Electrical Machines A 4-pole dc generator runs at 1500 rpm. The frequencyof current in the armature winding is 0 Hz 100 Hz 25 Hz 50 Hz 0 Hz 100 Hz 25 Hz 50 Hz ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is/are the necessary conditions for voltage build up in self excited generator? Poles should contain residual flux. Field winding resistance should be less than critical resistance. All of these Field winding should be properly connected to armature winding. Poles should contain residual flux. Field winding resistance should be less than critical resistance. All of these Field winding should be properly connected to armature winding. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of following winding is connected in series with armature winding of DC machine? Compensating winding. Both Compensating and Commutating pole winding. Commutating pole winding. Auxiliary winding. Compensating winding. Both Compensating and Commutating pole winding. Commutating pole winding. Auxiliary winding. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Minimum allowable resistivity of power transformer insulating oil is generally taken as 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 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%. 78.5% 72.5% 67.5% 82.5% 78.5% 72.5% 67.5% 82.5% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following will vary the maximum torque? rotor resistance R None of these both 1 and 2 rotor reactance X rotor resistance R None of these both 1 and 2 rotor reactance X ANSWER DOWNLOAD EXAMIANS APP
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