Electrical Machines In a transformer operating at constant voltage if the input frequency increases, the core loss remains constant. decrease. increase. None of these remains constant. decrease. increase. None of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Direct-on-line (DOL) starters are not suitable for starting large DC motors, because the starting current will be enormously high. the motor may run away. the starting torque becomes low. the motor may not start. the starting current will be enormously high. the motor may run away. the starting torque becomes low. the motor may not start. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Short circuiting is caused in the armature winding due to failure of insulation between two turns of coil. any of above. failure of insulation between two commutator bars. grounding of two or more turns of the same coil. failure of insulation between two turns of coil. any of above. failure of insulation between two commutator bars. grounding of two or more turns of the same coil. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements : Interpoles in dc machines 1. reducearmature reaction effects in the interpolar region 2. have the same dimension as main polls 3. have their windings connected in series with the armature 4. have same number of turns as the armature 5. have the polarity same as that of the main pole ahead in a motor From these, the correct statements are 1, 3 and 5 1, 2 and 3 1, 2, 3 and 5 1 and 3 1, 3 and 5 1, 2 and 3 1, 2, 3 and 5 1 and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Neglecting all losses, the developed torque (T) of DC separately excited motor, operating under constant terminal voltage is reduced to its output power (P) as T2 ∝ P3. T ∝ P. T is independent of P. T ∝ √P. T2 ∝ P3. T ∝ P. T is independent of P. T ∝ √P. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a dc generator operating on load with its brushes on the geometrical neutral axis (GNA), the magnetic neutral axis (MNA) is shifted in the direction of rotation. Now, if the brushes are given a lead of 90° (electrical), then the MNA will coincide with the GNA shift forward by less than 90° shift forward by 90° shift forward by more than 90° coincide with the GNA shift forward by less than 90° shift forward by 90° shift forward by more than 90° ANSWER DOWNLOAD EXAMIANS APP
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