Question

$2000\text{V}-200\text{V},20\text{kVA}$ transformers have $66$ turns in the secondary winding. If $I_P$ and $I_S$ represents primary and secondary full-load current respectively, then : (Neglect the power losses in the transformer)

• A. $I_P=10\text{A}$
• B. $I_P=5\text{A}$
• C. $I_S=50\text{A}$
• D. $I_S=100\text{A}$

Answer 1

Answer: (A), (D)

$I_S=100\text{A}$

Given:
$N_S=66$ turns and the voltage rating is $2000\text{V}-200\text{V},20\text{kW}$, means,

$E_P=2000\text{V}$ and $E_S=200\text{V}$

and power in the primary coil $P_P=20,000\text{W}$

So, $E_P{I}_P=20000$

$\Rightarrow 2000\times I_p=20000$

$\Rightarrow I_P=10\text{A}$

Since, the power loss in the transformer is neglected

$\therefore P_S=P_P=20000$

$\Rightarrow E_S{I}_S=20000$

$\Rightarrow 200\times I_S=20000$

$\Rightarrow I_S=100\text{A}$

Hence, options $\left(A\right)$ and $\left(D\right)$ are correct.