Qinling crews battle ice to keep power flowing

In February, deep in the Qinling Mountains, Zhou Hongliang and his colleagues at the 110-kilovolt Qinling ice-melting station wrapped up an ice-clearing operation. They rubbed their numb hands and gazed out at snow-covered power transmission lines.

For three to four months each winter, the station sits right in the thick of the freezing zone. Every snowfall sparks a battle against ice accumulation on power conductors, and each ice-melting run keeps the lights on in mountain villages and maintains operation of a critical southwest-bound rail artery.

The station is the first in China built to melt ice on transmission lines carrying electricity. Commissioned in 1972, it has seen dramatic shifts over decades: crews once chipped ice off wires manually, while today smart monitoring systems take the lead. Heating has transitioned from coal to electric.

Built for the railway

Back in the 1970s, the Baoji-Chengdu Railway, China's first electrified trunk line, served as the main artery between southwest and northwest China. Its Qinling section featured a succession of tunnels, tight curves and steep gradients, with train traction heavily reliant on electricity. Ice coating power lines and the subsequent blackouts posed a fatal threat to rail operations.

To tackle the hazard, the Baoji power supply branch of the State Grid designed and led construction of the Qinling ice-melting station. Its single-phase 5,000-kilovolt-ampere auto-transformer, made specifically for ice melting, was the only unit of its kind nationwide at that time.

"The system has two taps," Zhou said. "The 110 kV tap melts ice on the conductors, while the 10 kV tap handles ice on overhead ground wires."

Half a century ago, working conditions at the station were harsh. Communication depended on a dedicated carrier telephone line, and line inspections relied on the naked eye. There were no cameras or drones. Ice-melting decisions were made purely based on experience, and patrols meant trekking along trackless mountain slopes.

Even so, no transmission line under the station's protection has ever suffered ice-induced power outages since commissioning. Zhou recalled these lines once supplied power for all of Baoji city, Fengxian county and the Baoji-Chengdu Railway.

After a 330 kV substation was built in Fengxian, the station's load share dropped to 60 percent. It nevertheless remains the sole power corridor crossing the Qinling Mountains.

Lessons on the mountains

Now in his 50s, Zhou heads both the Qinling transmission maintenance team and the station itself. Having lived and worked here for years, he is the backbone of the site: familiar with the quirks of every piece of equipment and the icing patterns of every line segment.

For the team, the power lines are more than hardware — they are like family requiring constant care. That explains why Zhou initiates ice melting once ice thickness hits 10 millimeters, rather than the preset threshold of 15 millimeters. "Less ice means smaller conductor bounce after de-icing, and less stress on fittings and clamps," he noted.

Zhou has a dual mission: carry forward the dedication of the older generation and pass down hard-earned practical know-how.

Zhang Zhuoli, who joined the team in September 2022, is its youngest operator, aged just 26. A fresh graduate who knew nothing of ice-melting work when he arrived, Zhang  can now operate equipment and complete patrols independently.

During this year's Lunar New Year break, heavy snow swept the Qinling Mountains and ice rapidly built up on power lines. Zhang was on leave but returned immediately upon receiving the emergency call. Late that night, as he watched sensor readings return to normal and conductors stabilize, he grasped the true value of his work.

"If ice had snapped a conductor, the Baoji-Chengdu Railway would have been disrupted," he said. "This job lets me feel I'm making a real difference."

The station no longer keeps a three-person crew on-site throughout winter, but whenever severe weather strikes or an ice alert is issued, everyone heads back up the mountain. "Watch the lines, keep the power flowing" is the mantra handed down by veteran workers. No matter how conditions evolve, Zhou and his colleagues will keep passing this spirit to more young recruits.

Staying through winter

The station's highest point sits more than 2,000 meters above sea level. The 6-kilometer section prone to heavy ice under its oversight takes three to four hours for a round-trip patrol.

The route runs alongside a cliff on one side and a deep gorge on the other, turning slippery after snowfall. Sometimes the team must get out of their vehicles to spread de-icing salt or shovel snow before they can move onward.

In cold, damp conditions, drone blades easily ice over and cause the aircraft to lose control, so manual line patrols remain essential to guarantee safety. After ice-melting operations, surveillance cameras are often shrouded in white mist and cannot accurately assess ice buildup. Crew members must conduct on-site checks to rule out hidden defects.

Daily life is simple. During the coldest spells, water pipes freeze solid, so workers break ice from a nearby stream for water. Their meals mostly consist of potatoes and radishes, yet cooking together is always full of laughter.

This dedication carries extra weight during the Spring Festival. "I was on duty here last Spring Festival," Zhang said. "At least two of us take shifts over the holiday, monitoring sensor data on the internal network and watching ice melt little by little. That gives me peace of mind."

He admits it is hard to be separated from family during the festival. But knowing the railway keeps running and more than 100,000 mountain residents have reliable power makes all the hardship worthwhile.