
234 Circuit calculations pocket book
(f) Reflected resistance
If a transformer has a resistive load R
L
, as shown in Figure 13.2,
then
R
and
and
Let
fl/AO
2
V/,/Vp
2
7?!
is the value of the effective resistive load presented to the
primary source. It is the value of the resistance reflected from the
secondary into the primary due to the load R
L
. Note that since
iV
2
'Nl
N
2
1
N
2
R
2
= R
L
n where n is the turns ratio
13.3 Maximum power transfer
It was shown in Section 13.2(f) that the reflected resistance from the
secondary to the primary is
and if the turns ratio of the transformer is chosen so that this
resistance is equal to the internal resistanc ...