At 8:17 p. M., The 35 kV Dongwan substation on the outskirts of Jiangzhou suddenly tripped, plunging three surrounding communities and two factories into darkness. Amidst the piercing fault alarm, Nanmen Qiyana rushed into the main control room on insulated boots, her forehead still stained with sweat from another maintenance point - she had just completed a four-hour circuit transformation in the community, and she still had uneaten meat buns in the pocket of her overalls, and the heat seeped out through the plastic bag.
"Qiyana! The main control screen shows that phase C of the 10-kilovolt outlet cabinet is grounded, and the zero-sequence current exceeds three times the standard. The isolation belt has been pulled on site, but the factory is pressing hard, saying that if the compressor of the freezer is stopped for another half an hour, the loss will be over one million!" Xiao Zhao, the attendant, cried with a cry in his voice, and ran his fingers across the trembling screen, "We checked for half an hour, but could not find the ground fault point. The value measured by the multimeter fluctuated high and low, as if there was interference."
Nanmen Qiyana was not in a hurry to reply. She put on insulating gloves first and quickly slid her fingertips on the fault log on the main control screen. Her eyes passed through the dense parameters, and finally stopped at the small words "15 minutes before the fault occurred, there was a lightning strike record" - the lightning protection grounding grid of the Dongwan Substation was just renovated last year, but she remembered that the construction team buried two less galvanized flat steel at the grounding pole in the northwest corner in order to meet the construction deadline. She mentioned this to the supervisor at the time, but was rejected as "it does not affect the overall performance."
"Xiao Zhao, get the infrared thermometer and clamp ammeter, and ask two people to follow me to the outdoor outlet cabinet. Pay attention to keeping a safe distance. The insulation rod must be checked in place." She put on the safety
