Electrical Machines In a three phase star - delta transformer, what is the angle difference between primary and secondary phase voltages? Delta side lags by -30°. Delta side leads by 30°. Star side lags by -30°. Star side leads by 30°. Delta side lags by -30°. Delta side leads by 30°. Star side lags by -30°. Star side leads by 30°. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Copper brushes in DC machine are used in both of above cases. None of these where low voltage and high currents are involved. where high voltage and low current. in both of above cases. None of these where low voltage and high currents are involved. where high voltage and low current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Short circuit test is performed on a transformer with a certain impressed voltage at rated frequency. If the short circuit test is now performed with the same magnitude of impressed voltage, but at frequency higher than the rated frequency then The magnitude of circuit as well as the power factor will decrease. The magnitude of current will decrease but the power factor will increase. The magnetude of current will increase, but power factor will decrease. The magnitude will both increase. The magnitude of circuit as well as the power factor will decrease. The magnitude of current will decrease but the power factor will increase. The magnetude of current will increase, but power factor will decrease. The magnitude will both increase. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.125 p.u 0.75 p.u 0.5 p.u 0.25 p.u 0.125 p.u 0.75 p.u 0.5 p.u 0.25 p.u ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is/are the necessary conditions for parallel operation of alternators? Speed of alternators should be same Terminal voltage is same Both 1and 2 Frequency should be same Speed of alternators should be same Terminal voltage is same Both 1and 2 Frequency should be same ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 3 stack stepper motor has 12 teeth on stator as well as on rotor. Determine the step size when each stack excited? 10°. 45°. 30°. 24°. 10°. 45°. 30°. 24°. ANSWER DOWNLOAD EXAMIANS APP
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