Question

If \( I_p, I_m, I_s \) are magnetising, primary and secondary currents of current transformer, then approximate phase angle \( \theta \) in degrees between \( I_p \) and reversed \( I_s \) is:

• A. \( \theta = \frac{180}{\pi} \times \left( \frac{I_m}{I_s} \right) \)
• B. \( \theta = \frac{180}{\pi} \times \left( \frac{I_p}{I_s} \right) \)
• C. \( \theta = \frac{180}{\pi} \times \left( \frac{I_s}{I_m} \right) \)
• D. \( \theta = \frac{180}{\pi} \times \left( \frac{I_s}{I_p} \right) \)

Hint:

For CT phase error: Use \( \theta \approx \frac{180}{\pi} \cdot \frac{I_m}{I_s} \) — in degrees.

Answer 1

The Correct Option is A

The phase angle error in a current transformer is approximately given by: \[ \theta = \frac{180}{\pi} \times \frac{I_m}{I_s} \] where \( I_m \) is the magnetizing component.