Electrical Machines The demagnetising component of armature reaction in a DC generator reduces inter poles flux density. increases armature speed. reduces generator emf. results in sparking trouble. reduces inter poles flux density. increases armature speed. reduces generator emf. results in sparking trouble. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 3 - Φ induction motor draws an current of 50 A from mains when starts by direct switching. If an auto transformer with 60 % tapping is used for starting the current drawn from the mains will be 50. 36. 80. 18. 50. 36. 80. 18. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a transformer which of the following losses are zero? All of these Rotational loss Copper loss Iron loss All of these Rotational loss Copper loss Iron loss ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements regarding dc machines : 1. possible resistance of shunt-field winding is 1 Ω 2. possible resistance of series-field winding is 1 Ω 3. electrographite brushes are used for 230 V, 10 A machines 4. Copper-graphite brushes are used for 230 V, 10 A machines 5. Possible armature-circuit resistance is 1 Ω From these, the correct statements are 1, 4 1, 3, 5 2, 3 , 5 2, 4 ,5 1, 4 1, 3, 5 2, 3 , 5 2, 4 ,5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc shunt motor has external resistance Ra and Rf in the armature and field circuits respectively. Armature current at starting can be reduced by keeping Ra maximum and Rf minimum Ra minimum and Rf minimum Rf maximum and Ra minimum Ra maximum and Rf maximum Ra maximum and Rf minimum Ra minimum and Rf minimum Rf maximum and Ra minimum Ra maximum and Rf maximum ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc shunt motor runs at a no-load speed of 1140 rpm. At full load, armature reaction weakens the main flux by 5% whereas the armature circuit voltage drops by 10%. The motor full-load speed in rpm is 1203 1080 1000 1200 1203 1080 1000 1200 ANSWER DOWNLOAD EXAMIANS APP
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