Electrical Drives And Controls Set 11

Mechanical Engineering

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This set of Electrical Drives and Controls EDC Multiple Choice Questions & Answers (MCQs) focuses on Electrical Drives And Controls Set 11

Q1 | What is the form of the progressive windings?
  • double layer diamond coil windings
  • single layer diamond coil windings
  • multi layer diamond coil windings
  • three layer diamond coil windings
Answer: single layer diamond coil windings
Q2 | When is the skein winding made use of?
  • when small amount of relatively small size wire is used
  • when large amount of relatively small size wire is used
  • when large amount of relatively large size wire is used
  • when small amount of relatively large size wire is used
Answer: when small amount of relatively small size wire is used
Q3 | What kind of motor employs the skein winding made use of?
  • maximum horse power single phase induction motor
  • fractional horse power single phase induction motor
  • minimum horse power single phase induction motor
  • zero horse power single phase induction motor
Answer: fractional horse power single phase induction motor
Q4 | Which winding is mostly used winding in the single phase induction motor?
  • circular winding
  • concentric winding
  • progressive winding
  • skein winding
Answer: concentric winding
Q5 | What is/are the advantages of the skein winding?
  • low cost to wind
  • low cost to insert
  • permits some freedom of choice of distribution
  • low cost to wind, low cost to insert, permits some freedom of choice of distribution
Answer: low cost to wind, low cost to insert, permits some freedom of choice of distribution
Q6 | What material is used in the tunnel of the rotor of the single phase induction motor?
  • aluminium
  • copper
  • steel
  • wood
Answer: aluminium
Q7 | What type of operations are used in the starting switches?
  • mechanical operation
  • electrical operation
  • centrifugal operation and mechanical operation
  • centrifugal operation
Answer: centrifugal operation and mechanical operation
Q8 | The ac electrolytic capacitor is formed by winding two sheets of etched aluminium foil.
  • true
  • false
Answer: true
Q9 | The electrolytic capacitor and insulator unit is impregnated using ethylene glycol or a derivative.
  • true
  • false
Answer: true
Q10 | What is the range of the power factor of electrolytic capacitors?
  • 2-4
  • 4-6
  • 6-8
  • 7-9
Answer: 6-8
Q11 | Why starters are required in a DC motor?
  • back emf of these motors is zero initially
  • these motors are not self-starting
  • these motors have high starting torque
  • to restrict armature current as there is no back emf at starting
Answer: to restrict armature current as there is no back emf at starting
Q12 | For which motors DOL starter can be used?
  • up to 5 h.p
  • up to 10 h.p
  • up to 15 h.p
  • up to 20 h.p
Answer: up to 5 h.p
Q13 | A three-point starter is used for                    
  • shunt motors
  • shunt as well as compound motors
  • shunt, compound and series motors
  • not for dc motors
Answer: shunt as well as compound motors
Q14 | The starting resistance of a DC shunt motor is generally              
  • low
  • around 0.5 kΩ
  • around 5 kΩ
  • infinitely large
Answer: low
Q15 | What will happen if DC motor is used without starter?
  • heavy sparking at brushes
  • it’ll start smoothly
  • will not start at all
  • depends on load
Answer: heavy sparking at brushes
Q16 | Motor will start quickly when used without starter.
  • true
  • false
Answer: true
Q17 | In shunt and compound motor starting the shunt field should be made on with full starting resistance in                          
  • series with field
  • parallel with field
  • series with armature
  • parallel with armature
Answer: series with armature
Q18 | A starter is required for a 220-V shunt motor. The maximum allowable current is 55 A and the minimum current is about 35 A. The armature resistance of the motor is 0.4 Ω. What will be the number of sections of starter resistance required?
  • 5
  • 4
  • 6
  • 8
Answer: 6
Q19 | γ is given as 1.585. Resistance at maximum allowable current is given equal to 4 Ω, what is the 5th step resistance?
  • 0.235
  • 0.370
  • 1.476
  • 2
Answer: 0.235
Q20 | Four-point starter is used when
  • motor field current is varied in narrow range
  • motor speed is varied in small range
  • motor field current is varied over wide range
  • can be used anywhere
Answer: motor field current is varied over wide range
Q21 | A starting resistance is inserted at the starting in an induction motor as well as dc motor.
  • induction motor has to control starting torque whereas in dc motor, it is done to avoid large current
  • to limit starting current in both the machines
  • to limit starting speed
  • all of the mentioned
Answer: induction motor has to control starting torque whereas in dc motor, it is done to avoid large current
Q22 | A 100 hp, 250 V, 350 A shunt dc motor with an armature resistance of 0.05 ohms. To limit maximum starting current to twice the rated of its value, what will be the number of stages of starting resistances?
  • 3
  • 2
  • 4
  • 5
Answer: 3
Q23 | 2 TYPICAL CONTROL CIRCUITS FOR SHUNT AND SERIES MOTORS
  • starting resistance would burn
  • field winding would burn
  • speed will rise steeply
  • any of the mentioned
Answer: starting resistance would burn
Q24 | The shunt motor starters that can be used is/are                        
  • 3-point and 4-point starter
  • 5-point starter
  • 4-point starter
  • 5-point and 3-point starter
Answer: 3-point and 4-point starter
Q25 | The direct-on-line starter is used to start a small dc motor because it limits initial current drawn by armature circuit.
  • true
  • false
Answer: false
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