Electrical Machines
A 3 - Φ, 6 pole, 50 Hz IM is running at a full load speed of 980 rpm. If it delivers an air gap power of 98000 Watt, calculate the rotor ohmic loss?

  1960 Watt.
 1800 Watt.
  980 Watt.
 1920 Watt.

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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 armature circuit.
 Any of above.
 Inserting an additional resistance in the field circuit.

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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, 2, and 3
 2, 3 and 4
 1 and 3

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Electrical Machines
The result of slip test on a 3-phase, 20 KVA, 400 V, 50 Hz connected salient pole alternator is given below- Phase value: Vmax = 100 V, Vmin = 96 V, Imax = 10 A and I min = 7 A. The direct and quadranature axis reactances are respectively

 8.248 and 5.54 Ω.
  14.28 and 5.54 Ω.
 8.248 and 9.60 Ω.
 14.28 and 9.60 Ω.

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