Bissoy.com
Doctors Medicines MCQs Q&A

How should be the value of field mmf to prevent excessive distortion of field form by armature reaction in an electric machine?

How should be the value of field mmf to prevent excessive distortion of field form by armature reaction in an electric machine? Correct Answer large compared to armature mmf

The field mmf must be large compared to armature mmf to prevent excessive distortion of field form by armature reaction. The air gap length can be made large to reduce the distortion effect of armature reaction as a long air gap needs a large field mmf.

Related Questions

In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made
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.
Consider the following statements with respect to synchronous machines. State whether these statements are true or false. (a) Armature reaction is demagnetising when a generating machine supplies zero power factor lagging current. (b) Armature reaction is magnetising when a generating machine supplies zero power factor leading current. (c) Armature reaction is mostly cross-magnetising, though it has a small demagnetising component, when a generating machine supplies unity power factor current.
How should the field mmf be with respect to armature mmf to reduce the armature reaction?
Consider the following statements: The armature reaction mmf in a dc machine is: 1. Stationery with respect to the field 2. Rotating with respect to the field poles 3. Rotating with respect to the armature Which of these statements are correct?
The armature reaction in a DC machine causes distortion in the main field flux. Effect of armature reaction can be reduced by_________
What should be the range of the field mmf to armature mmf ratio at full load?
Interpoles provide mmf more than armature mmf in a dc machine.
In an alternator, the armature winding is kept stationary while the field winding is kept rotating for the following reasons: 1. Armature handles very large current and high voltage 2. Armature fabrication, involving deep slots to accommodate large coils, is easy if armature is kept stationary 3. It is easier to cool the stator than the rotor Which of the above reasons are correct?
In a DC machine, z, p, Ia and a are respectively the number of conductors, number of poles, armature current and number of parallel paths. The peak value of fundamental component of armature MMF wave is ____________ b) 8/Π2 c) 4/Π d) 8/Π2