Alternator MCQ | Synchronous Generator MCQ

171. Armature reaction AT of a synchronous generator supplying power at rated voltage with zero power factor lagging is

1. Magnetizing
2. Demagnetizing
3. Cross-magnetizing
4. Both magnetizing and cross-magnetizing

172. Consider the following:

1. L.P.F. method
2. E.M.F. method
3. Z.P.F. method
4. M.M.F. method

Which of the above methods are correct for determination of voltage regulation of an alternator?

1. ii, iii and iv
2. i, ii and iii
3. iii and iv only
4. ii and iii only

173. Transient stability of a 3-phase power systems having more than one synchronous generator is not affected by which one of the following specifications?

1. Initial operating conditions of generators
2. Quantum of large power disturbance
3. Fast fault clearance and reclosure
4. Small changes in system frequency

174. Consider the following statements:

EMF induced per phase in an alternator depends on

1. Frequency
2. Number of turns per phase
3. Pitch factor
4. Distribution factor

Which of these statements is/are correct?

1. i only
2. i, ii, iii and iv
3. ii and iii only
4. iii and iv only

175. A salient pole synchronous generator delivering power to an infinite bus through a reactive tie line reaches its steady state stability limit. What is the power angle of the generator relative to the infinite bus voltage reference

1. Greater than 90 degrees
2. Equal to 90 degrees
3. Less than 90 degrees
4. Zero

176. A three phase 50 Hz, 11 kV and 37.5 MW at 0.9 p.f. capacity synchronous generator has its stator core diameter of 765 cm and an axial core length of 80 cm. For which power plant this generator is suitable?

1. Thermal coal fired plant
2. Hydroelectric power plant
3. Nuclear power plant
4. Pumped storage power plant

177. The stator of a 3-phase, 6-pole a.c. machine has 45 slots. The stator winding has 45 coils with a coil span of 6 slots. What type of winding will be selected for this machine?

1. Double-layer, fractional slot, short-pitched winding
2. Single-layer, fractional slot, short-pitched winding
3. Single-layer, integral slot, full-pitch winding
4. Double-layer, fractional slot, full-pitch winding

178. If the excitation of a 3-phase alternator operating on infinite bus bars is changed, which one of the following shall alter?

1. Active power of machine
2. Reactive power of machine
3. Terminal voltage of machine
4. Frequency of machine

179. Which of the following conditions are to be satisfied for proper synchronization of alternators?

1. Equal terminal voltage
2. Same frequency
3. Same phase sequence
4. Same kVA rating
5. Same phase displacement

Select the correct answer using the code given below:

1. i, iii and iv
2. i, ii, iv and v
3. ii, iii, iv and v
4. i, ii, iii and v

180. Which one of the following is the correct statement?

1. The armature current upon symmetrical 3-phase short circuit of a synchronous machine (armature resistance is negligible) constitutes q-axis current only.
2. The armature current upon symmetrical 3-phase short circuit of a synchronous machine (armature resistance is negligible) constitutes d-axis current only.
3. The armature current upon symmetrical 3-phase short circuit of a synchronous machine (armature resistance is negligible) has both d-axis and q-axis current only
4. Short circuit current can be divided into d-axis and q-axis components.