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 _________
1.Positive and Negative
2.Negative and Positive
3.Positive and Positive
4.Negative and Negative
At low values of slip the electromagnetic torque is directly proportional to ___________
1.s
2.s2
3.s3
4.s4
Calculate the total heat dissipated in a rotor resistor of 14.23 ? when .65 A current flows through it.
1.6.45 W
2.6.01 W
3.6.78 W
4.6.98 W
If induction motor air gap power is 2 KW and mechanically developed power is 1 KW then rotor ohmic loss will be _________ KW.7.
1.1
2.2
3.3
4.4
If induction motor air gap power is 48 KW and gross developed power is 28 KW then rotor ohmic loss will be _________ KW.
1.10
2.20
3.30
4.40
In the rotor voltage injection method when an external voltage source is in phase with the main voltage then speed will ___________
1.Increase
2.Decrease
3.Remain unchanged
4.First increases then decrease
The slope of the V-I curve is 1.1�. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line.
1..019 ?
2..036 ?
3..075 ?
4..084 ?
What is the formula for the maximum active power in the cylindrical rotor synchronous machine? (Eb represents armature emf Vt represents terminal voltage ? represents rotor angle X represents reactance)
1.Eb�Vt�sin?�X
2.Eb�Vt2�X
3.Eb2�Vt�sin?�X
4.Eb�Vt�X
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 __________
1.20
2.40
3.30
4.10
A 2-pole 3-phase ______ Hz induction motor is operating at a speed of 550 rpm. The frequency of the rotor current of the motor in Hz is 2.
1.9.98
2.9.71
3.9.12
4.9.37
A 20-pole 3-phase 90 Hz induction motor is operating at a speed of _______ rpm. The frequency of the rotor current of the motor in Hz is 20.
1.418.56
2.420.12
3.421.23
4.422.45
A 32-pole 3-phase 70 Hz induction motor is operating at a speed of 112 rpm. The frequency of the rotor current the motor in Hz is __________
1.40.2
2.46.1
3.40.1
4.40.6
Calculate mark to space ratio if the system is on for 26.3 sec and off for 24.2 sec.
1.1.086
2.1.042
3.1.214
4.1.876
Calculate mark to space ratio if the system is on for 4.3 sec and off for 78.2 sec.
1.0.054
2.0.047
3.0.039
4.0.018
Calculate the active power in a .154 H inductor.
1.22 W
2.14 W
3.45 W
4.0 W
Calculate the active power in a .89 H inductor.
1.1.535 W
2.0 W
3.2.484 W
4.1.598 W
Calculate the active power in a 168.12 H inductor.
1.65 W
2.0 W
3.68 W
4.64 W
Calculate the active power in an 8.12 F capacitor.
1.89 W
2.41 W
3.0 W
4.48 W
Calculate the amplitude of the sinusoidal waveform
1.710
2.715
3.716
4.718
Calculate the amplitude of the sinusoidal waveform z(t)=.27sin(.369?t+.142?�4.25).
1.0.287
2.0.27
3.0.287
4.0.216
Calculate the average value of the sinusoidal waveform x(t)=848sin(1.65?t+2?�0.68).
1.0
2.78 V
3.15 V
4. 85 V
Calculate the condition for maximum voltage regulation in the synchronous machine.
1.?=?s
2.?=2?s
3.?=4?s
4.?=8?s
Calculate the line current in the delta connection when phase current=17 A.
1.29.44 A
2.24.64 A
3.23.48 A
4.26.56 A
Calculate the line voltage in star connection when phase voltage=45 V.
1.77.9 V
2.77.6 V
3.77.2 V
4.77.8 V
Calculate the line voltage in the delta connection when phase voltage=45 V.
1.46 V
2.47 V
3.45 V
4.78 V
Calculate the maximum value of slip when rotor resistance is 2 ? and rotor reactance is 3 ?.
1.0.66
2.0.33
3.0.44
4.0.99
Calculate the moment of inertia of the sphere having a mass of 8.4 kg and radius of 61 cm.
1.3.124 kgm2
2.3.125 kgm2
3.4.545 kgm2
4.5.552 kgm2
Calculate the peak value of sinusoidal waveform if the r.m.s value is 21 V.29.69 V
1.29.69 V
2.48.74 V
3.69.23 V
4.25.74 V
Calculate the power factor angle during the resonance condition.
1.0�
2.10�
3.80�
4.90�
Calculate the power factor if the power angle is 36.86�.
1.0.8
2.0.4
3.0.6
4.1
Calculate the reactive power in a 2.2 ? resistor.
1.1.5 VAR
2.2.6 VAR
3.0 VAR
4.1.9 VAR
Calculate the reactive power in a 7.2545 ? resistor.
1.1.221 VAR
2.2.611 VAR
3.0 VAR
4.1.997 VAR
Calculate the time period of the waveform i(t)=sin(?t+6?�4)+sin(?t+5?�6).
1.2 sec
2.4 sec
3.5 sec
4.3 sec
Calculate the time period of the waveform v(t)=12sin(8?t+8?�15)+144sin(2?t+?�6)+ 445sin(?t+7?�6).
1.8 sec
2.4 sec
3.7 sec
4.3 sec
Calculate the time period of the waveform z(t)=24sin(?t+?�4)+4sin(2?t+?�6).
1.2 sec
2.3 sec
3.4 sec
4.1 sec
Calculate the total heat dissipated in a resistor of 44 ? when 0 A current flows through it.
1.0 W
2.2 W
3.1.5 W
4..3 W
Calculate the total heat dissipated in a resistor of 50 ? when 1.4 A current flows through it.
