1. The advantage of the double squirrel cage induction motor over a single cage rotor is that it’s _______
A. Efficiency is higher
B. Power factor is higher
C. Slip is larger
D. Starting current is lower
2. A 16-pole, 3-phase, 60 Hz induction motor is operating at a speed of 150 rpm. The frequency of the rotor current of the motor in Hz is __________
3. Calculate the amplitude of the sinusoidal waveform z(t)=715sin(165πt+2π÷468).
4. R.M.S value of the sinusoidal waveform V=48sin(6.5πt+89π÷46.8).
A. 33.94 V
B. 33.56 V
C. 33.12 V
D. 33.78 V
5. The short circuit test on a 3-φ induction motor is conducted at a rotor speed of _______
B. < Ns
C. > Ns
6. If induction motor air gap power is 10 KW and mechanically developed power is 8 KW, then rotor ohmic loss will be _________ KW.
7. A 3-phase induction machine draws active power P and reactive power Q from the grid. If it is operated as a generator, then P and Q will be _________
A. Positive and Negative
B. Negative and Positive
C. Positive and Positive
D. Negative and Negative
8. The slope of the V-I curve is 39.1°. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line.
A. .81 Ω
B. .36 Ω
C. .75 Ω
D. .84 Ω
9. If induction motor air gap power is 48 KW and gross developed power is 28 KW, then rotor ohmic loss will be _________ KW.
10. The power factor of a squirrel cage induction motor is ___________
A. Low at light load only
B. Low at heavy loads only
C. Low at the light and heavy loads both
D. Low at rate load only