Electrical Machines The armature reaction mmf in a DC machines has a form of triangular. trapezoidal. rectangular. sinusoidal. triangular. trapezoidal. rectangular. sinusoidal. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A voltmeter gives 120 oscillations per minute when connected to the rotor of an induction motor. The frequency is 50Hz. The slip of the motor is 5% 25% 4% 2% 5% 25% 4% 2% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Voltage across the open circuited field termninals of a synchorous machine under slip test is DC. A modulated supply frequency AC voltage with slip frequency envelop. AC of supply frequency. DC of slip frequency. DC. A modulated supply frequency AC voltage with slip frequency envelop. AC of supply frequency. DC of slip frequency. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following factors improve commutation in a dc machine ? 1. High contact resistance of brushes 2. High inductance of the coils undergoing commutation 3. Shifting of brushes in the direction of rotation for a generator and in the opposite direction For a motor 4. Narrow width for the commutation bars Select the correct answer using the codes given below : Codes : 1 and 3 1, 2 and 4 1, 2, and 3 2, 3 and 4 1 and 3 1, 2 and 4 1, 2, and 3 2, 3 and 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The power factor of an induction motor operating at no load will have a value around 0.9 lag 0.2 lead unity 0.2 lag 0.9 lag 0.2 lead unity 0.2 lag 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 Rf maximum and Ra minimum Ra minimum and Rf minimum Ra maximum and Rf maximum Ra maximum and Rf minimum Rf maximum and Ra minimum Ra minimum and Rf minimum Ra maximum and Rf maximum ANSWER DOWNLOAD EXAMIANS APP
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