09,22,2026 16 views
Regardless of the type of inspection, for external clearing, sealing solutions, electrical connections, and vacuum oil injection, they should be carried out according to the process of assembling new transformers, and occasionally more stringent requirements may be required. Similarly, considering that the insulation of the transformer body becomes damp during long-term operation, the time required for vacuum dehumidification will be longer than that of a newly assembled transformer; The sealing structure of the old transformer is outdated, and it requires greater effort to solve the sealing problem.
The author has successfully repaired more than 20 220 kV and 500 kV transformers using "non tedious inspection methods". Comparative experiments were conducted throughout the inspection to confirm that the insulation function did not decrease. Similarly, transformers with longer operating times showed further improvement in insulation function.
"No boring inspection method" means that at present, the transformer inspection does not need to spend a few weeks, using such rare methods on the spot as vortex vacuum drying, hot oil spray vacuum drying, hot oil repeated drying, short circuit vacuum drying and zero sequence current drying, but using the characteristics of bamboo paper insulation exposed in the air for a short time * * * only nominally absorbs moisture and can be removed by vacuuming. After each task day, carry out a dehumidification and moisture-proof annual sequence to maintain the insulation of the body in a dry form at any timeOil immersed experimental transformer
1. Having an environment
a. There is an experienced team of inspectors who work together to understand. b. The fuel tank is constructed with full vacuum. c. There is a crane that can easily lift the upper fuel tank.
d. There is a vacuum solution system capable of achieving high vacuum (≤ 133.3 Pa). e. There is a dry atmosphere generator (or residual polluted nitrogen gas).
2. Excavation method
a. Select sunny colors for inspection tasks during daylight hours.
b. After work, seal the cover and apply vacuum after resuming work at night. Maintain a vacuum degree of ≤ 133.3 Pa while the vacuum pump is gradually turned on.
c. When continuing the task, use a dry atmosphere (or contaminated nitrogen) to eliminate the vacuum.
d. The removed insulation components should be wrapped in plastic bags, filled with a dry atmosphere or nitrogen gas for destruction, and refilled with gas in real time to maintain positive pressure.
e. Newly replaced insulation components or materials can be easily resolved after major issues.
f. When riveting leads, try to avoid freezing with water as much as possible. If this cannot be prevented, use the method of blowing fire air to solve local dryness at any time.
g. After the maintenance task is completed, strict vacuum solution and vacuum oil injection will be carried out.
h. Always conduct complete experiments in accordance with the prevention experiment regulations.
When inspecting, it is necessary to draw on the experience of "small inspections triggering small accidents". For transformers with a voltage rating of 220 kV and above, strict vacuum oil injection must be carried out when draining and returning oil.
