Electrical Machines What is the necessity of copper brushes in a dc motors? To convert alternating supply current to direct current. To absorb the mechanical shocks produced during running condition. To increase the flux cutting by the rotor. None of these. To convert alternating supply current to direct current. To absorb the mechanical shocks produced during running condition. To increase the flux cutting by the rotor. None of these. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For pure resistive load what is the armature reaction? All of these demagnetization magnetization cross magnetization All of these demagnetization magnetization cross magnetization ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The speed of a cumulatively compound DC motor can be controlled by varying Shunt field resistance control. Armature resistance control. Armature voltage control. Any of above. Shunt field resistance control. Armature resistance control. Armature voltage control. Any of above. 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, 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 1 and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In synchronous motor the torque is proportional to Power P 1/P 1/P² P² Power P 1/P 1/P² P² ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In double cage induction motor, the inner cage offers low resistance and high reactance. high resistance and low reactance. high resistance and high reactance. low resistance and low reactance. low resistance and high reactance. high resistance and low reactance. high resistance and high reactance. low resistance and low reactance. ANSWER DOWNLOAD EXAMIANS APP
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