Ratios of Instrument Transformers

Electrical Measurements

This set of Electrical Measurements & Measuring Instruments Multiple Choice Questions & Answers (MCQs) focuses on “Ratios of Instrument Transformers”.

1. Transformation ratio of an instrument is defined as ____________
a) ratio of primary to secondary phasor
b) ratio of secondary to primary phasor
c) reciprocal of the primary phasor
d) reciprocal of the secondary phasor

2. For a C.T. the transformation ratio is given by which of the following relation?
a) R = IsIp
b) R = IpIs
c) R = 1Ip
d) R = Ip

3. For a P.T. the transformation ratio is given by which of the following relation?
a) R = VsVp
b) R = 1Vs
c) R = VpVs
d) R = Vp

4. Nominal ratio of an instrument transformer is defined as the __________
a) reciprocal of the rated primary value
b) ratio of rated secondary value to primary value
c) reciprocal of the rated secondary value
d) ratio of rated primary value to secondary value

5. For a C.T. the nominal ratio is given by which of the following relation?
a) Kn = Ip(rated)Is(rated)
b) Kn = Is(rated)Ip(rated)
c) Kn = 1Is(rated)
d) Kn = Ip(rated)

6. For a P.T. the nominal ratio is given by which of the following relation?
a) Kn = Vs(rated)Vp(rated)
b) Kn = Vp(rated)Vs(rated)
c) Kn = 1Vs(rated)
d) Kn = Vp(rated)

7. Ratio correction factor is defined as _________
a) reciprocal of nominal ratio
b) ratio of nominal ratio to transformation ratio
c) ratio of transformation ratio to nominal ratio
d) reciprocal of transformation ratio

8. For a C.T. the turns ratio is defined as the _________
a) n = Np ⁄ Ns
b) n = 1 ⁄ Np
c) n = Ns
d) n = Ns ⁄ Np

9. For a P.T. the turns ratio is defined as the _________
a) n = Np ⁄ Ns
b) n = 1 ⁄ Np
c) n = Ns
d) n = Ns ⁄ Np

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