What is Transformer Oil Filtration & Why/When Transformer Oil Filtration is Required?

This article on transformer oil filtration will help you gain an in-depth understanding of why and when transformer oil filtration is required, the specifics of transformer oil filtration procedure, and introduce related products and specifications of transformer oil filtration and dehydration.

Through this article, you will definitely have a deeper understanding of transformer oil filtration.

What is transformer oil filtration?

Transformer oil filtration refers to filtering the transformer oil through an oil purifier. This process can filter and remove various moisture, gas and solid impurity particles in the transformer oil so that the transformer oil can restore its original physical and chemical properties. It can not only reduce the cost of replacing new oil but also maintain the normal operation of the transformer.

Why transformer oil filtration is required?

To understand this problem, first, we need to know what is the role of transformer oil during the operation of the transformer.

1. Transformer oil has good insulating properties. Therefore, the insulating material in the transformer can play a better insulating role in oil than air. This prevents short-circuit accidents due to poor insulation.

2. Transformer oil has better heat dissipation performance than water. It can ensure that the transformer will not cause an accident due to overheating during the operation of the transformer.

3. During the operation of the transformer, arcs may be generated, these arcs will damage the components in the transformer and reduce the service life of the transformer. With its good heat dissipation performance, transformer oil can extinguish arcs at the fastest speed and avoid faults caused by arcs.

Under the action of heat and electric field, transformer oil is gradually oxidized in contact with oxygen to form various oxides, alcohols, aldehydes, acids, etc., and finally forms insoluble colloid and sludge. If the oil contains a small amount of moisture and impurities, it will reduce the dielectric strength.

In short, transformer oil plays an important role in ensuring the safe and stable operation of transformers. In order to ensure that these functions of the transformer oil are effectively played, the purity of the transformer oil must be guaranteed. First of all, the regular oil samples of the transformer oil in normal operation should be tested and analyzed, and the oil should be processed according to the results of the analysis.

When the transformer oil is aging and does not meet the normal operation requirements, the transformer oil should be vacuum filtered and purified. Therefore transformer oil filtration is required.

When transformer oil filtration is required?

The performance of transformer oil can affect the reliability and service life of equipment operation. Strict inspection and supervision of transformer oil is an essential test item to ensure the safe operation of equipment.

Transformer oil testing is to analyze the internal quality and physical and chemical properties of transformer oil through a series of advanced testing methods, according to the quality index and performance of transformer oil, and evaluate the quality of transformer oil. The condition of the transformer oil in the equipment should be regularly tracked and monitored, and the deterioration tendency and pollution caused by the transformer oil should be discovered in time.

Transformer oil testing items include kinematic viscosity, density, pour point, freezing point, flash point, acid value, moisture (trace), water-soluble acid or alkali, breakdown voltage, dielectric loss factor, interfacial tension, etc.

The performance of transformer oil usually has the following requirements:

(1) The density should be as small as possible. In order to facilitate the precipitation of moisture and impurities in the oil.

(2) The viscosity should be moderate. Too large will affect convection heat dissipation, and too small will reduce the flash point.

(3) The flash point should be as high as possible. Generally, it should not be lower than 135℃.

(4) The freezing point should be as low as possible.

(5) The lower the content of impurities such as acid, alkali, sulfur, and ash, the better. In order to try to avoid the corrosion of insulation materials, wires, fuel tanks, etc.

(6) The degree of oxidation should not be too high. The degree of oxidation is usually expressed in acid value, which refers to the amount of potassium hydroxide (mg) required to absorb the free acid in 1 gram of oil.

(7) The stability should not be too low. Stability is usually expressed by the acid value test sediment, which represents the ability of the oil to resist aging.

When the regular inspection of transformer oil does not meet the requirements, transformer oil filtration should be carried out.

How to do oil filtration of transformer?

Different types of oil purifiers can be selected according to specific filtration requirements, such as vacuum oil purifiers for oil filtration of transformer. Advanced equipment and simple operation can help deep filtration of transformer oil and solve the troubles of transformer oil filtration to the greatest extent.

