Electrical Machines Minimum allowable resistivity of power transformer insulating oil is generally taken as 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 5 KVA transformer has a turns ratio of N1/N2 = 10. The impedance of primary winding is 3+j5 ohms while that of secondary winding is 0.5+j0.8 ohms. The impedance of transformer when referred to primary will be 3.5+j5.8 ohms 8+j13 ohms 53+j85 ohms 3.05+j5.08 ohms 3.5+j5.8 ohms 8+j13 ohms 53+j85 ohms 3.05+j5.08 ohms ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When a transformer is loaded, the secondary terminal voltage drops. That means power factor is zero. unity. leading. lagging. zero. unity. leading. lagging. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC generator beyond critical resistance will generate maximum power. maximum current. no voltage. maximum voltage. maximum power. maximum current. no voltage. maximum voltage. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A single-winding single-phase motor has high starting torque. low starting torque. zero starting torque. starting torque equal to full-load torque. high starting torque. low starting torque. zero starting torque. starting torque equal to full-load torque. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements : For a level compounded dc generator to run at constant voltage, the series field mmf must effectively compensate 1. armature reaction mmf 2.armature resistance drop 3. brush contact voltage drop Which of these statements is/are correct ? 2 alone 1 and 3 1, 2 and 3 1 and 2 2 alone 1 and 3 1, 2 and 3 1 and 2 ANSWER DOWNLOAD EXAMIANS APP
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