DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

Q.1 A three-phase induction motor is supplied through a 50 Hz supply. Find the frequency of the rotor current for 4% slip.

1. 5 Hz
2. 10 Hz
3. 2.5 Hz
4. 2 Hz

Correct Option: 4

Q.2 Which of the following is NOT an effect of hunting in synchronous motors?

1. Reduction in mechanical stress on the rotor shaft
2. Increase in the machine temperature
3. Increase in machine losses
4. Loss of synchronism

Correct Option: 1

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

Q.4 In case of S.L. type screened cables, S.L. stands for

1. Service Lead
2. Shorted Lead
3. Separate Lead
4. Selective Lead

Correct Option: 3

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

Q.5 In transmission lines, the voltage regulation is negative, only if:

1. Load P.F. is unity
2. Load P.F. is lagging
3. Load P.F. is leading such that (IR cos OR)>(I XL sin OR)
4. Load P.F. is leading such that (I R cos OR)<(IXL sin OR)

Correct Option: 4

Q.6 For which of the following conditions does an induction machine act as an electric break?

1. Slip is negative
2. Slip is positive and less than 1
3. Slip is zero
4. Slip is positive and greater than 1

Correct Option: 4

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

Q.8 are the devices that are used to detect the ground fault for ungrounded A.C. systems.

1. Ground detectors
2. Spark detectors
3. Line detectors
4. Phase detectors

Correct Option: 1

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

Q.9 A series RL circuit is supplied through a 100 V, 50 Hz supply. If the RMS current in the circuit is 3 A, then find the apparent power in the circuit.

1. 300 VA
2. 212 VA
3. 424 VA
4. 150 VA

Correct Option:1

Q.12 A coil of 8 H is tightly coupled with another coil of 18 H. Find the mutual inductance between the two coils.

1. 10 H
2. 18 H
3. 12 H
4. SH

Correct Option: 3

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

Q14. Identify whether the following statements related to DC machines are true or false. 1) Interpoles are also called compoles.
2) The interpole windings are connected in series with the armature.

1. 1) True, 2) False
2. 1) False, 2) True
3. 1) False, 2) False
4. 1) True, 2) True

Correct Option: 4

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

Q.15 Oil-filled cables can be used from up to

1.22 kV; 33 kV
2. 66 kV; 230 kV
3. 11 kV; 22 KV
4. 33 kV; 66 kV

Correct Option: 2

Q.16 An EMF of 0.25 V is induced in a coil when the flux changes at a rate of 1 mWb/s. Calculate the number of turns in the coil.

1. 250
2 50
3. 25
4. 125

Correct Option: 1

Q17. In a 20-pole synchronous motor, if the rotor is retarded by 0.5° (mechanical) from its synchronous position, then compute the rotor displacement in electrical degrees.

1. 15°
2. 10°
3.50
4. 2.5°

Correct Option: 3

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

Q.18 A voltage source of v = 20 sin at volts is connected across a 5 2 resistor. Find the power dissipated in the resistor.

1. 60 sin2 t
2. 80 sin2 t
3. 100 sin2 t
4. 40 sin2 t

Correct Option: 2

Q.19 Arrange the following materials in the ascending order of their resistivity:
Carbon, glass, copper

1. Carbon, glass, copper
2. Copper, carbon, glass
3. Copper, glass, carbon
4. Glass, copper, carbon

Correct Option: 2

Q.20 An 8-pole lap-connected DC generator has 480 conductors, and it generates 500 V. If the flux per pole is 50 mWb, find the speed of the generator.

1. 1500 rpm
2. 1000 rpm
3. 1250 rpm
4. 750 rpm

Correct Option: 3

DDA JE Electrical ME 3 April 2023 Shift 2 Part 1

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