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Process and Methods of Transformer Vacuuming

Process and Methods of Transformer Vacuuming

1. The significance and purpose of transformer vacuuming

If impurity gases such as oxygen, nitrogen, carbon dioxide, and water vapor exist inside the transformer, the insulation strength of the transformer will be reduced and the transformer oil may be polluted. Therefore, during the manufacturing process of the transformer, the internal gas must be extracted so that the inside of the transformer is in a negative pressure state, thereby effectively ensuring the insulation performance and service life of the transformer.

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Transformer Vacuum Units

2. Transformer vacuuming method and process

There are generally two ways to evacuate transformers: on-site vacuum and workshop vacuum. On-site vacuum mainly uses the busbar single opening method, which opens the busbar of the transformer, and then uses a vacuum pump to extract the gas inside the transformer. Workshop vacuum is to remove the transformer from the production line and put it into the workshop for vacuum extraction. Workshop vacuum extraction can also be divided into two methods: dry and wet. Wet vacuuming requires the use of a liquid cooler, while dry vacuuming does not.

The transformer vacuuming process is as follows:

(1) Control the vacuuming time: The vacuuming time should be controlled at about 150~180 minutes to ensure that the gas inside the transformer is fully extracted. (Please tell PureTech team that your oil tank capacity of transformer, our professional team will recommend you the suitable model)

(2) Control the vacuum degree: Generally speaking, transformer vacuuming requires a vacuum degree of less than 4×10-3Pa.

(3) Control the pumping rate: The pumping rate refers to the amount of gas pumped from the container in unit time. In order to prevent the materials inside the transformer from overheating, the air extraction rate should not be too fast and is generally controlled below 10L/s (also depends on the capacity of transformer oil tank).

3. Precautions for vacuuming the transformer

(1) A vacuum pump is required to evacuate the transformer. Therefore, it is necessary to ensure that the quality and performance of the vacuum pump meet the requirements to avoid contamination of the transformer oil.

(2) During the vacuum extraction process of the transformer, attention should be paid to temperature control to avoid damage to the transformer material due to excessive temperature.

(3) Extracting vacuum from a transformer requires certain experience and skills. In addition to mastering parameters such as exhaust time and exhaust rate according to the actual situation, it is also necessary to formulate corresponding vacuum extraction plans based on different transformer materials and operating environments.

In short, transformer vacuuming is a key step to ensure the insulation performance and service life of the transformer. During the transformer manufacturing process, vacuum extraction is generally completed by the manufacturer. Before the transformer is put into use, it must be vacuumed again to ensure the normal operation of the transformer.

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