Transformer oil filtration procedure

The online transformer oil filtration procedure is performed by a vacuum oil purifier. During power transformer oil filtration procedure, the transformer oil enters the primary filter under the action of the internal and external pressure difference, and the large particles of impurities in the oil are filtered out in the primary filter. Transformer oil enters the vacuum separator after being heated by a vacuum oil purifier with multi-stage infrared rays. In the vacuum separator, the mist is formed first, and then the film is formed so that the contact area in the vacuum is enlarged hundreds of times the original.

The moisture in the transformer oil is rapidly vaporized and discharged from the vacuum system under the conditions of high pumping speed, high vacuum, and large surface.

The water vapor discharged from the upper part of the vacuum separator is first cooled and dehumidified by the condenser, and then enters the cooler to be cooled again, and the condensed water is discharged into the water storage tank. The gas after being condensed and dehumidified twice is finally discharged into the air by a vacuum pump.

The dry oil in the vacuum separator after vacuum vaporization and dehydration is raised from negative pressure to positive pressure by the oil transfer pump and then discharged from the oil outlet after fine filtration to complete the oil filtration of transformer procedure.

The above is the standard procedure for transformer oil filtration.

What is the process of transformer oil filtration?

1. When the canned oil is drained, connect the oil pipeline, and the vacuum oil purifier will heat the oil temperature by self-circulation. Use an oil filter to clean the hot oil flush oil lines. The inside of the oil storage tank is scrubbed clean, and it can be washed without transformer oil. The flushing oil should be stored separately and marked well.

2. When the barreled oil is drained, use a flat-plate oil filter. Before using the flat oil filter, the interior should be cleaned. The oil pipe extending into the oil drum should be made of galvanized pipe. The front end of the nozzle is processed to 45°, and the nozzles at both ends are polished smoothly. The inside and outside of the galvanized pipe must be cleaned before use. When the barreled oil is extracted to the bottom, check the oil quality at the bottom of the barrel. If there are many impurities, the bottom oil may not be extracted.

3. After the transformer oil arriving at the site is introduced into the oil storage tank with an oil filter, the transformer oil filtration is carried out with a vacuum oil purifier. In order to improve the oil filtration effect, the oil filtration of the oil storage tank should adopt the method of inverted oil filtration. That is, all the oil in one oil storage tank is filtered into another oil storage tank through the vacuum oil purifier, and then filtered from the other oil storage tank into the original oil storage tank. If there are few oil storage tanks on site, use the oil storage tank self-circulation, and do a good job of sealing the oil tank. The outlet temperature of the oil filter should not be lower than 50℃. The filtered transformer oil should be tested with oil samples to determine whether the transformer oil is qualified for purification. Oil samples can be taken from the oil filter sampling valve.

Transformer oil filtration and dehydration

Transformer oil filtration machine

Transformer oil filtration machine

A transformer oil filtration machine is a machine for filtering impurities in deteriorated transformer oil. Mainly used to improve the performance of transformer oil in 66KV to 500KV power transmission and transformation projects. It can effectively and quickly remove trace moisture, gas, impurity particles, etc. in insulating oil, thereby improving the performance of transformers, circuit breakers, cables, and capacitors with insulating systems.

Transformer oil filtration machine specifications

Technical ParameterFlow Rate L/H18003000600090001200018000
 Working Vacuity Pa≤80     
 Working Pressure Mpa≤0.35     
 Temperature Range oC45-65     
 Power Supply  50Hz    380V    3-Phase 4-Wire  (or as requested)     
 Total Power KW163670100150200
 Inlet/Outlet Diameter DN20/2025/2532/3240/4050/5065/65
 Weight Kg6509001200160022003000
Oil Treatment IndexBreakdown Voltage KV≥70 (Spherical electrodes)     
 Water Content ppm≤5     
 Gas Content %≤0.3     
 Filtering Accuracy µm1     

Transformer Oil Dehydration Machine

Transformer Oil Dehydration Machine

Transformer Oil Dehydration Machine effectively and quickly removes excess moisture, trace water, acids, dissolved gases, and particulates from transformer oil. It is suitable for treating old and new transformer oil containing moisture, gas, particles, impurities, and acidic substances, thereby improving the performance of transformer oil.

You can learn more about What is Transformer Oil Purification Procedure/ Transformer Oil Purification Process?

You can contact YUNENG’s customer service staff, and professional staff will recommend the most suitable transformer oil filtration machine for your model according to your needs. And give you the most competitive price on this basis.

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