A conservator is an oil storage device used in transformers. Its function is to manage the expansion and contraction of transformer oil due to load variations. When the load increases, the oil temperature rises, causing the oil in the main tank to expand. The excess oil flows into the conservator. Conversely, when the temperature drops, the oil in the conservator flows back into the main tank. This automatic adjustment maintains a consistent oil level in the main tank. Additionally, the conservator reduces the contact area between the transformer oil and the air, thereby minimizing the absorption of moisture, dust, and oxidation residues from the air, which settle in the sediment chamber at the bottom of the conservator. This greatly slows the deterioration of the transformer oil.
Structure of the Conservator
The main body of the conservator is a cylindrical container welded from steel plates, with a capacity of approximately 10% of the main tank's volume. It is mounted horizontally on the top of the main tank, and the oil inside connects to the main tank via a pipeline through a gas relay, allowing the oil level to rise and fall freely with temperature changes. Under normal conditions, the minimum oil level in the conservator should be higher than the elevated base of the high-voltage bushing. For bushings with a communicating structure, the minimum oil level in the conservator should be higher than the top of the bushing. A glass oil level gauge (or oil level indicator) is installed on the side of the conservator to observe changes in the oil level at any time.
Types of Transformer Conservators
Transformer conservators come in three forms: corrugated, bag-type, and diaphragm-type.
Bag-Type Conservator: This uses a rubber bag to separate the transformer oil from the external atmosphere, providing space for thermal expansion and contraction of the oil.
Diaphragm-Type Conservator: A rubber diaphragm separates the transformer oil from the external atmosphere, allowing for the oil's thermal expansion and contraction.
Corrugated Conservator: It uses a metal expansion chamber made of corrugated metal sheets to separate the transformer oil from the external atmosphere and accommodate its thermal expansion and contraction. Corrugated conservators are classified into internal and external oil types, with the internal oil type offering better performance but being larger.
(Source: in-en)