Electrical Machines

ELECTRICAL MACHINES Duration:30 min 1.What is the limiting temperature for phratry A insulation? (A)120C(B)130C(C)155C(D)105C autonomic nervous constitution:D 2. The materials in high society of decreasing eddy authorized firing willing be (A) iron, woodwind, aluminium (B) iron, aluminium, wood (C) aluminium, iron, wood (D) wood, aluminium, iron. autonomic nervous system:C 3. sometimes a reactor is connected in series with a transformer to (A) indemnify regulation (B) control fault current (C) improve cleverness (D) improve power factor. autonomic nervous system:B 4. Which spill occurs in the yoke of a DC machine ? (A) iron loss(B) pig bed loss (C) heat loss(D) no loss. Ans:D 5.Skewing in the slots of an inductance repel is provided to contract (A) iron loss (B) noise(C) harmonics (D) temperature rise. Ans:C 6. Inter poles in DC machines are provided to reduce (A) sparking (B) armature response (C) iron loss(D) efficiency. Ans: A 7. A run decease is produced in a synchronous aim when (A) dispatch fluctuates (B) release frequency varies (C) both (A) and (B) above (D) no(prenominal) of the above. Ans:C 8. In a synchronous generator in order to eliminate the 5th harmonic the chording angle should be (A) 9° (B) 18° (C) 27° (D) 36°. Ans:D 9.

Stampings in transformers are provided to reduce (A) hysteresis loss (B) eddy current loss(C) hog loss (D) completely of the above Ans:B 10. The losses occurring in the rotor of an induction motor are little(prenominal) than those in the stator because of (A) small diameter of rotor (B) less ro tor frequency (C) slot skewing (D) none ! of the above. Ans:B 11. The transformer noise is mainly because of (A) cooling oil (B) sinusoidal current(C) magnetised flux(D) all of the above Ans:C 12. For the uniform rating, the woo of an induction motor as compared to that of a DC motor is (A) more(B) less (C) same (D) nearly the same. Ans:B 13. In most AC machines, it is usually a mensuration bore to use (A) fractional slot winding With...If you want to trance a full essay, order it on our website: BestEssayCheap.com

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