Newnes Circuit Calculations Pocket Book

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 ...