Alternator Multiple Choice Questions and Answers

36. It is never advisable to connect a stationary alternator to live bus-bars because it

   A.Is likely to run as synchronous motor

   B.Will get short-circuited

   C.Will decrease bus-bar voltage through momentarily

   D.Will disturb generated e.m.fs of other alternators connected in parallel

37. Under no-load condition, power drawn by the prime mover of an alternator goes to

   A.Produce induced e.m.f. armature winding

   B.Meet no-load losses

   C.Produce power in the armature

   D.Meet Cu losses both in armature and rotor windings

38. For proper parallel operation, a.c. polyphase alternators must have the same

   A.Speed

   B.Voltage rating

   C.kVA rating

   D.Excitation

39. Of the following conditions, the one which does not have to be met by alternators working in parallel is

   A.Terminal voltage of each machine must be the same

   B.The machines must have the same phase rotation

   C.The machines must operate at the same frequency

   D.The machines must have equal things

40. Three-phase alternators are invariably Y-connected because

   A.Magnetic losses are minimised

   B.Less turns of wire are required

   C.Smaller conductors can be used

   D.Higher terminal voltage is obtained

41. The main disadvantage of using short-pitch winding in alternators is that it

   A.Reduces harmonics in the generated voltage

   B.Reduces the total voltage around the armature coils

   C.Produces asymmetry in the three phase windings

   D.Increases Cu of end connections

42. At lagging loads, armature reaction in an alternator is

   A.Cross-magnetising

   B.Demagnetising

   C.Non-effective

   D.Magnetising

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