Question

Phase angle error is due to _________

(a) C.T.

(b) magnetising component

(c) iron loss

(d) supply voltage

I got this question by my school principal while I was bunking the class.

Origin of the question is Errors in Current Transformers topic in section Extension of Instrument Ranges of Electrical Measurements

Answer 1

Right choice is (b) magnetising component

The best I can explain: We know that the phase angle error in a C.T. 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

It is observed from the equation for the phase angle error that it depends on the magnetising component of the excitation current.