Power Transformer Losses

[CuriousElectron]

Hi Guys,
I was thinking about Fe and Cu losses of a power transformer. Do we expect the iron and copper losses to stay constant over the life of a transformer? I know that the total losses are a function of loading of the transformer, specifically the CU losses that are proportional to I2R losses. If we tested the GSU during commissioning at maximum output and recorded the total losses, do we need to test/record values at regular interval to account for any possible degradation of the material due to age and operation of the unit?
Thanks,
EE

 

[itsmoked]

I would not expect any meaningful change in efficiency in this case. An efficiency test won't show all sorts of things shifting inside the transformer like the normal half-dozen transformer tests that exist and should be done regularly on a maintenance cycle.

Any meaningful loss of efficiency would likely be associated with the cooling system like multiple fans running longer and more frequently because of heat exchangers fins corroding, paint failure, or getting dirty.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[prc]

No, iron and copper losses will not change with age and we need not monitor them. Of course, during the beginning of the last century, iron losses used to increase due to poor quality insulation coatings used over the laminations and poor grain orientation in iron.

 

[bacon4life]

Nope, no need to test.

There could be a very small efficiency impacts from malfunctioning cooling systems do the temperature coefficients of copper and iron. Luckily the coefficients are opposites; higher temperature increases copper losses whereas higher temperature decreases iron losses.

If a transformer has a core ground, extra losses may occur in the core. Such a core ground would be caught with tests much easier to implement that a loss test.