REAL POWER REVIEW AND TRAINING SPECIALISTS REFRESHER EE - MODULE 2

REAL POWER REVIEW AND TRAINING SPECIALISTS REFRESHER

INSTRUCTION: select the correct answer for each of the following questions. Mark only one answer for each
item by shading the box corresponding to the letter of your choice on the answer provided. STRICTLY
NOPERASURE ALLOWED. USE PENCIL NO. 1 ONLY.

MULTIPLE CHOICE

1. Two 3-phase transformers A and B having the same no-load line voltage ratio
3,300/400-V supply a load of 750 kVA at 0.707 lagging when operating in parallel. The rating of A is
500 kVA, its resistance is 2% and reactance 3%. The corresponding values for B are 250 kVA;1.5% and
4% respectively. Assuming that both transformers have star-connected secondary windings calculate
the load supplied by each transformer
A. 533 KVA/225 KVA C. 335 KVA/522 KVA
B.225 KVA/533 KVA D. 87.5 KVA/ 52.5 KVA
2. A 5 MVA, 123.8 KV/480 V, 5% impedance transformer is tapped at 13.8 kV line where the
Thevenin’s equivalent impedance is 1⁄2 ohm. Determine the fault current at the primary for a
three-phase fault at the secondary.
A. 10,500 amperes C. 4200 amperes
B. 3300 amperes D. 6060 amperes
3. Three resistors of 10-, 15-, and 20 ohm each are connected parallel. What is the equivalent
resistance?
A. 45 ohms B. 17.2 ohms C. 0.22 ohms D. 4.62 ohms
4. Calculate the R.M.S. value of the induced e.m.f. per phase of a 10-pole, 3-phase, 50-Hz alternator
with 2 slots per pole per phase and 4 conductors per slot in two layers.The coil span is 150°. The
flux per pole has a fundamental component of 0.12 Wb and a 20% third component.
A. 1100 V B. 106 BV C. 995 V D. 1000 V
5. A 25 ohm resistor connected in series with a coil of 50 ohm resistance and 150 mH inductance.
What is the power factor of the circuit?
A. 85% B. 80% C. 90% D. 75%
6. The current loads of four circuits are as follows:
Circuit no. 1 – 25 amperes
Circuit no. 2 – 38 amperes
Circuit no. 3 -18 amperes
Circuit no. 4 – 45 amperes
If the diversity factor is 1.5, what is the minimum ampacity of the feeder conductor?
A. 126 amperes C. 84 amperes
B. 189 amperes D. 152 amperes
7. A generator supplies three phase power to balance load. The voltage is 230 volts, the current is 18
amperes and the power factor is 85%. What is the power?
A. 3.6 kW B. 1.6 kW C. 6.1 kW D. 1.4 kW
8. A power plant gets water from a dam from a height of 122.45 meters at a rate of 10000 cubic
meters per minute. If the output of the plant is 15,000 kW, what is the plant efficiency?
A. 80% B. 70% C. 75% D. 65%
9. I fission, energy is produced when,
A. Chemical compound splits into its constituents °
B. Nuclear particles combined
C. Nuclear particles splits
D. Molecules combined
10. A magnetic circuit consists of silicon steel of 3, 000 permeability and air gap. The length of the steel
core is 10 cm. and the air gap is 2 cm. Both have same cross section of 1.5 sq. cm. A current of ½
ampere flows through the windings to produce 2351 maxwells flux. How many turns are there in
the coil?
A. 4120 turns B. 500 turns C. 2500 turns D. 12500 turns
11. The three phase unbalanced currents are:
Ia = 10 cis (-30°)
Ib = 0
Ic = 10 cis 150
Find the negative sequence current of phase a.s
A. 8.66 cis 30° B. 5.77 cis (-60°) C. -5.77 D. 5.77

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REAL POWER REVIEW AND TRAINING SPECIALISTS REFRESHER

12. What is the maximum length in km for a 1-phase transmission line having copper conductors of
0.775 cm2 cross-section over which 200 kW at unity power factor and at 3300 V can be delivered ?
The efficiency of transmission is 90 per cent. Take specific resistance as (1.725 × 10-8) Ω-m.
A. 13.6 Km B. 16.3 km C. 6.8 km D. 8.6 km

13. What arrester nominal rating shall be used in a 34.5 kV ungrounded system?
B. 27 k V B. 42 kV C. 22 kV D. 35 kV
14. A 100 : 5 transformer is used in conjunction with a 5-amp ammeter. If the latter reads 3.5 A, find the
line current
A. 70 A B. 50 A C. 0.175 A D. 10 A

