*********** REPLY SEPARATOR ***********
On 7/16/06 at 7:23 AM Tom W8JI wrote:
>> Peter,
>>
>> Exactly! There's not different sizes for different output
>> powers for nothing.
>> Best,
>> Will
>
>Just to be clear, no one is suggesting otherwise.
>
>But a 10kVA transformer design does NOT come up to kVA and
>then start limiting. Much of the previous wording in this
>thread seemed to imply flux density limited power.
>
>I would want people to walk away assuming an XX power rated
>transformer delivers XX watts and then starts to "saturate".
>Basically it just runs hotter and hotter with increased
>load, like there is a reasonably linear series resistor
>inside.
Tom, that's correct. The only way it would burn up would be if more current was
pulled from the secondary than it could supply thus heating the wire hot, or a
higher voltage was applied to the primary. The wire is actually what sets the
power available, the calculations merely size the core to the wire. The only
things that really changes the flux, or area calculations is frequency, area,
number of turns, flux density, and primary voltage. A catch 22 is when one uses
a smaller lamination to save on cost from a larger one making a smaller core
with the same area. Smaller wire has to be used so it will fit in the windows
even though the core is sized for the power and number of turns. This can be
played with some, but at ICAS it's best not to run wire under 750 circular mils
per ampere, and on CCS, not under 1000 cir mil per ampere. The only instance
not would be a low voltage winding which is the main outer coil, and is a
single layer. This like a 12 volt transformer with no o
ther secondaries. This one can be played with more as the heat can escape the
wire easily. If over 1 layer, then the above figures for cir mils apply.
>
>73 Tom
>
>
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Best,
Will
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