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 varying the speed. changing the field excitation. changing the load. varying the applied voltage. varying the speed. changing the field excitation. changing the load. varying the applied voltage. 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 3 2, 3 and 4 1, 2 and 4 1 and 3 1, 2, and 3 2, 3 and 4 1, 2 and 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Hysteresis loss will depends on f1.6 f² f³ f f1.6 f² f³ f ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following will vary the maximum torque? rotor resistance R rotor reactance X both 1 and 2 None of these rotor resistance R rotor reactance X both 1 and 2 None of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If field current is decreased in shunt dc motor, the speed of the motor None of these decreases. remains same. increases. None of these decreases. remains same. increases. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 Ω and armature current is 10 A. of the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be 2 .1 Ω 3.1 Ω 1.8 9 Ω 1.79 Ω 2 .1 Ω 3.1 Ω 1.8 9 Ω 1.79 Ω ANSWER DOWNLOAD EXAMIANS APP
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