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
 1, 2 and 5
 1 and 4
 3 and 5

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Electrical Machines
A dc shunt generator, when commissioned after a major repair of the field system, failed to build Up voltage. It was because

 field resistance was higher than critical resistance
 field winding was wrongly connected
 there was a break in the armature circuit
 field system lost residual magnetism

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