A power transmission line feeds input power at 2300 ,V to a step … - Vidyadip

MCQ

A power transmission line feeds input power at $2300\,V$ to a step down transfonner with its primary windings having $4000$ turns, giving the output power at $230\,V.$ If the current in the primary of the transformer is $5\,A,$ and its efficiency is $90\%,$ the output current would be......$A$

A
$20$
B
$40$
✓
$45$
D
$25$

✓

Answer

Correct option: C.

$45$

c
Given $: V_{P}=2300\, \mathrm{V}, V_{s}=230\, \mathrm{V}, I_{P}=5\, \mathrm{A}$

$\eta=90 \%=0.9$

Efficiency $\eta=0.9=\frac{P_{s}}{P_{p}} \Rightarrow P_{s}=0.9 P_{p}$

$\mathrm{V}_{\mathrm{s}} \mathrm{I}_{\mathrm{s}}=0.9 \times \mathrm{V}_{\mathrm{P}} \mathrm{I}_{\mathrm{P}} \quad(\because \mathrm{P}=\mathrm{VI})$

${I_s} = \frac{{0.9 \times 2300 \times 5}}{{230}} = 45{\mkern 1mu} {\text{A}}$

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