Electrical Machines The armature reaction mmf in a DC machines has a form of triangular. sinusoidal. trapezoidal. rectangular. triangular. sinusoidal. trapezoidal. rectangular. 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 2, 3 and 4 1, 2 and 4 1, 2, and 3 1 and 3 2, 3 and 4 1, 2 and 4 1, 2, and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For a specific open-circuit voltage of a DC generator, the short-circuit electric current will be maximum when it is separately excited. cumulatively compounded. shunt connected. differentially compounded. separately excited. cumulatively compounded. shunt connected. differentially compounded. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A smaller air gap in a polyphase induction motor helps to reduce the chance of crawling. reduce the chance of cogging. increase the starting torque. reduce the magnetizing current. reduce the chance of crawling. reduce the chance of cogging. increase the starting torque. reduce the magnetizing current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Find the synchronous reactance of alternators in which a given field current of 200 A on short circuit and a generated emf of 50 V on open circuit. Armature resistance is 0.1 ohm 0.25Ω. 0.23Ω. 1Ω. 0.5Ω. 0.25Ω. 0.23Ω. 1Ω. 0.5Ω. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For small value armature current Ia the torque developed by a DC series motor is proportional to √Ia. 1/Ia. Ia. Ia2. √Ia. 1/Ia. Ia. Ia2. ANSWER DOWNLOAD EXAMIANS APP
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