Top 350+ Solved Electrical Machine 1 MCQ Questions Answer
Q. In the transformer following winding has got more cross-sectional area
a. Low voltage winding
b. High voltage winding
c. Primary winding
d. Secondary winding
Q. A transformer cannot raise or lower the voltage of a D.C. supply because
a. there is no need to change the D.C. voltage
b. a D.C. circuit has more losses
c. Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero
d. none of the above
Q. Primary winding of a transformer
a. is always a low voltage winding
b. is always a high voltage winding
c. could either be a low voltage or high voltage winding
d. none of the above
Q. Which winding in a transformer has more number of turns ?
a. Low voltage winding
b. High voltage winding
c. Primary winding
d. Secondary winding
Q. Efficiency of a power transformer is of the order of
a. 100 per cent
b. 98 per cent
c. 50 per cent
d. 25 per cent
Q. In a given transformer for given applied voltage, losses which remainconstantirrespective of load changes are
a. friction and windage losses
b. copper losses
c. hysteresis and eddy current losses
d. none of the above
Q. A common method of cooling a power transformer is
a. natural air cooling
b. air blast cooling
c. oil cooling
d. any of the above
Q. The no load current in a transformer lags behind the appliedvoltage by an angle ofabout
a. 180°
b. 120"
c. 90°
d. 75°
Q. In a transformer routine efficiency depends upon
a. supply frequency
b. load current
c. power factor of load
d. both (b) and (c)
Q. Which of the following loss in a D.C. generator varies significantly with the loadcurrent ?
a. Field copper loss
b. Windage loss
c. Armature copper loss
d. None of the above
Q. Torque developed by a D.C. motor depends upon
a. magnetic field
b. active length of the conductor
c. current flow through the conductors
d. all above factors
Q. In a manual shunt motor starter
a. over load relay is connected in series and no volt relay in parallel with the load
b. over load relay is connected in paral¬lel and no volt relay in series with the load
c. over load relay and no volt relay are both connected in series with the load
d. over load relay and no volt relay are both connected in parallel with the load
Q. Which of the following steps is likely to result in reduction of hysteresis loss in a D.C.generator ?
a. Providing laminations in armature core
b. Providing laminations in stator
c. Using non-magnetic material for frame
d. Using material of low hysteresis co-efficient for armature corematerial