Question { 4731 }

how can u determine size of the conductor by knowing the
voltage level

Answer

Yes one could determine the size of the conductor by knowing
the voltage levels and some other factors too.Also the
maximum voltage that can safely be applied to any winding is
determined by the type and thickness of the insulation used.
When a better (and thicker) insulation is used between the
windings, a higher maximum voltage can be applied to the
windings.
To be more specific by equations,
VD= 2*K*I*L/ CSA

WHERE:

VD= VOLTAGE DROP
I= CURRENT
L= DISTANCE OF THE LOAD FROM THE OUTLET (IN FT)
K= 12 FOR COPPER AND 19 ALUMINUM (FOR MAXIMUM TEMP OF 75 DC)
CSA= CONDUCTOR CROSS SECTIONAL AREA IN CIRCULAR MILS.

Question { 9437 }

why the rating of a transformer in kva not in kw.

Answer

kVA is the unit for apparent power. Apparent power consists
of active and reactive power. Active power is the share of
the apparent power which transmits energy from the source
(generator) to the user. Reactive power is the share of the
apparent power which represents a useless oscillation of
energy from the source to the user and back again. It occurs
when on account of some »inertia« in the system there is a
phase shift between voltage and current. This means that the
current does not change polarity synchronous with the
voltage. But the heat generated in a winding as well as the
eddy current losses generated in a transformer core depend
on the current only, regardless of whether it aligns with
the voltage or not. Therefore the heat is always
proportional to the square of the current amplitude,
irrespective of the phase angle (the shift between voltage
and current). So a transformer has to be rated (and
selected) by apparent power.

Question { 7406 }

why cu losses called cu losses.

Answer

Copper loss is the term often given to heat produced by
electrical currents in the conductors of transformer
windings, or other electrical devices.Since most of the
windings we see in practical application are of
copper,copper losses or winding losses are called copper losses.