Question

For a P.T. the nominal ratio is given by which of the following relation?

(a) Kn = \(\frac{V_{s(rated)}}{V_{p(rated)}}\)

(b) Kn = \(\frac{V_{p(rated)}}{V_{s(rated)}}\)

(c) Kn = \(\frac{1}{V_{s(rated)}}\)

(d) Kn = Vp(rated)

I got this question in quiz.

This intriguing question comes from Ratios of Instrument Transformers in portion Extension of Instrument Ranges of Electrical Measurements

Answer 1

Right option is (b) Kn = \(\frac{V_{p(rated)}}{V_{s(rated)}}\)

Easiest explanation: In a potential transformer, the transformation ratio is given by the ratio of the magnitude of the actual primary voltage to the magnitude of the actual secondary voltage.

where, R is the transformation ratio

       Vp(rated) is the rated primary winding voltage

       Vs(rated) is the rated secondary winding voltage.