What is a fully sealed oil-immersed transformer

A fully sealed oil-immersed transformer, also known as a hermetically sealed transformer, is a type of transformer where the oil and internal components are completely enclosed within the tank, eliminating the need for an oil conservator and breather. This sealed design prevents air and moisture from entering, which protects the insulation oil and windings from degradation, extends the transformer's lifespan, reduces maintenance needs, and often results in a more compact and reliable unit. The tank's corrugated design often allows for the automatic adjustment of oil volume as temperature changes.

Key Characteristics

• Sealed Design:

The transformer tank is completely sealed, preventing any exchange of air or moisture with the external environment.

• No Conservator Tank:

Unlike conventional oil-immersed transformers, fully sealed units do not have a conservator tank.

• Corrugated Tank:

A corrugated tank is often used, as its flexible walls automatically adjust the volume of the oil in response to temperature changes, notes Daelim Belefic and ZT Electric.

• Reduced Oil Degradation:

The absence of air and moisture protects the insulation oil from oxidation and contamination, preserving its dielectric properties and increasing the transformer's service life.

Advantages

• Enhanced Durability:

The sealed design significantly improves durability by protecting the internal components from environmental factors.

• Lower Maintenance:

Minimizes the need for regular maintenance, such as oil checking or replacement, due to the oil remaining uncontaminated.

• Improved Safety:

The sealed design helps to ensure the perfect safety of the transformer by providing complete airproofing and waterproofing.

• Space-Saving:

Often more compact and can be more space-efficient due to the elimination of the conservator tank.

• Environmental Benefits:

Environmentally friendly, producing no deleterious gases and having low noise emissions.