Silica gel in transformers is primarily used as a desiccant in the breather unit to absorb moisture from the air entering the transformer tank.
Understanding Silica Gel in Transformer Breathers
Transformers need to "breathe" as the volume of the insulating oil expands and contracts with temperature changes. As air enters the transformer tank, it often carries moisture. This moisture is highly detrimental to the transformer's performance and lifespan because it can degrade the insulating oil and the solid insulation materials, potentially leading to electrical breakdowns or flashovers.
This is where silica gel plays a critical role. It is placed inside the breather, a component connected to the transformer's conservator tank (or directly to the main tank in smaller units). The silica gel acts as a powerful drying agent, controlling the level of moisture and prevents it from entering the equipment.
Protecting the Transformer Oil
The presence of moisture significantly reduces the dielectric strength of transformer oil. By absorbing the water vapor from the incoming air, silica gel is mainly useful in protecting the transformer oil from the damaging effects of moisture. Keeping the oil dry helps maintain its insulating properties, which is essential for the safe and efficient operation of the transformer.
Types of Silica Gel Used
Commonly, silica gel blue crystals and orange beads work effectively in this application.
- Blue Silica Gel: Contains Cobalt Chloride as an indicator, which changes color from blue to pink when saturated with moisture.
- Orange Silica Gel: A more environmentally friendly alternative, using an organic indicator that changes from orange to green or colorless when saturated.
The color change serves as a visual indicator, allowing maintenance personnel to know when the silica gel is saturated and needs to be replaced or regenerated (dried).
In summary, the primary function of silica gel in a transformer breather is to ensure that only dry air enters the tank, thereby protecting the vital insulating components, especially the transformer oil, from moisture damage.
