Why breather cap filled with oil?

A breather cap, frequently utilized in transformers & other electrical equipment, is filled with oil for numerous reasons:

Moisture Absorption Control

The breather cap’s principal function is to avoid moisture from entering the device. The oil in the breather cap functions as a barrier, absorbing moisture from the air before it enters the transformer. This is critical because moisture can weaken the insulating qualities of the transformer oil and insulation system, resulting in poor performance & potential failures.

Dust and Particle Filtration

The oil in the breather cap additionally assist to capture dust and other airborne pollutants. If these impurities reach the transformer, they can damage its internal components. The breather cap filters the air so that only clean, dry air enters the device.

Temperature Stability

The oil helps to maintain the temperature inside the breather cap. Temperature fluctuations may cause the air inside the transformer to expand & contract, resulting in pressure shifts. The oil helps to attenuate these consequences by keeping a more consistent temperature, lowering the likelihood of pressure-related problems.

Enhanced Sealing

The oil generates an additional sealing effect, which aids in the transformer’s internal pressure retention. This is critical to preventing contamination and ensuring the transformer’s efficiency.

Durability of Desiccant

In certain designs, the breather cap incorporates moisture-absorbing desiccants (such as silica gel). The oil coating extends the life of the desiccant by acting as an initial moisture barrier, making sure the desiccant material is effective for a longer period of time.

Prevention of Oxidation

The oil in the breather cap additionally helps to prevent oxidation of the transformer’s interior components by restricting the quantity of oxygen that enters. Oxidation can reduce the insulating characteristics of transformer oil and winding materials.