 |
| Measurement MCQs |
1. Which of the following can be used/modified for measurement of angular speed?
1. LVDT 2. Magnetic pick-up
3. Tach-generator 4. Strain gauge
Select the correct answer using the code given below.
a. Only 1 and 2
b. Only 2 abd 3
c. Only 3
d. Only 2, 3 and 4
Instrument Transformers multiple choice questions(MCQ)
2. Turn compensation is used in current transformer primarily for reduction
of________.
a. Ratio error, reduction in phase
angle error is incidental
b. Both ratio and phase angle error
c. phase angle error
d. None of these
3. The ratio marked on the
instrument transformers is_________.
a. Transformation ratio
b. Turns ratio
c. Nominal ratio
d. None of the above
4. A 1000/5, 50 Hz current transformer has a
secondary burden comprising a non-inductive impedance of 1.6 Ω. The primary
winding has one turn. Neglecting the leakage reactance and assuming the iron
loss in the core to be 1.5 W at full-load, the ratio error at full load is(the
magnetizing mmf is 100A)______.
a. +2.25%
b. -3.61%
c. +1.61%
d. -1.52%
5. The ratio and phase angle error in potential
transformers may be reduced by________.
a. By not employing turns compensation
b. Increasing the resistance and leakage reactance in the transformer
c. Increasing the exciting current
d. None of the above
6. The size of potential transformers_____.
a. Is same as that of power transformers of the same VA rating
b. Is much greater than that of
power transformers of the same VA rating because they are designed for low
ratio and phase angle errors which require large size cores and winding
conductors
c. Is smaller than that of a power transformer of the same VA rating
d. None of the above
7. In current transformer there are errors caused
because______.
1. There is always a magnetic leakage and
consequently the primary flux linkages are not equal to the secondary flux
linkage
2. The flux density in the core is not a linear
function of the magnetizing force, i.e. the transformer core becomes saturated
3. The transformer input must have a component
which supplies the core losses and I2R losses of transformers
windings due to flow of current I0
4. There is some exciting mmf required by the
primary winding to produce flux and therefore, the transformer draws a
magnetizing current Im
Which of the above statements is/are correct?
a. 1, 3 and 4
b. 2, 3 and 4
c. 1, 2 and 4
d. 1, 2, 3 and 4
8. Wilson compensation is used to_________.
a. Reduce the phase angle error of a
current transformer
b. Reduce the ratio error of a potential transformer
c. Reduce the ratio error of a current transformer
d. Reduce the phase angle error of potential transformer
9. A 250 : 5, current transformer is used along
with an ammeter, if the ammeter reading is 2.7 A, the line current is______.
a. 167 A
b. 0.054 A
c. 135 A
d. 13.5 A
10. The ratio and phase angle error of instrument
transformers depends upon________.
a. Neither the core loss nor the magnetizing component of no-load current
b. Both core loss and magnetizing
component of no-load current I0
c. Magnetizing component of no-load current I0
d. Core loss component of no-load current I0
11. A PT is a device which is_______.
a. Conductively coupled
b. Electrostatically coupled
c. Electromagnetically coupled
d. Electrically coupled
12. The problem of electro-static coupling in a
transformer is accurate at______.
a. High load on the transformer
b. Low frequency
c. Power frequency
d. High frequency
13. Usually, a CT has______.
a. A higher overload capacity that a
PT
b. The same overload capacity as a PT
c. Lower power overload capacity than PT
d. No overload capacity
14. Capacitive potential transformer are
used_______.
a. Because they are cheaper than the electro-magnetic transformers above a
certain voltage range
b. For primary winding phase voltages above 100 kV
c. For keeping the value of transformation ratio constant irrespective of
the burden by making certain adjustment
d. All of the above
15. If the secondary burden of current transformer is
30 VA and secondary current is 5A, then the impedance of the connected load
will be_______.
a. 1.2 Ω
b. 2.4 Ω
c. 0.6 Ω
d. 2.5 Ω
0 Comments
If you have any doubt, feel free to ask.