Total
losses for the transformer, including winding loss and core
loss per pound of silicon steel at a given flux level, may
be calculated from design data and data furnished by steel
suppliers.
At AMVECO, cross-sections of toroids are ordinarily designed
to render a 60ºC to 65ºC rise. The graph below
illustrates the rise in transformer temperature as the
actual power approaches the transformer's nominal power
rating.
|
Temp
Rise vs. Ratio
|
|
|
|
|
A=With Magnetic shield*
B=Without magnetic shield*
*10mG reading on a 600 VA transformer at idle, energized
with 120V 60Hz at room temperature, using Walker
Scientific field monitor model ELF-660 in the R&D
room. |
VOLTAGE
DROP
The
regulation of toroidal power transformers is expressed by
the following equation:
%Reg = [(Eoc-Efl)/Eoc] x100
Efl = Full load voltage
Eoc = No-Load
Regulation may be improved by using large diameter wire
in the windings or a larger core. This technique is accompanied
by a slight increase in size and cost.
