Electrical Machines Dc Motor Starting Online Exam Quiz
Electrical Machines Dc Motor Starting GK Quiz. Question and Answers related to Electrical Machines Dc Motor Starting. MCQ (Multiple Choice Questions with answers about Electrical Machines Dc Motor Starting
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 _________
Options
A : 0.382 ms
B : 0.456 ms
C : 0.573 ms
D : 0.312 ms
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.
Options
A : 2.788
B : 3.038
C : 2.688
D : 2.588
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?
Options
A : 3
B : 2
C : 4
D : 5
The shunt motor starters that can be used is/are ___________
Options
A : 3-point and 4-point starter
B : 5-point starter
C : 4-point starter
D : 5-point and 3-point starter
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 _________
Options
A : incorrect brush placement
B : incorrect pole and core alignment
C : incorrect field supply
D : all of the mentioned
The effect of fringing increases as we _________
Options
A : increase air gap
B : decrease air gap
C : increase in flux density
D : introduce more ferric core material
A starting resistance is inserted at the starting in an induction motor as well as dc motor.
Options
A : Induction motor has to control starting torque whereas in dc motor, it is done to avoid large current
B : To limit starting current in both the machines
C : To limit starting speed
D : All of the mentioned
Thyristor controlled starter is preferred over DOL starter due to _________
Options
A : lesser losses
B : controlled direction
C : least resistance offered
D : all of the mentioned
The post effects of the armature reaction is _________
Options
A : main field distortion
B : shift in MNA
C : reduction in main field
D : none of the mentioned
If the students give a forward shift of 10° to the dc generator, then it _________
Options
A : reduces flux per pole
B : improves flux per pole
C : increases the flux density in core
D : none of the mentioned
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