Industrial Drivers

51. Ward-Leonard controlled D.C. drives are generally used for _________ excavators.

1. Light duty
2. Medium duty
3. Heavy duty
4. All of the above

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52. When the load is above _________ a synchronous motor is found to be more economical.

1. 2 kW
2. 20 kW
3. 50 kW
4. 100 kW

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53. Which feature, while selecting a.motor for centrifugal pump, will be of least significance?

1. Starting characteristics
2. Operating speed
3. Horse power
4. Speed control

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54. Which of the following alternatives will be cheaper?

1. A 100 H.P. AC. three phase motor
2. Four motors of 25 H.P. each
3. Five motors of 20 H.P. each
4. Ten motors of 10 H.P. each

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55. Which of the following happens when star-delta starter is used?

1. Starting voltage is reduced
2. Starting current is reduced
3. Both (a) and (b)
4. None of the above

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56. Which of the following is essentially needed while selecting a motor?

1. Pulley
2. Starter
3. Foundation pedal
4. Bearings

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57. Which of the following machines has heavy fluctuation of load?

1. Printing machine
2. Punching machine
3. Planer
4. Lathe

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58. Which of the following motors are best for the rolling mills?

1. Single phase motors
2. Squirrel cage induction motors
3. Slip ring induction motors
4. D.C. motors

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59. Which of the following motors are pre-ferred for overhead travelling cranes?

1. Slow speed motors
2. Continuous duty motors
3. Short time rated motors
4. None of the above

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60. Which of the following motors has series characteristics?

1. Shaded pole motor
2. Repulsion motor
3. Capacitor start motor
4. None of the above

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