Transformer Oil Leakage: Causes, Detection, and Solutions

1 The Causes of transformer oil leakage

1.1 Impact of Temperature Variation:?The transformer operates in an environment where temperature fluctuations are significant. The expansion and contraction of the metallic components of the transformer body due to temperature changes lead to decreased elasticity of the sealing gaskets at various connection points. This results in volume shrinkage, consequently causing oil leakage.

1.2 Design Structural Factors:?The total weight of the radiator itself and the internal transformer oil amounts to several thousand kilograms. The connecting flanges and butterfly valves bear significant loads, which are not uniformly distributed across different parts. This imbalance easily results in uneven stress on sealing gaskets, leading to varying degrees of compression in the gaps between flanges. As sealing materials age and deteriorate, leakage becomes more likely.

1.3 Influence of Vibration Frequency: The internal vibration frequencies of the transformer are inconsistent, causing instability in the vibration frequencies of the connecting parts. Prolonged operation may loosen the screws of the connecting flanges, resulting in leakage.

1.4 Issues with Sealing Structure and Sealing Components:?Poor sealing structure design or improper selection or aging of sealing components can lead to leakage.

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2 Methods for Locating Leakage Points

The causes of transformer oil leakage are diverse, and the manifestations vary. During equipment inspection, the first step is to observe whether there are obvious new oil traces on the ground below the transformer installation location. If found, trace the oil traces upward, paying attention to eliminating any erroneous clues. Along this trail, the genuine source of leakage can usually be identified, such as CT terminal bushings, bushing caps, welding points, or gland fittings.

2.1 Observation and Analysis Method:

This method is applied to locate leakage points falling between seepage and major leakage. Typically, such leakage points do not result in dripping oil or may drip infrequently over extended periods. Hence, although there may be no fresh oil traces on the ground, there is usually a patch of oil stains near the leakage point, often with noticeable traces of oil or sludge concentrated around it. By cleaning the oil-stained area and removing paint or welding flux covering the leakage point using a hacksaw blade or other tools, the leakage point can usually be quickly identified.

2.2 Root Cause Tracing Method:

This approach is utilized for pinpointing slow oil seepage points, often arising from tiny weld pores, cracks, or fissures in pipe joints. Typically, these leakage points are surrounded by a small patch of soil or a dense accumulation of soil particles. For this kind of seepage point generally can be used to cut off the saw or other tools on the floating soil dense area for digging roots to find the point, remove its paint, welding flux skin.?If depressions, particularly at the junction of flat weld seams, are discovered, they are usually indicative of leakage points. Combined with the use of a visualizing agent, the leakage position can be promptly identified.

2.3 Chemical Visualization Method:

The oil seepage under the floating soil area is often prone to parts of the cleanup digging point, and the point with acetone wipe, dry after spraying on the developer (developer for the liquid, sprayed when the mist, can be adhered to the seepage point with a variety of complex surfaces, by the wind can be blown by the surface of the adhesion, including pits into white), after a period of time, the white of the seepage place will darken black, the seepage point instantly visible. The visualizer method is not affected by the environment and the location of the seepage point, and the adhesion time is long and easy to remove, so it is a better way to find the seepage point.

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3 Improvement Measures

Depending on the location of the leakage, multiple treatment methods are typically required, primarily including welding and welding-plugging combined measures.

3.1 Welding:

For cases of oil leakage caused by welding or inherent defects in the steel material, the remedy of welding can be employed. When conducting welding with oil present, it should be carried out when the oil leakage is not significant, and the welding location must be below the oil level. If these conditions cannot be met, vacuum pumping can be performed to create negative pressure before welding. However, excessively high vacuum levels should be avoided to prevent the intake of molten iron. During the welding process, finer welding rods should be selected, and care should be taken to clean the oil traces from the welding area to prevent penetration and ignition. For prolonged welding durations, intermittent and rapid spot welding should be employed, with the arc burning time controlled within 10 to 20 seconds. Continuous welding for an extended period should be strictly avoided to prevent burn-through. For pores with severe oil leakage, iron wires or riveting can be used for plugging before welding. When welding near sealing rubber gaskets or other vulnerable components, cooling and protective measures should be taken.

3.2 Adhesive Plugging:

For leakage points unsuitable or inaccessible for electric welding, materials such as rapid leak plugging adhesives can be used for sealing. These adhesives can handle equipment leakage under oil and pressure conditions, offering convenience and versatility. When using adhesive plugging, attention should be paid to understanding the properties, mixing ratios, and operational guidelines of the adhesive. Depending on the leakage situation and temperature, the mixing ratios may need to be adjusted appropriately or rapid curing agents added. Before applying adhesive plugging, the leakage area should be cleaned, polished, and free from impurities such as oil sludge or paint residues. Adhesive plugging should be applied until the adhesive hardens, ensuring no oil seepage.

3.3 Replacement:

The quality of sealing materials significantly affects oil leakage. Poor-quality oil-resistant gaskets should be promptly replaced with qualified sealing gaskets. Additionally, the size and thickness of sealing gaskets can also affect leakage. Improperly sized sealing cords, gaskets, O-rings, etc., should be replaced, and redesign and processing may be necessary to ensure their sealing effectiveness.

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