line when a predetermined condition relating to a tension abnormality of the overhead line is satisfied, and
• wherein:
• the predetermined condition includes a condition that the tension detected by the tension sensor is equal to or higher than a first threshold, and
• when the predetermined condition is satisfied, the control device causes the winch to lower the overhead line, and causes the fixing device to lower the other overhead line until the tension detected by the tension sensor becomes equal to or lower than a second threshold that is lower than the first threshold, such that the moving device and the suspension device are moved down.