1.98 W
2.92 W
3.91 W
4.93 W
Calculate the total heat dissipated in a rotor resistor of 21 ? when .81 A current flows through it.
1.13.77 W
2.12.56 W
3.46.45 W
4.13.98 W
Calculate the value of the duty cycle if the system is on for 1 sec and off for 0 sec.1
1.1
2.0.4
3.0.1
4.0.6
Calculate the value of the duty cycle if the system is on for 5 sec and off for inf sec.12.
1.0
2.0.4
3.0.2
4.0.1
Calculate the value of the frequency of the AC supply in India.
1.0 Hz
2.50 Hz
3.49 Hz
4.60 Hz
Calculate the value of the time period if the frequency of the signal is .07 sec.
1.14.28 sec
2.14.31 sec
3.14.23 sec
4.14.78 sec
Calculate the voltage regulation in the synchronous machine if the no-load voltage is 12 V and the full load voltage is 15V.
1.-20%
2.-40%
3.-60%
4.-80%
If induction motor air gap power is 1.8 KW and gross developed power is .1 KW then rotor ohmic loss will be _________ KW.
1.1.7
2.2.7
3.3.7
4.4.7
If induction motor air gap power is 10 KW and mechanically developed power is 8 KW then rotor ohmic loss will be _________ KW.
1.1
2.2
3.3
4.4
If induction motor air gap power is 67 KW and mechanically developed power is 26 KW then rotor ohmic loss will be _________ KW.
1.41
2.42
3.43
4.44
If induction motor rotor power is 157.5 KW and gross developed power is 79.9 KW then rotor ohmic loss will be _________ KW.
1.77.5
2.77.6
3.76.9
4.77.1
If induction motor rotor power is 157.5 KW and gross developed power is 79.9 KW then rotor ohmic loss will be _________ KW.
1.77.5
2.77.6
3.76.9
4.77.1
In a DC series motor the e.m.f developed is proportional to _______
1.N�Ia
2.N�Ia2
3.N�Ia3
4.N�Ia.5
In a DC shunt motor the e.m.f developed is proportional to ___________
1.Ia
2.Ia2
3.Ia3
4.Iao
In the chopper circuit commutation times are _______
1.Current commutation is equal to voltage commutation
2.Current commutation is less as compared to that of voltage commutation
3.Current commutation is more as compared to that of voltage commutation
4.Both commutation techniques are not comparable
In the rotor voltage injection method when an external voltage source is in opposite phase with the main voltage then speed will ___________
1.Increase
2.Decrease
3.Remain unchanged
4.First increases then decrease
R.M.S value of the periodic square waveform of amplitude 72 V.
1.72 V
2.56 V
3.12 V
4.33 V
R.M.S value of the sinusoidal waveform q(t)=2.11cos(87.25t+78?�478.23).
1.1.49 V
2.1.56 V
3.1.12 V
4.1.78 V
R.M.S value of the sinusoidal waveform v(t)=211sin(7.25t+7?�78.3).
1.149.19 V
2.156.23 V
3.116.57 V
4.178.64 V
R.M.S value of the sinusoidal waveform V=48sin(6.5?t+89?�46.8).
1.33.94 V
2.33.56 V
3.33.12 V
4.33.78 V
The advantage of the double squirrel cage induction motor over a single cage rotor is that its _______
1.Efficiency is higher
2.Power factor is higher
3.Slip is larger
4.Starting current is lower
The generated e.m.f from 4-pole armature having 1 conductors driven at 1 rev/sec having flux per pole as 10 Wb with wave winding is ___________
1.30 V
2.40 V
3.70 V
4.20 V
The most suitable control-motor application is __________
1.AC shunt motor
2.DC separately motor
3.AC one-phase induction motor
4.DC shunt motor
The no-load circuit test on a 3-? induction motor is conducted at a rotor speed of _______
1.Zero
2.< Ns
3.> Ns
4.Ns
The phase difference between voltage and current in the choke coil.
1.90�
2.40�
3.50�
4.68�
The power factor of a squirrel cage induction motor generally is ___________
1..6-.8
2..1-.2
3..2-.4
4..5-.7
The power factor of a squirrel cage induction motor is ___________
1.Low at light load only
2.Low at heavy loads only
3.Low at the light and heavy loads both
4.Low at rate load only
The power factor of a squirrel cage induction motor is ___________
1.High at light load only
2.High at heavy loads only
3.Low at the light and heavy loads both
4.Low at rate load only
The short circuit test on a 3-? induction motor is conducted at a rotor speed of _______
1.Zero
2.< Ns
3.> Ns
4.Ns
The slope of the V-I curve is 13.89�. Calculate the value of resistance.
1..247 ?
2..345 ?
3..231 ?
4..222 ?
The slope of the V-I curve is 180o. Calculate the value of resistance. The graph is parallel to the x-axis.9.
1.1.47 ?
2.1.81 ?
3.0 ?
4.4.12 ?
The slope of the V-I curve is 35.48�. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line.
1.0.452 ?
2.0.462 ?
3.0.752 ?
4.0.712 ?
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.
1..81 ?
2..36 ?
3..75 ?
4..84 ?
The slope of the V-I curve is 9.1�. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line.
1.16 ?
2.26 ?
3.25 ?
4.44 ?
The value of slip at which maximum torque occurs ________
1.R2�X2
2.4R2�X2
3.2R2�X2
4.R2�3X2
What is the unit of the distance?
1.m
2.m/s
3.atm/m
4.Volt