Electrical Machines A 3- phase synchronous motor can operate over a wide range of power factors i.e. from lagging to leading power factor. This is achieved by changing the field excitation. varying the applied voltage. varying the speed. changing the load. changing the field excitation. varying the applied voltage. varying the speed. changing the load. 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 2, 3 and 4 1, 2, and 3 1 and 3 1, 2 and 4 2, 3 and 4 1, 2, and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 240 V DC series motor takes 40 A when giving its rated output at 1500 rpm. Its resistance is 0.3 ohms. The value of resistance which must be added to obtain rated torque at 1000 rpm is 6 ohms. 1.9 ohms. 2.2 ohms. 5.7 ohms. 6 ohms. 1.9 ohms. 2.2 ohms. 5.7 ohms. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a DC Shunt Motor if the load current increases keeping the terminal voltage constant, then flux will increase. remain constant. any of the above. decrease. increase. remain constant. any of the above. decrease. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For P pole machine relation between electrical degrees and mechanical degrees is θelec = 4/P*θmech θelec = 2/P*θmech θelec = θmech θelec = P/2*θmech θelec = 4/P*θmech θelec = 2/P*θmech θelec = θmech θelec = P/2*θmech ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Open circuit in a transformer is prefered with high frequency supply rated transformer voltage rated transformer current direct current high frequency supply rated transformer voltage rated transformer current direct current ANSWER DOWNLOAD EXAMIANS APP
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