Question

The distribution circuit of a residential power line is operated at 2000 V rms. This voltage must be reduced to 240 V rms for use within the residences. If the secondary side of the transformer has 475 turns, how many turns are in the primary?

Answer 1

Answer:

$N_p\approx3958$

Explanation:

In an ideal transformer the relationship between the voltages is proportional to the ratio between the number of turns of the windings. Thus:

$\frac{V_p}{V_s} =\frac{N_p}{N_s}$

Where:

$V_p=Voltage\hspace{3}in\hspace{3}primary\hspace{3}coil$

$V_s=Voltage\hspace{3}in\hspace{3}secondary\hspace{3}coil$

$N_p=Turns\hspace{3}on\hspace{3}primary\hspace{3}coil$

$N_s=Turns\hspace{3}on\hspace{3}secondary\hspace{3}coil$

So, solving for $N_p$

$N_p=N_s*\frac{V_p}{V_s} =475*\frac{2000}{240} =3958.333333\approx3958$