Electrical Machines Flashing of DC generator means increasing flux density by providing extra ampere-turns in field. neutralization of residual magnetism. creation of residual magnetism by a DC source. None of these increasing flux density by providing extra ampere-turns in field. neutralization of residual magnetism. creation of residual magnetism by a DC source. None of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In Ward-Leonard method of speed control, the direction of rotation of motor is reversed usually reversing the connection of the generator armature terminal. generator field terminal. motor armature terminal. motor field terminal. generator armature terminal. generator field terminal. motor armature terminal. motor field terminal. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Air core transformer as compared to iron core transformer, has no magnetic core loss. less magnetic core loss. more magnetic core loss. more copper loss. no magnetic core loss. less magnetic core loss. more magnetic core loss. more copper loss. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%. 82.5% 78.5% 72.5% 67.5% 82.5% 78.5% 72.5% 67.5% 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 minimum and Rf minimum Ra maximum and Rf maximum Rf maximum and Ra minimum Ra maximum and Rf minimum Ra minimum and Rf minimum Ra maximum and Rf maximum Rf maximum and Ra minimum Ra maximum and Rf minimum ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A commutator with a diameter of 50 cm rotating at 1000 rpm. For a brush width of 1.5 cm, find the time of commutation in ms. 0.573. 0.512. 0.649. 0.443. 0.573. 0.512. 0.649. 0.443. ANSWER DOWNLOAD EXAMIANS APP
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