Electrical Machines A commutator with a diameter of 50 cm rotating at 1000 rpm. For a brush width of 1.5 cm, find the time of commutation in ms. 0.573. 0.649. 0.443. 0.512. 0.573. 0.649. 0.443. 0.512. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following machine is invariably provided with forced ventilation? Fractional horse power slow speed motor. Fractional horse power high speed motor. 50 MW generator in a power plant. Hermetically sealed motor of refrigerator. Fractional horse power slow speed motor. Fractional horse power high speed motor. 50 MW generator in a power plant. Hermetically sealed motor of refrigerator. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If an AC servomotor has one of its winding excited by AC, then voltage measured at the other winding with rotor running will be proportional to rotor speed. proportional to square of rotor speed. constant independent of speed. zero. proportional to rotor speed. proportional to square of rotor speed. constant independent of speed. zero. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In DC series motor the speed is ______________ proportional to the armature current. directly. none of these. inversely. has no relation. directly. none of these. inversely. has no relation. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If starter is not used with large DC motor for starting, it will damage the armature and commutator. draw a starting current many times its rated full load current. all of above. provide execessive voltage drop in line. damage the armature and commutator. draw a starting current many times its rated full load current. all of above. provide execessive voltage drop in line. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is the frequency of a alternator, if P = number of poles and N = revolution made per second? 120 / PN Hz. 120N / P Hz. 120P / N Hz. PN / 2 Hz. 120 / PN Hz. 120N / P Hz. 120P / N Hz. PN / 2 Hz. ANSWER DOWNLOAD EXAMIANS APP
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