At 9 o'clock on July 10, the cable operation and maintenance class of the cable operation and inspection center of the State Grid Lanzhou Power Supply Company held a pre-shift meeting to prepare for the special inspection of underground cables.

In order to ensure the safety and reliability of power supply, the cable operation and inspection center of State Grid Lanzhou Power Supply Company organized operation and maintenance personnel to inspect the 1120 Xichuan Tao second line and 1121 Xichuan Tao third line cables.

The inspectors of the cable operation and maintenance team of the cable operation and inspection center of the State Grid Lanzhou Power Supply Company carried out inspections in the 110 thousand volt Xiguan cross cable tunnel, checked the operation status of the fire extinguishing device above the joint, and carried out infrared temperature measurement on the intermediate joint of the cable. Photo by Wang Zhiwei

At 9:30, at the entrance of the 110 thousand volt Xiguan Cross Cable Tunnel, the operation and maintenance personnel arrived at the cable wellhead, installed a safety fence, and opened the manhole cover for mechanical ventilation. Su Weiqiang, the person in charge of the work that day, informed Chang Yongjian and Zhang Yue of the safety precautions.

After checking and confirming that the gas content in the cable tunnel was qualified and safe, Su Weiqiang, Chang Yongjian and Zhang Yue followed the ladder down to enter the 10-meter-deep cable tunnel. The tunnel is about 2.2 meters high and 2 meters wide, so narrow and dark that they have to bend down or crouch down to see the cables.

After arriving at the cable layer, the O&M personnel turn on the lights in the tunnel to fully inspect the cables. During the inspection, they carefully checked the appearance of the cables as they walked, and checked whether the drainage facilities, fire protection facilities and ventilation facilities in the tunnel were in good condition. Subsequently, according to the division of labor, they used clamp ammeters and infrared thermometers to measure the grounding circulation data and temperature of the cable joints one by one.

"Phase A 14.7 degrees Celsius, phase B 14.5 degrees Celsius, phase C 14.1 degrees Celsius!" Su Weiqiang picked up the infrared imaging thermometer to measure the temperature of the middle joint of the cable phase by phase, and Chang Yongjian on the side quickly and accurately recorded the data on the inspection record book.

They stop and go, cooperate with each other, and carefully check whether the cable body, accessories, cross-connect box and grounding device are damaged or deformed; Carefully check the operation of lighting, ventilation, drainage, temperature measurement, fire protection and other systems or equipment in the tunnel; Record the cable temperature, grounding current and other data in detail.

"The voltage is normal!" "The fire extinguisher is in stable condition!" "Fire extinguishing bomb No. 5 is installed normally!" After 2 hours of careful inspection and repeated testing, the cable voltage, current, temperature and other indicators show that everything is normal.

At 11:30, the operation and maintenance personnel completed the inspection of 2.46 kilometers of cables in the tunnel. When they came to the ground, the heat wave rolled in, and the dazzling sunlight pierced people's eyes. They then carried out infrared temperature measurement for the cable terminals of the tower section on the ground.

Since the beginning of the summer, the employees of the cable operation and inspection center of Lanzhou Power Supply Company have regularly inspected the underground cables. At present, they have inspected 84 high-voltage cable lines of 110 kV and above in the supply area, totaling 93.53 kilometers, as well as 326 sets of cable terminals and joints.