Electrical Machines The armature of DC machine is made of silicon steel lamination to increase the permeability. reduce both eddy current and hysteresis loss. reduce hysteresis loss only. reduce eddy current loss only. increase the permeability. reduce both eddy current and hysteresis loss. reduce hysteresis loss only. reduce eddy current loss only. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Sparkless commutation can be achieved by employing high resistance carbon brushes. compensating winding. any one or more of the above methods. inter poles. high resistance carbon brushes. compensating winding. any one or more of the above methods. inter poles. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The slip of an induction motor during DC rheostatic braking is 2 + s. 2 - s. 1 - s. s. 2 + s. 2 - s. 1 - s. s. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If the no-voltage release in a DC motor starter fails to operate on failure of supply, on resumption of supply the motor will develop very low starting torque. start automatically without trouble. not start automatically. get damaged. develop very low starting torque. start automatically without trouble. not start automatically. get damaged. 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 : 2, 3 and 4 1, 2 and 4 1, 2, and 3 1 and 3 2, 3 and 4 1, 2 and 4 1, 2, and 3 1 and 3 ANSWER DOWNLOAD EXAMIANS APP
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 9.60 Ω. 14.28 and 5.54 Ω. 8.248 and 9.60 Ω. 8.248 and 5.54 Ω. 14.28 and 9.60 Ω. 14.28 and 5.54 Ω. 8.248 and 9.60 Ω. ANSWER DOWNLOAD EXAMIANS APP
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