Transformer Oil Testing Items and Test Significance

Transformer Oil be filled in transformer tank, used to cool the transformer,insure the transformer running with suitable temperature.So, the quality of transformer cooling oil is very important.This article is stated the oil testing items and test significance.

transformer cooler oil
transformer cooler oil

(This kind of oil cooler transformer is called Oil immersed Power Transformer, or oil filled transformer, distribution transformer.The cooling types are Corrugated finwall and Radiators. )

corrugated wall with bottom embossing
corrugated wall with bottom embossing
flange type transformer radiators
flange type transformer radiators

Transformer Corrugated Fins Cooler Wall is made by JTYF Corrugated fins wall Forming /Folding machine,by pressing and shaping steel sheet to folded wall,and weld by JTFY Corrugated fins wall seam auto welding machine.

1.Pressing and Folding Corrugated Fin Cooler Wall by JTFY automatic Corrugated Fins Wall Forming Machine.

CORRUGATED FIN COOLER WALL FORMING &PRESSING
CORRUGATED FIN COOLER WALL FORMING &PRESSING

2. Got Folded Corrugated Fins Radiator

folded corrugated fin wall by transformer cooler forming machine
folded corrugated fin wall by transformer cooler forming machine

3.Welding the Corrugated Finwall Seam by JTFY Automatic Corrugated fin cooler wall seam welding machine.

transformer corrugated cooler wall welding machine
transformer corrugated cooler wall welding machine

4.Got Welded Corrugated Fins Wall Cooler

welded corrugated finwall by JTFY auto fins wall seam welding machine
welded corrugated finwall by JTFY auto fins wall seam welding machine

Following is Transformer Oil Testing Items:

1.Transformer cooling Oil Appearance:

Inspecting the appearance of the running oil, it can be found that there are insoluble sludge, fibers and dirt in the oil. This item should be recorded in routine tests.

2.Transformer Oil Color:

The new transformer cooling oil is usually colorless or light yellow, and the color will gradually deepen in operation. But normally this trend is relatively slow. If the color of oil products is sharply deepened, it is necessary to investigate whether the equipment is overloaded or overheated. If other relevant characteristic test items meet the requirements, they can continue to operate, but monitoring should be strengthened.  

3.Transformer Cooling Oil Moisture:

Moisture is one of the important reasons that affect insulation aging of transformer equipment. The increase of water content in cooling oil and insulating materials will directly lead to the decline of insulation performance and oil aging, which will affect the reliability and service life of the equipment. Strict supervision of water content is an indispensable test project to ensure the safe operation of equipment.

4.Transformer Oil acid value:

The acidic products contained in the oil will increase the conductivity of the oil and reduce the insulation performance of the oil. When the operating temperature is higher (such as above 80 C). It will also promote the aging and corrosion of the solid fibre insulating material and shorten the service life of the equipment. Because the acid value in oil can reflect the aging of oil quality, it is very important to strengthen the supervision of acid value for taking correct maintenance measures.

5.Oxidation stability of Transformer cooler Oil:

The oxidation stability test of cooling oil is an important means to evaluate its service life. Owing to the good oxidation stability of domestic oils and the addition of antioxidants, this project test is usually carried out only for new oils. However, for imported oils, especially oils without antioxidants. This test should be carried out after several years of operation in order to take appropriate maintenance measures and prolong service life.

6.Distribution Transformer oil Breakdown voltage:

Breakdown voltage of transformer cooling oil is a very important monitoring means to test the endurance of ultimate electrical stress of transformer oil. Usually, it mainly depends on the degree of contamination, such as when the water content in oil is high or impurity particles are contained, it has a greater impact on breakdown voltage.

7.Dielectric loss factor of Power Transformer Oil:

The dielectric loss factor is very sensitive to judge the aging and pollution degree of transformer oil. New oil contains less polar impurities, so the dielectric loss factor is very small, generally only 0.01%-0.1% order of magnitude.

But when oil is aged due to oxidation or overheating, or when other impurities are mixed in, the polar impurities and charged colloidal substances gradually increase. And the dielectric loss factor will also increase, and the aging products of oil are very small, which can not be detected by chemical methods. When sensed, the dielectric loss factor can be clearly distinguished. Therefore, the measurement of dielectric loss factor is a common means of cooling oil inspection and supervision, which has special significance.

8.Electrical Transformer Oil Interfacial tension:

The measurement of interfacial tension between oil and water is an indirect and effective method to check the soluble polar impurities in oil caused by aging. In the initial aging stage, the interfacial tension changes rapidly, and then decreases in the middle aging stage. The formation of sludge increases obviously, so this method can also make a reliable judgment on the trend of sludge formation.

transformer cooler oil
transformer cooler oil

9.Transformer Cooler Oil greasy filth:

This method checks the sludge sediments that can be precipitated from the oil when n-heptane is added to the running oil in the dissolved or colloidal state. Because of the different solubility of sludge in new oil and old oil, sludge will precipitate when new oil is infiltrated into old oil. The sludge deposition will affect the heat dissipation performance of equipment. At the same time, it will cause serious corrosion to solid insulating materials and metals, leading to the decline of insulation performance and greater harm. Therefore, sludge precipitation test must be carried out when mixing oil at a ratio of more than 5%.

10.Cooling Oil Flash point:

Flash point is an essential item for the supervision of running oil. The decrease of flash point indicates the production of volatile combustible gases in oil, which are often caused by partial overheating of electrical equipment and thermal cracking of insulating oil caused by arc discharge at high temperature. The failure of the equipment can be detected in time by measuring the flash point. At the same time, for new filling equipment and cooling oil after maintenance, measuring flash point can prevent or discover whether light distillate oil is mixed, thus ensuring the safe operation of equipment.

11.Gas component content in Transformer oil:

Flammable gases in oil are generally produced by partial overheating or discharge decomposition of equipment. If the cause of flammable gas is not identified and eliminated in time, it is very dangerous to the safe operation of equipment. Therefore, it is very effective for eliminating latent faults of transformers to determine gas components in oil by gas chromatography. This project is an indispensable test content in cooling oil operation supervision.

12.Water-soluble acids of Transformer Oil:

Transformer oil is easy to produce low molecular organic acids, such as formic acid and acetic acid, in the primary stage of oxidation, because these acids are water-soluble. When the water-soluble acid content in oil increases (i.e. the pH value decreases), the solid insulating materials and metals will be corroded, and the insulation performance of electrical equipment will be reduced, and the service life of equipment will be shortened.

13.Point of condensation of Oil:

According to China’s climate conditions, transformer oil is classified according to low temperature performance. For example, the freezing points of the three brands 10, 25 and 45 are – 10, – 25 and – 45 C, respectively. Therefore, it is necessary to determine the condensation point for the acceptance of new oil and the mixing of different grades of oil.

14. cooling Oil Volume resistivity:

The volume resistivity of transformer cooling oil is the same as the dielectric loss factor, which can judge the aging degree and pollution degree of cool oil. Water content, contaminated impurities and acidic products in oil can affect the reduction of resistivity.

More information about JTFY Transformer Tanks & Radiators, Corrugated Fin Wall, PLC Full Auto Corrugated Fin Wall Forming Machine & PLC Automatic Corrugated Fin Seam Welding Machines,Hydraulic Decoiler, please feel free to contact with us – EMAIL : cnkylt@aliyun.com WHATSAPP/MOB: +008615195010186

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