Reasons and solutions of switching power supply transformer leakage issue

There are two main reasons: one is in transformer designing and manufacturing process; the other is Improper installation and maintenance of transformers. The main leakage parts of transformers are radiator interfaces, flat butterfly valve caps, casings, porcelain bottles, welds, blisters, flanges and other parts.

 

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Although the leakage of switching power supply transformers is very rare, but it occurs sometime. It may pollute and affect the appearance, even it may threaten the safety of personnel. The leakage for transformers includes air in-out and oil leakage. Let’s see the reasons which cause the leakage.

 Reasons for leakage of switching power supply transformer:

There are two main reasons: one is in transformer designing and manufacturing process; the other is Improper installation and maintenance of transformers. The main leakage parts of transformers are radiator interfaces, flat butterfly valve caps, casings, porcelain bottles, welds, blisters, flanges and other parts.

The main malignant accidents of the power system are mostly the burn accident of the windings and the serious damage to the body of the transformer due to the short circuit of the low voltage inlet of the transformer.

1. Air in and out: The air in and out is an invisible form of leakage. For example, the air in and out of the casing head, the diaphragm of the oil conservator, the glass of the safety airway, the trachoma of the welding seam and the sand inclusion of the steel are all visible. 

2. Classification of oil leakage: The oil leakage of transformers can be divided into two types: internal leakage and external leakage, and external leakage can be divided into welding seam leakage and sealing surface leakage.

(1) Internal leakage: The most common internal leakage is the oil in the oil-filled bushing and the oil in the oil chamber of the on-load voltage regulator switch oil leakage to the transformer body.

(2) External leakage: External leakage is divided into two types: weld leakage and sealing surface leakage.

(3) Weld leakage: Weld leakage is caused by the presence of blisters in the welded part of the steel plate.

 

Fault analysis and solution of switching power supply transformer:

1. Oil leakage at the welding point: there is virtual welding, mainly due to poor welding quality. Desoldering, there are pinholes, sand holes and other defects in the welding seam. Because the transformer is covered with flux and paint when it leaves the factory, hidden dangers are exposed after operation. In addition, due to electromagnetic vibration, the welding will crack and cause leakage. For the leakage phenomenon that has already appeared, first find the leakage point, which cannot be missed. For serious leakage parts, metal tools such as flat shovels or sharp punches can be used to rive the leakage points. After controlling the amount of leakage, the surface of the treatment can be cleaned up. At present, polymer composite materials are often used for curing. After curing, temporary The purpose of managing leakage

2. The seals leak oil. Usually, the seal between the box edge and the box cover is sealed with oil-resistant rubber rods or rubber gaskets. If the joints are not handled properly, it will cause oil leakage failure. The reason for the poor sealing is that some are bound with plastic tapes, and some are directly pressed together by the two ends. Due to the rolling during the installation, the interface cannot be pressed firmly, and the sealing effect cannot be achieved, and oil is still leaking. It can be bonded with Fushilan material to make the joint form a whole, and the leakage of oil can be greatly controlled; if the operation is convenient, the metal shell can also be bonded at the same time to achieve the purpose of leakage control

3. Oil leakage at the connection: the fastening bolts are loose and the surface is uneven. The installation process is incorrect, so that the bolts are not fastened well, resulting in oil leakage. After the loose bolts are tightened, the sealing treatment is carried out, and the bolts that may leak are also treated. To achieve the purpose of complete control, the loose bolts must be tightened in strict accordance with the operation process.

4. Oil leakage from iron castings: The main reason for oil leakage is that there are blisters and cracks in the iron castings. Drilling crack prevention holes is the best way to eliminate stress and prevent extension. The treatment can be based on the crack situation. Crack leakage. The leakage point is driven into lead wire or riveted with a hand hammer. The leak was then cleaned with acetone and sealed with material. Casting trachoma can be directly sealed with material.

5. Oil leakage from bolts or pipe threads: poor sealing and rough processing at the factory. The oil leakage fault occurs after the transformer has been sealed for a period of time. Use polymer material to seal the bolts to achieve the purpose of controlling leakage. Another method is to unscrew the bolts (nuts), apply Fushilan mold release agent on the surface, and then apply the material on the surface to tighten them. After curing to achieve governance

6. Oil leakage of radiator: The radiator pipe of the radiator is usually made of seamed steel pipe after being flattened and made by stamping. Oil leakage often occurs in the bending part and the welding part of the radiator pipe. This is because when the radiator pipe is stamped, the outer wall is under tension and the inner wall is under pressure, resulting in residual stress. Close the upper and lower flat valves (butterfly valves) of the radiator to isolate the oil in the radiator from the oil in the tank, reducing pressure and leakage. After determining the leakage site, carry out proper surface treatment, and then use FuShilan material for sealing treatment.

7. Oil leakage from porcelain bottles and glass oil markers: usually caused by improper installation or seal failure, polymer composite materials can well bond metals, ceramics, glass and other materials, so as to achieve the fundamental control of oil leakage.

CB Magnetics is specializing in the production, research, development and sales of high-frequency transformers, low-frequency transformers, inductors, filters, and flat wire common mode inductors. The models include EDR, ED, EQ ultra-thin series transformers, PQ, EE medium power transformers, ER, ETD high power series transformers, all products meet the latest ROHS requirements. Our company has experienced bobbin designing engineers, magnetic core designing engineers, transformer development R&D team, we focus on making your ideals into real products.

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