Electrical Engineering Mastery Test 3 | REE Pre-Board Exam

REE BOARD EXAM PRE-TEST 3: The Real Deal for Electrical Engineers

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⇐ Electrical Engineering Mastery Test 2 | REE Pre-Board Exam

Choose the letter of the best answer in each questions.

1. When a V-V system is converted into ∆-∆ system, increase in the capacity of the system is _____ percent.

A. 73.2

B. 86.8

C. 66.6

D. 50

2. A 230-volt, 3 – phase system has a load of 7.07 + j7.07 ohms in wye connection. What is the current?

A. 9.39 – j 9.39

B. 16.3 + j16.3

C. 16.3 – j 16.3

D. 9.39 + j 9.39

3. What is the minimum number of wattmeter/s required for measuring the power of a three-phase balanced load?

A. Four

B. Two

C. One

D. Three

4. In transmission lines, the most effective protection against lightning strikes is one of the following. Which one is this?

A. Ground wire

B. Lightning rods

C. Lightning arresters

D. Overhead Static wires

5. Given the following sets of per-unit symmetrical components of phase A currents, determine the phase B current.

Ia₀ = 1 cis 75 deg

Ia₁ = 1 cis 15 deg

Ia₂ = 1 cis -45 deg

A. -1.414 + j1.414 pu

B. 1.932 + j 0.518 pu

C. 0.259 + j0.966 pu

D. 0.516 + j 1.931 pu

6. What is the maximum plug and cord rating of a 30-A branch circuit?

A. 24 A

B. 30 A

C. 26 A

D. 28 A

7. A 69 kV, three-phase transmission line is 50 km long. The resistance per phase is 0.3006 ohm per mile and the inductance per phase is 0.451 ohm per mile. Neglect the shunt capacitance. Using the short-line model, what is the voltage regulation when the line is supplying a three-phase load of 20 MVA at 0.80 lagging power factor at 69 kV?

A. 6.3 %

B. 6.7%

C. 7.6 %

D. 7.2 %

8. For a series RLC circuit with elements R = 50 Ω, L = 8 mH and C = 2.22 µF, what is the equivalent impedance of the circuit given that its frequency is 796 Hz?

A. 50 – j150 ohms

B. 50 – j50 ohms

C. 50 + j150 ohms

D. 50 + j50 ohms

9. A 440 V, 60 Hz, 6-pole, 3-phase induction motor has a rotor input power of 33 kW at rated voltage and frequency. Under this condition, the rotor emf makes 126 complete cycles/minute. Find the rotor resistance in ohms/phase if the rotor current is 60 A/phase.

A. 0.107

B. 0.011

C. 0.0107

D. 0.118

10. What is the reserve capacity, if the maximum demand of generation of power is 50 MW, the load factor of the plant is 60% and the plant capacity factor is 50%?

A. 10 MW

B. 25 MW

C. 50 MW

D. 60 MW

11. A voltage source vi(t) supplies the network of a resistor of 1 ohm that is connected in series with a parallel combination of inductor with 1 H inductance and another resistor with 1 ohm resistance. Find the transfer function G(s) = V₀(s)/Vi(s) provided that v₀(t) is the voltage across 1 ohm resistance in the parallel combination.

A. V₀/Vi = s/(s – 2)

B. V₀/Vi = s/(s + 2)

C. V₀/Vi = 1/(s – 2)

D. V₀/Vi = 1/(s + 2)

12. A 4 pole, 60Hz, induction motor, has a full load slip of 5%. What is the full load rotor speed?

A. 1710 rpm

B. 1750 rpm

C. 1730 rpm

D. 1780 rpm

13. A delta-connected load has a per-phase impedance of 29.8757 – j25.0687. It is supplied with a wye-connected balanced source through a 3-phase line with 4 ohms resistance. The voltage sequence is given by V_a = 277 cis -30 deg, V_b = 277 cis -150 deg, V_c = 277 cis 90 deg. What is the line A current?

A. 6.5 + j 0.75

B. 6.5 – j 0.75

C. 17 – j 0.267

D. 17 + j 0.267

14. The type of AC distribution system commonly used to supply both light and power is the:

A. Three-phase wye system without neutral wire

B. Open delta system

C. Three-phase delta system

D. Three-phase wye system with neutral wire

15. The voltage phasors of a three-phase balance voltage system are VRY = 230 cis 30 deg volts and VYB = 230 cis 270 deg volts. What is the phase sequence of the voltage system?

