Electrical Machines
In which of the following speed control of DC motor the speed obtained is below than the rated speed?

 Any of above.
 Armature voltage control.
 Field resistance control.
 Armature circuit resistance control.

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Electrical Machines
Consider the following statements regarding the magnetization characteristics of a dc generator : 1. It represents the variation of field flux with field current. 2. Variation of open-circuit terminal voltage with field current is independent of speed 3. It is non-linear from zero to rated field current 4. It helps to determine the critical field resistance at a given speed 5. It always starts from the origin Which of these statements are correct ?

 2, 3 and 4
 3 and 5
 1 and 4
 1, 2 and 5

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Electrical Machines
The following statements relate to compensating winding (CW) and interpole winding (IW) of a dc machine : 1. CW neutralizes the armature reaction under a pole pitch 2. IW is connected in series with armature circuit 3. IW produces mmf in the commutating zone only 4. CWmmf is directed along the brush axis 5. Mmf produced by IW is equal to armature mmf From these, the correct statements are

 2, 3, 4, 5
 1, 3, 4, 5
 2, 3, 4
 1, 2, 3, 4 and 5

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