What are the causes of oil leakage in transformers?
Special‑purpose transformers have numerous welds and long weld seams, whereas oil‑immersed special‑purpose transformers are assemblies of various welded and joined components built upon a steel‑plate welded enclosure.
Release date:
2026-03-22
Source:
1. Failure of rubber seals and cracking of welds
Special‑purpose transformers have numerous welds and long weld seams, and oil‑immersed special‑purpose transformers are assemblies of various welding and joining processes built upon a steel‑plate welded enclosure.
A QB-5000/2 oil-immersed traction transformer has more than 70 weld joints, with a total weld length of approximately 20 meters; consequently, there may be numerous potential leakage paths. The primary causes of direct leakage include failure of rubber seals and defects such as weld cracking, porosity, and slag inclusions.
2. Aging, cracking, and deformation of sealant components
Leakage in special transformers frequently occurs at the joints, with over 95% attributable to sealing components.
The quality of a sealing element largely depends on its oil resistance; poor oil resistance leads to accelerated aging, especially at elevated temperatures, where the rate of degradation is even faster. This can readily cause the seal to age, crack, deteriorate, deform, and ultimately fail, resulting in oil leakage from the transformer.
3. Manufacturing Quality of Special-Purpose Transformers
During the manufacturing of special transformers, the large number of weld points on the oil tank, the long weld seams, and the inherent difficulties of welding—as well as factors such as welding materials, welding codes (including classification and characteristics of welding process equipment), procedures, and technologies—can all compromise weld quality. This may lead to defects like porosity, slag inclusions, incomplete fusion, and weld detachment, ultimately resulting in oil leakage in special transformers.
4. The quality of the plate-type butterfly valve is substandard.
Another common leakage point in special‑purpose transformers is the plate‑type butterfly valve. In earlier‑model transformers, the standard plate‑type butterfly valves featured relatively rough and thin sealing surfaces and single‑layer seals—designs that have since been phased out and are highly prone to oil leakage.
5. Improper installation method
The flange joint is uneven, resulting in non-uniform stress on all sides of the sealing gasket during installation. Additionally, human error can lead to uneven tightening of the bolts around the gasket. Furthermore, deformation or misalignment of the flange connection causes one side of the gasket to bear excessive load while the other side experiences insufficient compression, making the under‑compressed side prone to leakage.
Keywords:
Electricity,Transformer
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