About Oil-Immersed Transformer

0il tank of the oil-immersed transformer
1. Cylinder-type oil tank, mainly used for various small oil immersed transformers and extra large oil immersed transformers.
2. Bell type oil tank, widely used in 110~500kV oil immersed transformer.
3. The fully sealed oil tank, which has only been used in the last few years for 110kV and above oil immersed transformers.

Oil storage cabinet of the oil-immersed transformer
The transformer’s oil conservator has two functions. One is to provide the space for expansion and contraction of the transformer oil in the fuel tank, and the other is to separate the transformer oil from the outer atmosphere, so as to prevent the aging of the transformer oil.
1. The capsule type oil storage cabinet, in which the rubber capsules are used to separate the transformer oil from the external atmosphere, and provide the heat expansion and contraction space for the transformer oil.
2. The diaphragm type oil storage cabinet separates the transformer oil from the external atmosphere with rubber diaphragm and provides the heat expansion and contraction space for the transformer oil.
3. Corrugated oil conservator, the metal expander consisting of metal corrugated sheets will separate the transformer oil from the outer atmosphere, and provide the space for expansion and contraction of the transformer oil. The corrugated type oil storage cabinet is divided into two types of internal oil and external oil, with good internal oil performance, but large volume.

Cooling mode of the oil-immersed transformer
1. Symbols for cooling methods
The first letter: O – mineral oil, K – synthetic insulating liquid, L – insulating gas.
Second letters: N – natural convection cycle, F – forced oil cycle, D – forced guide cycle.
Third letters: A – air, W – water.
Fourth letters: N – natural convection, F – forced circulation (fan, pump).

2. Examples
ONAN – natural cooling
ONAF – wind cooling
OFAF – forced oil cycle air cooling
ODAF – forced oil cycle guided cooling