Question

A current transformer rated 100/5 A has magnetizing and loss components of the exciting current as 1 A and 0.6 A respectively. The secondary winding burden is purely resistive. It's transformation ratio at rated current is

• A. 20.12
• B. 20.20
• C. 19.88
• D. 20.00

Answer 1

The correct option is A 20.12

$\text{Given, turns ratio of CT,}$

$n=\frac{100}{5}=20$

$\text{Secondary rated current,}{I}_s=5A$

$\text{Magnetizing current,}{I}_m=1A$

$\text{Core loss component of exciting current,}{I}_w=0.6A$

$\text{We know that, transformation ratio of CT,}$

$R=n+\frac{I_w}{I_S}=20+\frac{0.6}{5}=20.12$