Experimental investigation on the accessing to equalpotential working method on 1000kV UHV compact transmission line

The safety operation of UHV transmission lines is important to the power grid and live working technology is a key method to cope with line components defects or fault without outage plan. In order to ensure the safety of live line workers and electrical equipment, the workers entering into equal-potential must select proper accessing path and satisfy the requirement of minimum complex gaps. Live line maintenance is difficult to conduct on the compact UHV transmission lines due to high tower, heavy line components and compact air gaps of tower windows. Several general methods of entering into equalpotential to work on a suspension tower of EHV/UHV transmission line were introduced in this paper. The safety of access into the tower windows were evaluated through a test at 1:1 ratio scale simulated tower and a mannequin simulating the workers at typical work position. And the discharge characteristics of live working complex gap were determined by the up and down methods of switching impulse voltage discharge. Test results show that the accessing to equal-potential method for suspension tower from the side of tower window and parallel to the line was recommended. It's minimum complex gap is 7.0 m. Meanwhile, the method of striding no more than two insulators along the tension string is adopted to enter into potential working on strain tower. It's minimum complex gap is 6.6 m.