31. ………………….. method of starting a three phase induction motor needs six terminals.
(a) Star-delta
(b) Resistance starting
(c) Auto-transformer
(d) None of the above
32. In ………………… method of starting three phase induction motors, the starting voltage is not reduced.
(a) auto-transformer
(b) star-delta
(c) slip ring
(d) any of the above
33. In jaw crushers, a motor has too often started against ………………. load.
(a) heavy
(b) medium
(c) normal
(d) low
34. For a motor-generator set which of the following motors will be preferred?
(a) Synchronous motor
(b) Slip ring induction motor
(c) Pole changing induction motor
(d) Squirrel cage induction motor
35. Which of the following motors are usually preferred for kiln drives?
(a) Cascade controlled A.C. motor
(b) Slip ring induction motor
(c) Three phase shunt wound commutator motor
(d) Any of the above
36. Heat control switches are used in
(a) Transformers
(b) cooling ranges
(c) three phase induction motors
(d) single phase
37. …………………… has a relatively wider range of speed control.
(a) Synchronous motor
(b) Ship ring induction motor
(c) Squirrel cage induction motor
(d) D.C. shunt motor
38. In squirrel cage induction motors which of the following methods of starting cannot be used?
(a) Resistance in rotor circuit
(b) Resistance in stator circuit
(c) Auto-transformer starting
(d) Star-delta starting
39. In which of the following applications the load on motor changes in cyclic order?
(a) Electric shovels
(b) Cranes
(c) Rolling mills
(d) All of the above
40. Flame proof motors are used in
(a) paper mills
(b) steel mills
(c) moist atmospheres
(d) explosive atmospheres
41. Which of the following machines has a heavy fluctuation of load?
(a) Printing machine
(b) Punching machine
(c) Planer
(d) Lathe
42. For derries and winches which of the following drives can be used?
(a) Pole changing squirrel cage motors
(b) D.C. motors with Ward-Leonard control
(c) A.C. slip ring motors with variable resistance
(d) Any of the above
43. Battery operated scooter for braking uses
(a) plugging
(b) mechanical braking
(c) regenerative braking
(d) rheostatic braking
44. ………………… has least range of speed control.
(a) Slip ring induction motor
(b) Synchronous motor
(c) D.C. shunt motor
(d) Schrage motor
45. …………………… has the least value of starting torque to full load torque ratio.
(a) D.C. shunt motor
(b) D.C. series motor
(c) Squirrel cage induction motor
(d) Slip ring induction motor
