Standing at an altitude of 345 meters, Zhang Feng and Hu Zi'an, the transmission operation and maintenance personnel of Tongling Power Supply Company of the State Grid, fastened their seat belts and took out binoculars and notebooks from the tool kit. Every movement of high-altitude operation requires them to be careful and precise.

Today, they drove for more than an hour to Xinkai village, Oushan town, Zongyang county, Tongling city, Anhui province, to carry out the special patrol work for the north tower of the Yangtze River long-span line of ± 800 kV Jintang Line before the festival. The ± 800 kV Jintang Line is a "major artery" connecting clean energy in the west and power load in the east. It transmits more than 30 billion kilowatt-hours of electricity every year, which is equivalent to the power generation capacity of more than 9 million metric ton cargo ships loaded with coal on the Yangtze River.

Two days ago, the Tongling Meteorological Station issued a cold wave blue warning detailing that there will be cold wave precipitation in the next 48 hours, and the minimum temperature will fall below zero, with an average wind force of 4 to 5 and gusts of more than 7. In cold wave and rainy weather, transmission lines are prone to ice coating, conductor galloping and other failures, which made the patrol inspection work more urgent before the festival.

"Today, the wind is strong, and there is a dead angle for observation. The UAV shakes seriously, which affects the observation accuracy." Although the UAV has just been used to patrol the tower and line, Zhang and Hu decided to climb the tower to carry out a special patrol to ensure the quality of the patrol.

After putting on their seat belts and checking their tool kits, the elevator sends them up to the 325-meter-high platform, making their eardrums dull and painful. From the elevator exit to the top of the tower, there is a 20-meter-high and 40-meter-long air corridor to climb. In the cold wind, the tower shakes slightly. Zhang and Hu adjust their body weight and move forward with the shaking. Through the steel grating at the foot, the 10,000 ton freighter passing by the river is only the size of a matchbox.

"Check pole 1 insulator."

"Pole 1 insulator surface is intact."

After reaching the top of the tower, Zhang skillfully adjusted the telescope focus, and checked the conductor clamp, shockproof hammer, pin, nut section by section according to the patrol instructions. After confirming that there is no sign of damage or looseness, he moves the lens to the next target.

They chanted one after another, and their voices were blown away by the wind.

By this time, the temperature on the tower has dropped to minus 3 degrees. The wind at the top of the tower is stronger than that on the groundand the chill is felt through their thick winter clothes.

"I can't see clearly from this angle, so I have to change my position." Zhang collected his binoculars and helped the guardrail to move to the other side of the tower. Patrol inspection at each checkpoint takes 1 to 3 minutes, and it takes more time to find suspicious places. "This weather is the most test for people. The worse it is, the more we need to find out about the route." Zhang rubbed his red fingers. "None of the 50 checkpoints can be missed."

After climbing up and down in the morning, they completed the patrol task of the North Tower that day. Their legs became weak from the top of the tower, and as they returned to the car. Zhang immediately turned on the computer and entered the UAV patrol data item by item. "During Spring Festival, the power load must be higher. The more carefully you check today, the more confident you will be during the festival."