Question

The primary of 200/1 A, 5 VA, 0.8 pf current transformer carries 100 A. The secondary current is 0.495 A. The ratio error of the CT is
1. -1.0%
2. -0.5%
3. +0.5%
4. +1.0%

Answer 1

Correct Answer - Option 1 : -1.0%

Nominal ratio, \({K_n} = \frac{{200}}{1} = 200\)

Actual transformation ratio,

\(R = \frac{{{I_p}}}{{{I_s}}} = \frac{{100}}{{0.495}} = 202.02\)

\(Ratio\;error = \frac{{Nominal\;ratio - Actual\;ratio}}{{Actual\;ratio}} \times 100\)

\(= \frac{{200 - 202.02}}{{202.02}} \times 100\)

= -1%