Functions, Selection, and Maintenance of Transformer Breather and Desiccant Vents

• The Function of Respirators/Moisture Absorbers: The transformer oil reservoir is connected to the atmosphere via a breather to accommodate the thermal expansion and contraction of the insulating oil. The color-changing silica gel inside the breather absorbs moisture and impurities from the air entering the reservoir, preventing the insulating oil from becoming damp or contaminated.
• Why is maintenance necessary?: Once the silica gel is saturated with moisture, it turns from blue to pink and loses its ability to absorb moisture. If it is not replaced or dried and regenerated in a timely manner, the air entering the oil reservoir will carry moisture that comes into direct contact with the insulating oil, accelerating the deterioration of the oil.
• Maintenance Points: Conduct regular inspections to check the color of the silicone gel. If more than two-thirds of the gel has discolored, replace it or dry and regenerate it. When replacing it, ensure that the respirator’s sealing gasket is intact and that the transformer oil level in the oil cup is normal.

1. Structure and Operating Principles of Respirators

The breather is installed at the end of the oil reservoir’s vent pipe. When the oil temperature rises and the oil expands, the air inside the oil reservoir is vented through the breather. When the oil temperature drops and the oil volume contracts, outside air enters the oil reservoir through the breather. Both incoming and outgoing air pass through a layer of silica gel inside the breather—the silica gel adsorbs moisture and impurities from the air before it enters the oil reservoir, ensuring that the incoming air is dry and clean. The oil cup at the bottom of the breather forms a liquid seal, further filtering particulate matter from the air.

2. Maintenance Schedule and Methods

2.1 Inspection of the Silicone Condition—We recommend checking the color of the silica gel during monthly inspections. Normal, dry silica gel is blue; once it has absorbed moisture to capacity, it turns pink or white. If more than two-thirds of the silica gel has changed color, it should be replaced promptly.

2.2 Silicone Regeneration——Used saturated silica gel can be regenerated (restored to its original blue color) by drying it in an oven at the appropriate temperature and can be reused. Refer to the silica gel product instructions for drying temperature and time.

2.3 Grease Cup Maintenance—The transformer oil in the oil reservoir must also be changed regularly. The oil level in the reservoir should be maintained at the marked line; if the oil becomes cloudy or contains impurities, it should be replaced.

3. Frequently Asked Questions FAQ

3.1 Q: Can I still use the silicone after it turns pink?

A: No. A pink color indicates that the silica gel has reached its moisture-absorption capacity. Continued use will cause it to lose its ability to absorb moisture, meaning that air entering the oil reservoir will no longer be dried, putting the insulating oil at risk of becoming contaminated with moisture.

3.2 Q: What are the consequences of a blocked respirator?

Answer: A clogged breather can prevent the air pressure between the oil reservoir and the atmosphere from balancing. When the oil temperature changes, the oil reservoir may develop negative or positive pressure, which in severe cases can cause the oil tank to deform,oil level meterIndicator distortion, or evenGas RelayFalse alarm.

3.3 Q: Can a breather be used on all transformers?

Answer: All oil-immersed transformers equipped with an oil reservoir require a breather or an equivalent air-drying device. Fully sealed transformers do not require a breather.

Disclaimer: The content of this document is provided solely for technical exchange and reference purposes and does not constitute any form of purchase commitment or contractual offer.

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