1. Electromagnetic torque in rotating machines is present when
a) air gap is uniform
b) stator winding alone carries current
c) rotor winding alone carries current
d) both stator and rotor windings carry current
ans. d
2. The interaction torque depends on
a) stator field strength alone
b) both the stator field and rotor field strengths
c) stator field strength and torque angle
d) stator field rotor field strengths and the torque angle
ans. d
3. Armature winding is one in which working
a) flux is produced by field current
b) flux is produced by working current
c) emf is produced by the working flux
d) emf is produced by the leakage flux
ans. c
4. Large synchronous machines are constructed with armature winding on the stator because stationary armature winding
a) can be insulated satisfactorily for higher voltages
b) can be cooled more efficiently
c) have reduced slip ring losses
d) all of the these
ans. d
5. A coil consists of
a) two conductors
b) two coil-sides
c) two turns
d) four turns
ans. b
6. One turn consists of
a) two-coil sides
b) two conductors
c) four conductors
d) four coil sides
ans. b
7. The main advantages of distributing the winding in the slots is to
a) add mechanical strength to the winding
b) reduce the amount of copper required
c) reduce the harmonics in the generated emf
d) reduce the size of the machine
ans. c
8. The distribution factor is defined as the ratio of
a) arithmetic sum of coil emfs to phasor sum of coil emfs
b) phasor sum of emf per coil to the arithmetic sum of the emf per coil
c) phasor sum of coil emfs to the arithmetic sum of coil emfs
d) phasor sum of coil emfs to the per phase voltage
ans. c
9. The main advantage of using fractional-pitch winding is to reduce
a) amount of copper in the winding
b) size of the machine
c) harmonics in the generated emf
d) cost of the machine
ans. c
10. The pitch factor, in rotating electrical machines is defined as the ratio of resultant emf of a
a) full pitched coil to that of a chorded coil
b) full pitched coil to the phase emf
c) chorded coil to the phase emf
d) chorded coil to that of a full pitched coil
ans. d
a) air gap is uniform
b) stator winding alone carries current
c) rotor winding alone carries current
d) both stator and rotor windings carry current
ans. d
2. The interaction torque depends on
a) stator field strength alone
b) both the stator field and rotor field strengths
c) stator field strength and torque angle
d) stator field rotor field strengths and the torque angle
ans. d
3. Armature winding is one in which working
a) flux is produced by field current
b) flux is produced by working current
c) emf is produced by the working flux
d) emf is produced by the leakage flux
ans. c
4. Large synchronous machines are constructed with armature winding on the stator because stationary armature winding
a) can be insulated satisfactorily for higher voltages
b) can be cooled more efficiently
c) have reduced slip ring losses
d) all of the these
ans. d
5. A coil consists of
a) two conductors
b) two coil-sides
c) two turns
d) four turns
ans. b
6. One turn consists of
a) two-coil sides
b) two conductors
c) four conductors
d) four coil sides
ans. b
7. The main advantages of distributing the winding in the slots is to
a) add mechanical strength to the winding
b) reduce the amount of copper required
c) reduce the harmonics in the generated emf
d) reduce the size of the machine
ans. c
8. The distribution factor is defined as the ratio of
a) arithmetic sum of coil emfs to phasor sum of coil emfs
b) phasor sum of emf per coil to the arithmetic sum of the emf per coil
c) phasor sum of coil emfs to the arithmetic sum of coil emfs
d) phasor sum of coil emfs to the per phase voltage
ans. c
9. The main advantage of using fractional-pitch winding is to reduce
a) amount of copper in the winding
b) size of the machine
c) harmonics in the generated emf
d) cost of the machine
ans. c
10. The pitch factor, in rotating electrical machines is defined as the ratio of resultant emf of a
a) full pitched coil to that of a chorded coil
b) full pitched coil to the phase emf
c) chorded coil to the phase emf
d) chorded coil to that of a full pitched coil
ans. d