15. A single phase induction motor is rated 5 HP, 75% power factor and 220 volts. What approximate
size of capacitor is necessary to raise the power factor to about 95%?
A. 3 KVAR B. 2 KVAR C. 2.5 KVAR D. 3.5 KVAR
16. It is a very powerful small component of a computer, which one?
A. Diode B. triode C. chip D. internet
17. A DC ammeter has an internal resistance of 0.1 ohm. A shunt of 1.010 x 10-3 ohm is connected to
the ammeter. What is the multiplier of the set up?
A. 80 B. 100 C. 50 D. 10
18. In a particular R-L series circuit a voltage of 10 V at 50 Hz produces a current of 700 mA while the
same voltage at 75 Hz produces 500 mA. What are the values of R and L in thecircuit ?
A. 6.9 ohms & 40 mH C. 6.9 ohms & 20 mH
B. 9.6 ohms & 40 mH D. 9.6 ohms & 20 mH
19. TV signal is transmitted to the air thru _________.
A. Electron transmitter B. cyclone C. antenna D. sender
20. Which of the following is not one of the classes of surge arresters?
A. Transmission class B. Distribution class C. Station class D. Intermediate class
21. A 50 and 100 microfarad capacitors are connected in series and across a 100 sin (ωt + 30) voltage.
Write the equation of the current.
A. 1.26 sin (ωt + 120°) C. 5.65 sin (ωt + 120°)
B. B. 1.26 sin (ωt + 90°) D. 5.65 sin (ωt + 90°)
22. Two resistances of 10 and 15 ohms, each respectively are connected in parallel. Two are then
connected in series with a 5-ohm resistance. If then connected across a 12 volt battery, what are
the current and the power?
A. 1.2 A, 17.28 watts C. 1.09 A, 13.1 watts
B. B. 0.96 A, 11.52 watts D. 1.5 A, 20.25 watts
23. A load of 1,000 kW at 0.8 p.f. lagging is received at the end of a 3-phase line
10 km long. The resistance and inductance of each conductor per km are 0.531 W and 1.76 mH
respectively. The voltage at the receiving end is 11 kV at 50 Hz. What would be the reduction in the
line loss if the p.f. of the load were improved to unity?
A. 24.66 KW B. 26.46 KW C. 25.66 KW D. 26.66 KW
24. Two resistances of 10 and 15 ohms each respectively are connected in parallel. Two are then
connected in series with a 5 ohm resistance. What is the equivalent resistance?
A. 11 ohms B. 12 ohms C. 10 ohms D. 9 ohms
25. The underground system cannot be operated above
A. 440 V B. 11 Kv C. 33 Kv D. 66 kV

26. The resistance of a wire is 126.48 ohms at 100°C and 100 ohms at 30°C. Determine the temperature
coefficient of copper at 0°C.
A. 0.00427 B. 0.00615 C. 0.0256 D. 0.0356
27. A certain shunt motor has an armature resistance of 0.05 ohms. It draws 50 amperes at a terminal
voltage of 120. Assume other miscellaneous losses at 1%. Determine the output horsepower of the
motor.
A. 8.5 HP B. 7.1 HP C. 6.8 HP D. 7.8 HP
28. A coil of a 50-ohm resistance an of 150-mH inductance is connected in parallel with a 50 μF
capacitor. What is the power factor of the circuit?

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REAL POWER REVIEW AND TRAINING SPECIALISTS REFRESHER EE - MODULE 2
REAL POWER REVIEW AND TRAINING SPECIALISTS REFRESHER

