Electrical Machines What is the emf generated by a 4 pole Lap connected DC Motor rotating at 1500 rpm having 1000 conductors and useful flux per pole is 0.4 mWb. 30 volts. 10 volts. 20 volts. 40 volts. 30 volts. 10 volts. 20 volts. 40 volts. 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 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 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A commutator in dc machine provide ----------------- rectification? half wave controlled full wave half wave full wave controlled half wave controlled full wave half wave full wave controlled ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The functions of inter poles are nullify reactance voltage and improve the commutation. both 1 and 2 reduce cross magnetization effect and improve commutation None of these nullify reactance voltage and improve the commutation. both 1 and 2 reduce cross magnetization effect and improve commutation None of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 2 KVA transformer has iron loss of 150 W and full load copper loss of 250 W. The maximum efficiency of the transformer would occur when the total loss is 300 W 500 W 400W 250 W 300 W 500 W 400W 250 W ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements regarding the speed control of dc motors : 1. ward-leonard method is suitable forconstant-torque drives 2. Ward-leonard method is suitable for constant-power drives 3. field-control method facilitates speed control below base speed 4. Armature-resistance control method is more efficient than ward-leanard method 5. Field-control method is suitable for constant-torque drives 6. Armature-resistance control method is suitable for constant-torque drives From these, the correct answer is 1, 2, 6 1, 3, 5 1, 2, 5 1, 4, 6 1, 2, 6 1, 3, 5 1, 2, 5 1, 4, 6 ANSWER DOWNLOAD EXAMIANS APP
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