On August 27 2018, local time of Ecuador, nine 230kV HV cables of the Ecuadorian Minas-San Francisco Hydroelectric Project was successfully laid in a 440m ventilaton cable shaft with a diameter of 6m, setting a record for laying HV cables in the deepest shaft in both China and Ecuador and making HEI one of the few enterprises with this technology in the world.

Among the nine 230kV HV cables, the longest is 816m and the laying involves high technical requirements and construction difficulties. Particularly, installation of cables in a 440m deep ventilation cable shaft involves great risks and difficulties. In order to overcome these difficulties, HEI Minas Project Department deployed 30 welding platforms for the cable-laying machines in the cable shafts, 24 cable laying machines, lighting and electric power for a 400m deep shaft, 60 sets of square rollers for cable laying and 180 straight pulleys. In order to complete the laying task as soon as possible, the Minas Project Department of HEI established a double-layer protection at the wellhead of the ventilation cable shaft and simultaneously carried out the laying of 230kV cables and the civil construction of the ventilation chamber, saving precious time for power generation of the first unit.