Electrical Machines A dc shunt motor has external resistance Ra and Rf in the armature and field circuits respectively. Armature current at starting can be reduced by keeping Ra minimum and Rf minimum Ra maximum and Rf minimum Rf maximum and Ra minimum Ra maximum and Rf maximum Ra minimum and Rf minimum Ra maximum and Rf minimum Rf maximum and Ra minimum Ra maximum and Rf maximum ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following is done in speed control of DC motor by field flux control? Inserting resistance to armature circuit and field circuit. Inserting an additional resistance in the field circuit. Inserting an additional resistance in the armature circuit. Any of above. Inserting resistance to armature circuit and field circuit. Inserting an additional resistance in the field circuit. Inserting an additional resistance in the armature circuit. Any of above. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For very sensitive and wide speed control, the preferable control method is Field control. Ward-Leonard control. Multiple voltage control. Armature control. Field control. Ward-Leonard control. Multiple voltage control. Armature control. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 4-pole dc generator runs at 1500 rpm. The frequencyof current in the armature winding is 25 Hz 0 Hz 100 Hz 50 Hz 25 Hz 0 Hz 100 Hz 50 Hz ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The counter (or back) emf in a dc machine is 1. the same as generated emf in a dc motor 2. proportional to field flux and armature speed 3. not the same as generated emf in a dc motor 4.inversely proportional to field flux 5. proportional to number of armature conductors 6. constant from no load to full load From these, the correct answer is 3, 4, 5 1, 2, 5 2, 4, 5, 6 2, 3, 6 3, 4, 5 1, 2, 5 2, 4, 5, 6 2, 3, 6 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a DC machine, which of these parameters remain the same whether it runs as a DC motor or a DC generator? Induced emf. Mechanical power. Can not be determined. Armature current. Induced emf. Mechanical power. Can not be determined. Armature current. ANSWER DOWNLOAD EXAMIANS APP
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