Electrical Machines Dc Machine Mmf Flux Density Online Exam Quiz
Electrical Machines Dc Machine Mmf Flux Density GK Quiz. Question and Answers related to Electrical Machines Dc Machine Mmf Flux Density. MCQ (Multiple Choice Questions with answers about Electrical Machines Dc Machine Mmf Flux Density
A 100KW, 250 V, 400 A, a long shunt compound generator has an armature resistance of 0.025 ohms. There are 1000 shunt fields turns per pole and 3 series field turns per pole. The series field is connected in a such a fashion that positive armature current produces direct-axis MMF which adds to that of the shunt field. Compute the gross MMF at the rated terminal current when shunt field current is 4.7A and speed is 1150 rpm.
Options
A : 5.9AT
B : 3.5AT
C : 4.7AT
D : 1.2AT
Which method needed to limit cross-magnetizing effect?
Options
A : by increasing reluctance of cross flux path
B : by chamfering the pole faces
C : by compensating winding
D : any of the mentioned
The armature mmf affects __________
Options
A : commutation
B : generated voltage
C : torque
D : any of the mentioned
The air-gap flux density waveform has decreased flux under one pole tip and measured under the other is due to __________
Options
A : cross magnetization
B : magnetization
C : demagnetization
D : saturation of iron magnetic circuit
Armature reaction in a dc machine is __________
Options
A : cross magnetizing in nature
B : magnetizing in nature
C : demagnetizing in nature
D : none of the mentioned
The flux distortion caused by cross magnetizing armature reaction is more pronounced in a __________
Options
A : dc shunt motor
B : dc series motor
C : any of the mentioned
D : differential Compound Motors
The brushes of a dc motor, are shifted by 5?, from the main field axis, then __________
Options
A : demagnetizing or magnetizing effect may occur depending on machine
B : cross-magnetization will be pronounced
C : both cross-magnetization as well as magnetization and demagnetization will occur
D : none of the mentioned
A dc shunt motor is running at 1000 rpm at the rated load torque. If we reverse the filed winding terminals, then the __________
Options
A : direction of rotation reverses and commutation will be unaffected
B : direction of rotation will be same and commutation will be unaffected
C : direction of ration reverses and commutation will be affected
D : direction of ration will be same and commutation will be affected
A dc shunt motor is running at 1000 rpm at the rated load torque. If we reverse the supply terminals, then the __________
Options
A : direction of rotation reverses and commutation will be unaffected
B : direction of rotation will be same and commutation will be unaffected
C : direction of ration reverses and commutation will be affected
D : direction of ration will be same and commutation will be affected
Compensating winding has an advantage of __________
Options
A : eliminating flux distortion
B : importing speed of response
C : protecting overloading
D : any of the mentioned
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