10 Types of Electrical transformer W.r.t cooling -Electronicsinfos

Types of Electrical Transformer W.r.t cooling

cooling method of transformer

Some energy is dissipated in the form of heat due to different losses. These different losses are eddy current loss, Iron loss, hysteresis loss, winding resistance loss etc Due to heat the transformer efficiency is disturbed. if we do not take action against the heat the transformer is working at a high temperature and maybe the insulation is weak due to heat. we used a different method to cool down the transformer. The different types are described below

Cooling Method of transformers 

  1. Self-air cooled 
  2. Air blast cooled 
  3. Oil-immersed, self-cooled
  4. Oil-immersed, a combination of self-cooled and air blast
  5. oil-immersed, water-cooled
  6. oil-immersed, forced oil cooled
  7. oil-immersed, a combination of self-cooled and water-cooled
  8. oil-forced, air-forced cooled
  9. forced oil, water-cooled
  10. forced oil, self-cooled

Self-air cooled 

The capacity of a Self-air cooled transformer is 1.5MVA to 3MVA. This type of transformer is cool down by atmospheric air. This type of transformer is used in schools, hospitals, shops and shopping centres etc. This type of transformer protects against humidity or resistance. The transformer core or coil is not enclosed in a container. The low-voltage instrument transformer is based on the self-air-cooled transformer.

Air blast cooled 

This type of transformer is called an Airblast transformer and is denoted by AB. This type of transformer is enclosed in a metal box. We enter the air with the help of a blower from bottom to top. This transformer capacity is between 15 MVA to 35 MVA. We circulate the air by the force in the transformer. There are specific loading capacities for this type of transformer.

Oil-immersed, self-cooled

This type of transformer is also called ONAN(Oil Natural Air Natural). It's widely used nowadays because of its simple operation, reliability and simple construction. The manufacturing capacity of this type of transformer is up to 50000 KVA. If we manufacture this type of transformer up to 50000KVA we need more space and quantity of oil so we manufacture normally up to 30000KVA. This type of transformer is enclosed in a metal tank in which the transformer core and windings are immersed in insulating oil. In this type of transformer oil is circulated in the transformer naturally by heat and cold oil so heat is exhausted by this method. The small transformer surface is plane but the large transformer surface is corrugated and consists of external tubes. we also used radiators on large-capacity transformers. The main principle of this type of transformer is the convection method.

Oil-immersed, a combination of self-cooled and air blast

Large transformers are using combinations of self-cooled and air blast methods. The construction of this type of transformer is like an oil-immersed self-cooled transformer. The main difference is just we used blowers with the main tank. This circulating air provides very fast cooling for the transformer. The motor of the blowers is controlled with a thermostat automatic method. The thermostat on the motor circuit and operate the blowers. when the temperature is reached in its normal state thermostat sense this temperature the turn off the motor.

Oil-immersed, water-cooled

if we see large self-cooled transformers their cost is so high that's why we used the oil-immersed water-cooled method. The core and windings are totally immersed in oil but we used cold water in the external tubes so when cold water circulates in the types its absorbs heat so cooling is produced in the transformer. This type of transformer is used in the high voltage transmission lines. This type of transformer is used where water is available in excess quantity and we achieve the head of water easily.  The main disadvantage of this type of transformer is we need a create a water tube system in the transformer and if any leakage has appeared the insulation of oil or transformed it deteriorates.

Oil-immersed forced oil cooled

In this type of transformer, both the core and coil are immersed in oil and cooling is provided by the force method. For this purpose, we use a pressure system that circulates the oil in tubes to provide cooling. This is the latest method that increased the ratings of transformers. In this method, we used a motor that circulates the air. The construction of heat exchangers is like automotive radiator type. This radiator consists of oil-to-heat exchanger tubes in which oil is circulating. The pump rotates the oil fastly up to down.

Oil-immersed, a combination of self-cooled and water-cooled

In this method, The core and windings are immersed in the insulating oils. This is a combination of Self-cooled and water-cooled.

Oil-forced, air-forced cooled

In this method, the heat is exhausted from windings with the help of Blowers. This is a combination of oil-forced and air forces.

Forced oil, water-cooled

This system is used where when we used water as a coolant. we know that water has high heat conductivity and specific heat so that's why we used this method widely. in this method, we used an oil pump between the transformer and heat exchangers. when oil enters heat exchangers the pump increased the pressure of oil in the transformer. heat exchangers are directly connected to the transformer tank. The pressure of cooling water is less than the oil pressure in the heat exchangers. we both separate tubes for oil and water to avoid leakage mixing of water and oil.

Forced oil, self-cooled

In this method, the oil is circulated by the force. For this purpose, we used radiators so oil is easily circulated in the tubes.

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