Electrical Machines What is/are the necessary conditions for voltage build up in self excited generator? Field winding should be properly connected to armature winding. Poles should contain residual flux. Field winding resistance should be less than critical resistance. All of these Field winding should be properly connected to armature winding. Poles should contain residual flux. Field winding resistance should be less than critical resistance. All of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In auto transformer if the turn ratio is K, what is the power transferred inductively? K × input power None of these both A and B (1-K) × input power K × input power None of these both A and B (1-K) × input power ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A self-excited shunt generator fails to build up, because 1. the field circuit is open 2. The armature circuit is open 3. the residual magnetism is absent 4. The direction of rotation is wrong From these, the correct answer is 1, 3 1, 2 and 3 3 only 1, 2, 3 and 4 1, 3 1, 2 and 3 3 only 1, 2, 3 and 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A transformer core is made up of a silicon steel laminations which has maximum flux density 1 Tesla. If it was cold rolled grain oriented its flux density increases to 1.6 Tesla. What is the saving in core size or area due to cold rolled grain oriented process? 40% 68% 60% 38% 40% 68% 60% 38% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Maximum allowable tan - delta (tanδ) of dielectric dispassion factor of power transformer insulating oil is generally taken as 3 at 90°C. 1 at 90°C. 0.5 at 90°C. 2 at 90°C. 3 at 90°C. 1 at 90°C. 0.5 at 90°C. 2 at 90°C. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In DC machine torque depends on which of the following? both A and B speed armature current (I) flux (φ) both A and B speed armature current (I) flux (φ) ANSWER DOWNLOAD EXAMIANS APP
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