Question

Phase angle error is given by ____________

(a) \(\frac{180}{π} [\frac{1}{nI_s}]\) degrees

(b) \(\frac{180}{π} [\frac{I_m}{I_s}]\) degrees

(c) \(\frac{180}{π} [\frac{I_m}{n}]\)degrees

(d) \(\frac{180}{π} [\frac{I_m}{nI_s}]\) degrees

The question was posed to me in an international level competition.

The query is from Errors in Current Transformers topic in division Extension of Instrument Ranges of Electrical Measurements

Answer 1

Right option is (d) \(\frac{180}{π} [\frac{I_m}{nI_s}]\) degrees

The best I can explain: The power measurement in a C.T. leads to phase angle error. Phase angle error is given by the relation

θ = \(\frac{180}{π} [\frac{I_m}{nI_s}]\) degrees

where, θ is the phase angle error

            Im is the magnetising component of the excitation current

       Is is the secondary winding current.