How to filter water in insulating oil?

The moisture in insulating oil will affect its insulation performance, so filtering moisture is an important step in maintaining the quality of insulating oil. The following are common methods for filtering moisture in insulating oil:

1. Vacuum oil filtration method

- Principle: Use the vacuum environment to lower the boiling point of water and evaporate the moisture at a lower temperature.

- Steps:

1. Heat the insulating oil to an appropriate temperature (usually 50-60°C).

2. Introduce the heated oil into the vacuum tank, and the vacuum pump extracts the air in the tank to form a negative pressure.

3. The moisture evaporates under low pressure and is discharged after condensation through the condenser.

4. The dried oil is filtered through the filter element to remove residual impurities.

2. Adsorption oil filtration method

- Principle: Use adsorbents (such as silica gel, and molecular sieves) to absorb moisture in the oil.

- Steps:

1. Pass the insulating oil through a filter tank filled with adsorbent.

2. The adsorbent absorbs moisture in the oil.

3. ｒｅｐｌａｃｅ or regenerate the adsorbent regularly.

3. Centrifugal separation method

- Principle: Use centrifugal force to separate water and impurities in oil.

- Steps:

1. Inject insulating oil into the centrifuge.

2. High-speed rotation generates centrifugal force, and water and impurities are thrown to the outer wall and discharged through the discharge port.

3. Clean oil flows out from the center.

4. Coalescing oil filtration method

- Principle: Small water droplets are gathered into large water droplets through the coalescing filter element, and then separated through the separation filter element.

- Steps:

1. Oil passes through the coalescing filter element, and small water droplets gather into large water droplets.

2. Large water droplets are separated when passing through the separation filter element.

3. Dry oil flows out.

5. Heating dehydration method

- Principle: Evaporate water by heating.

- Steps:

1. Heat the insulating oil to 60-70°C.

2. Maintain the temperature to evaporate the water.

3. Exhaust water vapor through the exhaust port.

6. Combined filtration method

- Principle: Combine multiple methods (such as vacuum + adsorption) to improve the dehydration effect.

- Steps:

1. Heat the oil and dehydrate it by vacuum.

2. Then use the adsorption filter to further remove residual moisture.

Notes

- Temperature control: Avoid excessive temperature during heating to prevent oil quality deterioration.

- Equipment maintenance: Regularly maintain the filtration equipment to ensure normal operation.

- Oil quality testing: Test the oil quality before and after filtration to ensure that the moisture content meets the standard.

The above methods can effectively remove moisture from insulating oil and restore its insulation performance.