Which of the following methods is used for air cooling of turbo-alternators ?
(A) One sided axial ventilation
(B) Two sided axial ventilation
(C) Multiple inlet system
(D) All of the above
The slot leakage can be calculated by making which of the following assumptions ?
(A) The current in the slot conductors is uniformly distributed over their cross-section
(B) The leakage path is straight across the slot and around the iron at the bottom
(C) The permanence of air paths is only considere
(D) The reluctance of iron paths is assumed as zero
Which of the following methods does not take into account the maximum temperature rise under variable load conditions ?
(A) Equivalent power method
(B) Equivalent current method
(C) Method of average losses
(D) Equivalent torque method
With direct water cooling it is possible to have ratings of about_____________?
(A) 200 MW
(B) 300 MW
(C) 400 MW
(D) 600 MW
In self cooled motors the cooling time constant is about ___________ than the heating time constant because cooling conditions are worse at standstill?
(A) 2 to 3 times greater
(B) 3 to 4 times greater
(C) 4 to 5 times greater
(D) none of the above
Direct water cooling of rotor winding presents_____________?
(A) no mechanical difficulties
(B) lesser mechanical difficulties
(C) greater mechanical difficulties
(D) none of the above
The distance between the starts of two consecutive coils measured in terms of coil sides is called_____________?
(A) front pitch
(B) winding pitch
(C) commutator pitch
(D) back pitch
Power transformers should be designed to have maximum efficiency________________?
(A) at one-fourth load
(B) at one-half load
(C) at or near full load
(D) any of the above
Yokes with rectangular cross-section are used for_______________?
(A) small capacity transformers
(B) medium capacity transformers
(C) large capacity transformers
(D) any of the above
Which of the following methods is most accurate ?
(A) Equivalent current method
(B) Equivalent power method
(C) Equivalent torque method
(D) Method of average losses