Transformer ONAN cooling method for the internal oil natural convection cooling, that is commonly referred to as oil-immersed self-cooling.
The cooling mode of the transformer is determined by the cooling medium and the circulation method. Since the oil-immersed transformer is also divided into the internal cooling mode of the tank and the external cooling mode of the tank, the cooling mode of the oil-immersed transformer is represented by four letters.
The first letter: the cooling medium in contact with the winding.
O -------- mineral oil or ignition of more than 300 ℃ of insulating liquid;
K -------- Insulation liquid with ignition point greater than 300 ℃;
L -------- ignition can not be measured insulation liquid;
The second letter: the way the internal cooling medium is circulated.
N -------- The oil flow flowing through the cooling equipment and the windings is a natural thermal convection cycle;
F -------- The oil flow in the cooling equipment is forced to circulate and the oil flow flowing through the windings is the thermal convection cycle;
D -------- The oil flow in the cooling equipment is forced to circulate, at least in the main winding oil flow is forced to guide the cycle;
Third letter: external cooling medium.
A -------- air;
W -------- water;
The fourth letter: the way the external cooling medium is circulated.
N -------- natural convection;
F -------- Forced circulation (fan, pump, etc.).
ONAN refers to the natural cooling of oil. Common have the following cooling methods:
Oil immersion (ONAN);
Oil - air - cooled (ONAF);
Forced oil circulation air conditioning (OFAF);
Forced oil circulating water cooling (OFWF);
Forced to guide oil circulation air cooling (ODAF);
Forced to guide the oil circulating water - cooled ODWF).
This is the transformer cooling mode of the sign, meaning that the internal insulating oil natural circulation, with the external air natural heat transfer.