A. BYR

B. RBY

C. YRB

D. RYB

16. A lamp gives an average output of 628 lumens. What is its MSCP?

A. 45

B. 50

C. 49

D. 40

17. In two two-winding unloaded transformer, the flux linking the primary and secondary windings are 10 mWb and 8 mWb, respectively. What is the coupling coefficient?

A. 0.8

B. 0.6

C. 0.7

D. 0.9

18. In dwelling units with a hallway of 3 m or more in length, at least how many receptacles outlet/s shall be installed?

A. 1

B. 3

C. None

D. 2

19. The Z_bus of a system is Z₁₁ = 0.1; Z₁₂ = 0.1, Z₁₃ = 0.1; Z₂₂ = 0.2; Z₃₃ = 0.30. If a three-phase fault occurs at Bus 2, the p.u. fault current in each phase is ______.

A. 5 pu

B. 5(sqrt 2) pu

C. 10(sqrt 3) pu

D. 10 pu

20. For a fully transposed transmission line _____

A. Positive, negative, and zero sequence impedances are equal

B. Zero and positive sequence impedances are equal

C. Negative and zero sequence impedances are equal

D. Positive and negative sequence impedances are equal

21. A transfer function is as C(s) = 5/s(s + 5), find the time constant.

A. 0.1 s

B. 1 s

C. 0.2 s

D. 5 s

22. A voltage source vi(t) supplies the network of a resistor of 1 ohm that is connected in series with a parallel combination of another 1 ohm resistance and an inductor of 1 ohm connected in series with 1 F capacitance. Find the transfer function G(s) = Vo(s)/Vi(s) provided that v₀(t) is the voltage across 1 F capacitance.

A. V₀/Vs = 2/((2s² + s + 2)

B. V₀/Vs = s/((2s² + s + 2)

C. V₀/Vs = 2s²/((2s² + s + 2)

D. V₀/Vs = 1/((2s² + s + 2)

23. Given that a transfer function is T(s) = 2/(s – 3), find the system response y(t) to an input x(t) = u(t), a unit step, assuming zero initial conditions.

A. y(t) = -2/3 – (2/3)e³ᵗ

B. y(t) = 2/3 + (2/3)e³ᵗ

C. y(t) = -2/3 + (2/3)e³ᵗ

D. y(t) = 2/3 – (2/3)e³ᵗ

24. Two generators operating in parallel supply a total load current of 150 A. The terminal p.d of one machine falls from 250V on no-load to 234 V when its current output is 100 A. The terminal p.d of the other machine falls from 250 V on no load to 230 V when its armature current is 80A. The external characteristics are rectilinear. Determine the common terminal voltage.

A. 217.9 V

B. 235.37 V

C. 288.7 V

D. 218.46 V

25. The direction of induced EMF can be found by ______.

A. Kirchhoff`s Law

B. Fleming`s Right Hand Rule

C. Lenz`s Law

D. Fleming`s Left Hand Rule

26. A copper wire of certain length and resistance is drawn out to four times its length without change in volume, the new resistance of wire becomes _______.

A. 1/16 times

B. 16 times

C. double

D. 4 times

27. What is the advantage of a synchronous motor?

A. All of the choices

B. It can be constructed with wider air gaps than induction motors which is an advantage, mechanically.

C. It operates at higher efficiencies.

D. It gives constant speed from no load to full load.

28. An autotransformer is used to connect a 13.2 kV distribution line to a 13.8 kV distribution line. It must be capable of handling 2000 kVA. There are three-phases connected Y-Y with their neutral solidly grounded. What must be the N_C/N_SE turns ratio to accomplish this connection?

A. 26

B. 24

C. 22

D. 20

29. If the torque angle is continuously increasing, the system will become __________.

A. oscillatory stable

B. unstable

C. stable

D. asymptotically stable

30. Ds is the GMR of each subconductor of a four subconductor bundled and d is the bundle spacing. What is the GMR of the equivalent single conductor?

A. 1.09 (Ds*d)^1/2

B. 1.09 (Ds*d³)^1/4

C. 1.09 (Ds*d²)^1/3

D. 1.09 (Ds²*d²)^1/4

31. A 10-ohm resistor is connected in parallel to the impedance of z = 3 +j4. What is the power factor?

A. 0.6

B. 0.909

C. 0.809

D. 0.8

32. Which of the following depicts per-unit value of a quantity?

A. Twice of the actual quantity in any unit

B. Ratio of base or reference value of quantity in the same unit to actual quantity in any unit

C. Ratio of actual quantity in any unit to base or reference value of quantity in the same unit

D. Half of the actual quantity in any unit

33. A 3-phase, 4-pole, star-connected alternator has 60 slots with 2 conductors per slot. The pitch of the coil is 3 less than the pole pitch. The flux per pole is 0.125 Wb, calculate the induced voltage per phase of this alternator.

