Electrical Machines If the applied voltage to a dc machine is 230 V, then the back emf, for maximum power developed, is 230 V 460 V 200 V 115 V 230 V 460 V 200 V 115 V ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following methods are used to control the speed of DC motors is supply voltage control armature circuit resistance control field current control All of these supply voltage control armature circuit resistance control field current control All of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The magnetic circuit of a dc shunt generator with negligible armature resistance and brush contact voltage drop remains unsaturated when it delivers full-load current at rated terminal voltage. The brushes are kept in the interpolar axis and speed is maintained constant. When the load is switched off, the terminal voltage would decrease increase become zero remain the same decrease increase become zero remain the same 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, 5 1, 3, 5 1, 2, 6 1, 4, 6 1, 2, 5 1, 3, 5 1, 2, 6 1, 4, 6 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines An induction motor having 8 poles runs at 727.5 rpm. If the supply frequency is 50Hz, the emf in the rotor will have a frequency of 51.5Hz 2.5Hz 48.5Hz 1.5Hz 51.5Hz 2.5Hz 48.5Hz 1.5Hz ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The heat transfer by convection in a transformer least depends on color of the paint. air velocity. surface area. temperature difference. color of the paint. air velocity. surface area. temperature difference. ANSWER DOWNLOAD EXAMIANS APP
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