Conservator-type transformers and hermetically sealed transformers. Both serve the same fundamental purpose—stepping down voltage for distribution—but they are different in design, maintenance requirements also different, and suitability for specific applications.
Three phase conservator-type transformer is a traditional design that uses an external conservator tank to manage the expansion and contraction of transformer oil caused by temperature fluctuations. The conservator is connected to the main tank and partially filled with oil, leaving an air space above it. A breathing system, often equipped with a silica gel breather, allows air to enter and exit the conservator as the oil level changes.
Conservator :The conservator is a tank that is situated at the top of the transformer to allow the oil to expand and contract with heat and cooling. It has an oil level and oil pressure drive to control the steady-state ratio within the transformer.
Breathing System: Breather contains silica gel and when the transformer oil is heated and expands due to different reasons this gel assists in keeping the moisture out of the transformer hence no contamination is caused and oil life is boosted considerably.
Maintenance: Requires regular upkeep, such as silica gel replacement and oil level checks.
Hermetically sealed oil immersed transformer is maintenance-free design that eliminates the need for a conservator tank. hermetically sealed distribution transformer is completely sealed, and oil expansion is managed internally. There are two common designs:
Gas Cushion Design: Uses inert gas (like nitrogen) to accommodate oil expansion.
Diaphragm Design: Employs a flexible diaphragm or bladder to separate oil from air.
Oil Expansion Management: Sealed design with internal mechanisms for oil expansion.
Moisture and Oxygen Protection: Completely sealed, preventing contamination.
Maintenance: Virtually maintenance-free, reducing operational costs.
Differences Between Conservator-Type and Hermetically Sealed Transformers |
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| Feature | Conservator-Type Transformer | Hermetically Sealed Transformer |
|---|---|---|
| Oil Expansion Management | Uses a conservator tank | Sealed design with gas cushion or diaphragm |
| Moisture/Oxygen Ingress | Possible through breather | Completely sealed, no ingress |
| Maintenance | Regular maintenance required | Minimal to no maintenance |
| Lifespan | Shorter due to contamination risk | Longer due to sealed design |
| Applications | Outdoor, larger transformers | Indoor, harsh environments, urban areas |
| Cost | Lower initial cost, higher maintenance | Higher initial cost, lower maintenance |
The choice between a conservator-type and hermetically sealed transformer depends on your specific requirements:
Choose a Conservator-Type Transformer :
You need a cost-effective solution for large-scale outdoor installations.
You have the resources for regular maintenance and monitoring.
The transformer will be installed in a controlled environment with minimal exposure to harsh conditions.
Choose a Hermetically Sealed Transformer :
You require a low-maintenance solution for indoor or urban installations.
The transformer will operate in harsh or humid environments.
You want a longer lifespan and reduced operational costs.
Lower initial cost.
Suitable for large transformers with significant oil expansion.
Easier to repair and maintain in accessible locations.
Maintenance-free operation.
Better protection against moisture and oxygen ingress.
Longer lifespan and higher reliability in harsh conditions.
