Electrical Drives And Controls Set 12

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 12

Q1 | Thyristor controlled starter is preferred over DOL starter due to                    
Q2 | For a 7.46 kW, 200 V dc shunt motor with full load efficiency of 85% has armature resistance of 0.25 ohms. Calculate the value of starting resistance in ohms for a current 1.5 times of the full load current.
Q3 | The effect of fringing increases as we
Q4 | The post effects of the armature reaction is                    
Q5 | If the students give a forward shift of 10° to the dc generator, then it                    
Q6 | A dc machine is run at rated speed in forward direction and then in backward direction. It is observed that, speeds of the rotation are different, then it leads to the conclusion of                    
Q7 | For a dc machine, its commutator has a diameter of 50 c rotating at 1000 rpm. For a brush width of 1 cm, the time commutation taken by the machine will be                    
Q8 | An induction motor can be said analogous to                    
Q9 | A 3-phase induction motor with its rotor blocked behaves similar to a                    
Q10 | No load current in induction motor is 10- 20% of full load current and the no load current of transformer is 2-6%.
Q11 | The no load current of the transformer is very less due to                    
Q12 | The no load current of the induction motor is high due to                    
Q13 | At no load induction motor has possible power factor as                    
Q14 | Mechanically air gaps in induction motor are kept very low to avoid                    
Q15 | The low no load power factor                    
Q16 | An induction motor when started on load, it does not accelerate up to full speed but runs at 1/7th of the rated speed. The motor is said to be                    
Q17 | The great advantage of the double squirrel-cage induction motor over single cage rotor is that its                    
Q18 | Ward-Leonard system of system of speed control is not recommended for                    
Q19 | Mark the wrong option. Which of the following cause and effect behaviour in speed control is correct when field resistance is increased.
Q20 | At a very low speed, increase in field resistance will                    
Q21 | Small DC motors have best speed control by                    
Q22 | To implement armature voltage control, it must be ensured that                    
Q23 | The torque limit of speed for a shunt motor                    
Q24 | A laboratory group was working with a set of 3-hp shunt DC motor. But there was a mistake that it was fused with a 0.3A fuse instead 3A fuse. Then it was started
Q25 | Run-away for large DC machine is avoided by using                    
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