On Fri, 24 Mar 2006 12:39:21 GMT, "Lloyd E. Sponenburgh"
wrote:


"Richard J Kinch" wrote in message
. ..
writes:

He then asked about what if the transformer was loaded to its maximum.
This is the part I was unsure of, but going back to my memories of AC
circuit analysis I told him that I thought that the VA losses remained
the same for the core and copper losses since the input to the primary
does not change.

Of course it changes. More output current draws more input current.

Actually, core losses don't change much until the core undergoes saturation,
then they go sky high.

But copper loss increases more or less directly with current, but
exacerbated by temperature rise.

LLoyd

Copper loss increases as square of current, further axacerbated by
increased resistance due to temp rise as noted.

Peak core flux density changes very little with load; it actually
goes down a bit with load due to IR drop in the primary. It is
determined by primary voltage and frequency. It it isn't saturated
under noload condx then it won't saturate under load. Core loss may
change slightly with core temperature, not sure how that works with
silicon steel.