Treatment of Leakage Defects

Transformer leakage is mainly concentrated in the following parts: more than 50% of the total leakage points are radiator interface, flat disc valve cap, radiator stuffy head, connecting flange seal; 16% are casing, porcelain bottle leakage; 12% are gas relay interface leakage. In addition, there are some defects in the process of transformer manufacturing, such as welding seam, sand hole and so on.

The common specific parts and causes of transformer oil leakage are as follows:

1. Valve system, butterfly valve cushion material is not good, installation is not good, oil discharge valve accuracy is not high, thread leakage.

2. There is no sealing or elasticity at the rubber cushion of CT outgoing pile head of high-pressure casing base, which causes leakage at the rubber cushion of connection pile head. The small end ruptures, causing leakage.

3. Leakage caused by non-sealing of rubber pad. Generally, the rubber cushion should be kept elastic when it is compressed by 2/3. With the running time, temperature, vibration and other factors, the rubber cushion is prone to aging, cracking and losing elasticity. Installation of different material of rubber cushion, asymmetric position, eccentricity, will also cause the rubber cushion not sealed.

4. Poor design and manufacture. Oil leakage is caused by the thin blue material and rough processing at the welding points of the flange of the high-pressure casing elevator, the outer surface of the oil tank and the big flange of the oil tank chassis. Transformer section

Oil leakage is the most common defect of oil-immersed transformer, accounting for more than 90% of the total defect of oil-immersed transformer. Generally speaking, the main causes of oil leakage of transformer are five aspects: the statistics of professional and technical personnel of main transformer maintenance, according to the proportion of defect number, oil-immersed main transformer is common.

Oil leakage control at welds:

The causes of the problems are as follows:

The main defects are poor welding quality, virtual welding, de-welding, pinholes and sand holes in the welds. The hidden dangers are exposed when transformers leave the factory due to the covering of flux and paint. In addition, electromagnetic vibration will cause welding vibration cracking and leakage.

Solutions to the problem:

For those leakage phenomena that have already occurred, the first step is to find out the leakage points, which should not be omitted. Continuous cleaning is needed to find the source of the leakage along the oil stain. Water-oil compatibility filler is used to seal the leakage point. After solidification, the purpose of long-term leakage control can be achieved.

2. Oil Leakage in Cast Iron Castings

The causes of the problem are as follows:

Oil leakage is mainly caused by sand holes and cracks in iron castings.

Solutions to the problem:

For crack leakage, drilling crack stop hole is a method of eliminating stress and avoiding extension. According to the condition of cracks, lead wire can be inserted into the leak point or riveted by hand hammer. Then, the leakage point is cleaned with acetone and sealed with water-oil compatible filler and titanium steel glue.