A. 974 Volts

B. 505 Volts

C. 874 Volts

D. 605 Volts

34. The zero-sequence current of a generator for line-to-ground faults is j3.0 pu. Then the current through the neutral during the fault is:

A. j3.0 pu

B. j1.0 pu

C. j9.0 pu

D. j0.30 pu

35. A rice mill will be served by two units of 50 kVA transformers, 7.62 kV/240 V. The transformers will be installed as open delta bank to serve the three-phase load of the rice mill. What is the maximum kVA load that this bank can carry without overloading?

A. 100

B. 50

C. 75.5

D. 86.6

36. A three–phase, 4-wire, Y-connected system with 220 V per phase is connected to three loads. 10 Ω, 20 cis 20 deg Ω, 12 cis -35 deg Ω to phases 1,2, and 3, respectively. Find the current in the neutral line assuming 1 – 3 – 2 phasing.

A. 22.9 cis -18.8 deg A

B. 22 cis 18.8 deg A

C. 3.15 cis 167 deg A

D. 13.08 cis 167 deg A

37. ______ is a series type of unbalanced fault that occurs in a power system.

A. Double line-to-ground fault

B. Single line-to-ground fault

C. Open conductor fault

D. Line-to-line fault

38. A lead storage battery is rated at 12 Volts. If the internal resistance is 0.05 ohms, what is the maximum power transfer that can be delivered to the load?

A. 1200 watts

B. 1096 watts

C. 720 watts

D. 540 watts

39. Bundled conductors are used in transmission lines, the effective capacitance and inductance will respectively:

A. Remain same and increase

B. Increase and decrease

C. Decrease and remain same

D. Decrease and increase

40. Given three unbalanced line currents I_a = 0+j12 A, I_b = 5 – j10 A and I_c = – 10 – j5 A. Find the negative sequence component of I_c in amperes.

A. 2.25cis-14.3 deg

B. 3.12cis-14.3 deg

C. 3.12cis14.3 deg

D. 2.25cis14.3 deg

41. Which of the following scientific principles is mainly behind the generation of hydroelectric power?

A. Conversion of electrical energy into gravitational energy

B. Conversion of gravitational potential energy into electrical energy

C. Conversion of kinetic energy into electrical energy

D. Conversion of mechanical energy into electrical energy

42. Given a circuit with an applied voltage v = 340sin(ωt-60) V and a resulting current of i =13.3sin (ωt – 48.7) A. What is the real power of the circuit?

A. 2217 Watts

B. 480 Watts

C. 2200 Watts

D. 443 Watts

43. An 8-ohm resistor is connected in series with an inductive coil and the combination is connected across a 120 V, 60 Hz source. A voltmeter connected across the resistor reads 32 V and 104 V when connected across the coil. Determine the resistance of the coil.

A. 12 ohms

B. 9 ohms

C. 8 ohms

D. 10 ohms

44. A current is given by this equation i = 2t³ + t² + 3, a capacitor has an initial charge of 6.38 Coulomb. What should be the charge of the capacitor after 5 seconds?

A. 385

B. 362

C. 375.8

D. 369

45. To equalize the sending and receiving voltages, impedance is connected at the receiving end of a transmission line having; the following ABCD parameters A = D = 0.9/0°, B = 200/90°. What is the value of the impedance connected?

A. 2000/90° Ω

B. 1000/90° Ω

C. 2000/0° Ω

D. 1000/0° Ω

46. Load flow study is carried out for __________.

A. load frequency control

B. fault calculation

C. system planning

D. stability Studies

47. In a basic transmission line, the line-to-line voltage at the receiving end without load is 660 V; and it is 420 V with full load. What is the percentage of voltage regulation?

A. 63.67%

B. 73.41%

C. 36.36%

D. 57.14%

48. A room with dimensions 75 ft x 36 ft x 13 ft requires 50 foot–candles, lamp lumen output 3200 maintenance factor is 0.7, coefficient of utilization is 0.46. Arranged in 4 rows and 4 bays. How many lamps in bays?

A. 4

B. 10

C. 6

D. 8

49. What is the equivalent area in sq. inch for a conductor 336,500 circular mill?

A. 0.678

B. 0.264

C. 0.777

D. 0.442

50. Step potential and touch potential is associated with:

A. Voltage rise in the substation

B. Communication systems

C. Earthing of the substation

D. High voltage transmission