Is there any difference between efficiency of oil-filled and dry-type transformer?

[tipu_sultan]

I have a conservation with someone who told me their performance depends upon the place, location and conditions where they install.
He said generally in open areas (substation open sky) we used dry-type transformers and for closed areas like covered substation we used oil-filled transformer.

He also said that in hospital we used generally dry-type transformers.


I want to know the difference between their performance and efficiency.
And one can how decide which one is best.
Trade-Off of both transformers.

 

[chuckey]

There is no difference in efficiency, that depends only on the copper and iron content.
Oil filled, expensive but weather proof. Dry = cheap.
Frank

 

[schmitt trigger]

oil helps with cooling, specially in transformers that have to be sealed, (like the ones that are exposed to the weather)

 

[tipu_sultan]

If I have a these two type of transformers of rating 1500KVA and have to decide to install in an open area so which one is good?

Fine I got from you is that if I have both type of transformer but have same rating and have the same copper and iron content so their efficiency is same. There is no Trade-off between them. (i.e open sky or inside building).

 

[chuckey]

If you use a dry transformer outdoors, it will get wet!!, so they are mounted under some sort of roof and walls. If they caught fire the heat would take out the building, so you need a CO2 gas flooding system to put the fire out, so you might need some sort of drop shutters to contain the gas.
Thought needs to be had of how the heat losses in the transformer can be accommodate 1 % of 1.5MKVA = 15 KW of heat
If you use an oil filled transformer, it can be sat in a car park with a fence around it, so if it catches fire, the fire does not spread into the building.
Frank

 

[mrinalmani]

Oil transformers are used for large power output capacity. All transformers above 50KVA are generally oil cooled. An oil-cooled transformer is smaller than an air cooled transformer of equal power rating. Oil cooled and air cooled has nothing to do with it being installed outside or inside. I have never seen a dry transformer as large as 1500KVA! This would result in an enormously large design. In fact it is not economically feasible to build such a large transformer without a coolant.

 

[schmitt trigger]

"In fact it is not economically feasible to build such a large transformer without a coolant."

Exactly!!

 

[tipu_sultan]

I have never seen a dry transformer as large as 1500KVA! This would result in an enormously large design. In fact it is not economically feasible to build such a large transformer without a coolant.

So that's why I find only oil-filled transformers on the substations. And from your reason as dry-transformer having same rating as oil-filled have are in greater size.
Anyway
I have also find some type of gas named SF6 used in switchgear to prevent from the arc-flash. I want to know is this gas may be used as a coolant purposes?

Here I have a diagram of substation, in which I find that why the substation have partition and have Air Conditioner [Cooling Unit (CU)] with LV, HV, Battery rack with charger, and DMS RTU on one room while the oil-filled Transformer with CLAUSTRA having no CU on the another.

 

[mrinalmani]

Sulfur hexafluoride is not a coolant. It serves the purpose of a dielectric. The dielectric strength of SF6 is is 2.5 times greater than that of air, consequently the minimum gap required between two terminals of a circuit breaker is reduced by a factor of 2.5, resulting in a smaller design. This is the major advantage of SF6. Other advantages (over air) being faster spark suppressing property and lower sound transmissivity, which results in the reduction of loudness of sound produced during a spark.

 

[schmitt trigger]

Electrical power distribution has been around since the 1890s, and the actual engineering practice is the result of lots of experience.

The materials and practices have evolved to be the safest, most effective and environmental friendly.
For instance, Polychlorinated Biphenyls are no longer used, because of their toxicity although they were extremely efficient transformer coolants.