Importance and types of transformer cooling systems by transformer manufacturer in India, Rajasthan Powergen
The power anddistribution transformer in India manufactured by Rajasthan Powergen has a
cooling system to dissipate the heat generated by a transformer. The more
easily the heat can be dissipated the better it is for the working of the
transformer. Cooling system can increase the load carried by a transformer
without heat damage. When the critical limit of the temperature is reached,
there are chances of failure of transformer as there is ageing of the
transformer’s insulation. Thus the role of cooling system is to increase the
capacity of the transformer to carry load without reaching critical hot spot
temperature.
Auxiliary fans is
the most common type of transformer cooling equipment. These fans keep the
radiator tube cool leading to increased ratings of a transformer .
Maintenance of Cooling
Systems
* Dry-Type
Transformers:For the installation of dry-type transformers, ventilation is of
paramount importance.Also the radiator vents of the transformer should be free
of obstructions to aid heat dissipation.
* Forced Air:
If forced air from a fan is used to control the temperature of a transformer,
the motors of the fans should be checked at regular intervals for lubrication.
* Water cooled
systems: Transformer systems using water for cooling should be checked periodically
to make sure that there is no leakage. Leaks can be checked by raising the
pressure within the cooling system. Other equipments related to a water-cooled
system like the alarm system, water pump and pressure gauges can also be
checked. Make sure to check the water source to ensure it has sufficient flow
and pressure.
*Liquid coolants:
When oil is used as a coolant, the dielectric strength of the oil should always
be checked before putting the transformer is put into use.
Types of Cooling
Systems
For oil immersed
transformers, the types of cooling systems are:
* Oil Immersed
Natural Cooled (ONAN): In this type the core and the windings both are kept
immersed in oil. The transformer is cooled by the natural circulation of this
oil.
** Oil Immersed Air Blast (ONAF): Air is circulated in this cooling system and fans are used for cooling the transformer.
* Oil Immersed
Water Cooled (ONWN): An internal coil is used and water flows through it for
cooling. But it is not used commonly now a days.
* Forced Oil
Air Blast Cooled (OFAF): In this case, cooling is accomplished in two ways. Oil
circulation is facilitated by a pump, and fans are added to the radiators to
provide blasts of air.
* Forced Oil
Natural Air Cooled (OFAN): For this type of cooling, a pump is included within
the oil circuit to aid in oil circulation.
*Forced Oil Water
Cooled (OFWF): In this a pump within the oil circuit forces the oil to
circulate out through a separate heat exchanger in which water flows.
Oil-immersed
naturally cooled (ONAN) is the most reliable type of cooling system, it also
produces minimal noise.
The power and
distribution transformers in India manufactured by Rajasthan Powergen have been
using the forced cooling system for years now. Using cooling system can enhance
the transformer's thermal performance and it also leads to increased shelf life
of the transformer by dissipation of heat.