A. 80% B. 50% C. 70 % D. 60%

29. The phenomenon of rise in voltage at the receiving end of the open-circuited or lightly loaded
line is called the
` A Seeback effect (b) Ferranti effect (c) Raman effect (d) none of the above
30. The critical resistance of the d.c. generator is the resistance of
(a) armature (b) field (c) load (d) brushes
31. A deep well pumps water into an open reservoir at the rate of 100 gpm. The water table is 200 ft.
below the output pipe. The whole system has an overall efficiency of 70%. What shall be the
minimum hp of the pump?
A. 5.3 HP B. 8.7 HP C. 12.4 HP D. 7.2 HP
32. Three equal positive charges of 10 stat coulomb are located at the vertices of an equilateral triangle
of 2 cm leg. What is the magnitude of the force acting on each charge?
A. 12.5 dynes B. 25 dynes C. 43.3 dynes D. 50 dynes
33. Piezo electricity principle is applied in one of the following:
A. Ultrasound equipment C. Microphones
B. Thermometer D. TV sets
34. A load of 20 + j35 ohms is connected across a 220 volts source. Determine the power factor and the
vars.
A. 49.6%, 1,042 vars C. 52.2%, 1,023 vars
B. 85.3 %, 975 vars D. 42.3%, 1,087 vars
35. A certain laminated steel core has a permeability of 3000. The length is 5 cm and the cross section is
2 sq.cm. What is the reluctance?
A. 7,500 B. 8.33 x 10-4 C. 1,200 D. 2.5
36. A 15-mH inductor is in series with a parallel combination of an 80 Ω resistor and 20 μF capacitor. If
the angular frequency of the applied voltage is ω = 1000 rad/s, find the admittance of the network.
A. 0.0238 + j 0.022 Siemens C. 0.022 + j. 0.0238 Siemens
B. 0.0238 - j 0.022 Siemens D. 0.022 - j. 0.0238 Siemens
37. A generator is rated 100 MW, 13.8 kv and 90% power factor. The ration of the effective resistance
to ohmic resistance is 1.5. The ohmic resistance is obtained by connecting two terminals to a dc
source. The current and voltage are 87.6 amperes and 6 volts respectively. What is the effective
resistance per phase?
A. 0.0512 ohm B. 0.0685 ohm C. 0.342 ohm D. 0.0617 ohm
38. A certain capacitor is charged at 48 volts after which its stored energy is 5.76 x 10-2 joules. What is
the frequency of the rotor current at full load?
A. 2 farads B. 60 microfarads C. 30 microfarads D. 50 microfarads
39. A 13.8 kV/ 480 V, 10 MVA three phase transformer has 5% impedance. What is the impedance in
ohms referred to the primary?
A. 0.952 ohm B. 0.03 ohm C. 5.125 ohms D. 9.01 ohm
40. A long shunt d.c. compound generator delivers 110 kW t 220 V. If ra = 0.01 ohm, rse = 0.002 ohm,
and shunt field has a resistance of 110 ohms, calculate the value of the induced e.m.f.
A. 226.024 V B. 262.024 V C. 260.024 V D. 220.024 V
41. The induced e.m.f. in the armature conductors of a d.c. motor is
A. sinusoidal C. trapezoidal
B. rectangular D. alternating
42. The illumination of a room is being designed. The data are a follows.
Room length = 30 ft Room width = 20 ft
Coefficient of utilization = 0.6 Maintenance factor = 70%
Required foot-candles = 50 Lumens per lamp = 3300
Watts per lamp = 53 Voltage = 220
Power factor = 75
What is the total current of the lamps required to satisfy the requirement?
A. 21 amperes B. 15 amperes C. 7 amperes D. 25 amperes
43. In the list below, which one is not a type of present day nuclear power plant?
A. Boiling water reactor C. Low pressure reactor
B. Fusion-fission reactor D. Fast breeder reactor
44. A d.c. shunt machine while running as generator develops a voltage of 250 V
at 1000 r.p.m. on no-load. It has armature resistance of 0.5 Ω and field resistance of 250 Ω. When
the machine runs as motor, input to it at no-load is 4 A at 250 V. Calculate the speed of the machine
when it runs as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4 %.

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REAL POWER REVIEW AND TRAINING SPECIALISTS REFRESHER EE - MODULE 2
REAL POWER REVIEW AND TRAINING SPECIALISTS REFRESHER

A.885 rpm B. 1040 rpm C. 960 rpm D. 1200 rpm

45. A 4-pole series motor has 944 wave-connected armature conductors. At a certain load, the flux per
pole is 34.6 mWb and the total mechanical torque developed is 209 N-m. Calculate the speed at
which it will run with an applied voltage of 500 V. Total motor resistance is 3 ohm.
A.350 rpm B. 300 rpm C. 404 rpm D. 200 rpm
46. Three impedances each of 10 +j5 ohms are connected delta on a balance three phase source. If the
equation of the phase voltage is Van = 120 sin ωt, what is the equation of the current through the
impedance connected across phase A and B?
A. 20.02 sin (ωt - 22°) C. 16.21 sni (ωt – 56.56°)
B. B. 18.59 sin (ωt – 3.44°) D. 21.32 sin (ωt – 8.15°)
47. A four pole dc generator with lap winding has 48 slots and 4 elements per slot. How many coils does
it have?
A. 48 B. 384 C. 192 D. 96
48. A 50 MVA, 33kV/11 kV, three phase, wye-delta, connected transformer has a 3% impedance. What
is the percent impedance at 100 MVA base and 34.5 kV base?
A. 1.639% B. 5.49% C. 5.74% D. 6.56%
49. A230 kV transmission line has an impedance of 5 cis 78 ohms. The sending end power is 100MW at
230 kV and 85% power factor. What is the voltage at the other end?
A. 225.4kV B. 226.3 kV C. 223.2 kV D. 228.2 kV
50. Three resistors of 10, 15 and 20 ohms each are connected in parallel. What is the total
conductance?
A. 0.217 mhos B. 3.41 mhos C. 4.62 mhos D. 0.52 mhos

*** END ***

SUBMIT THIS TEST QUESTION SET TOGETHER WITH THE ANSWER SHEET TO YOUR WATCHERS. BRINGING THE
TEST QUESTION SET OUT OF THE ROOM WILL BE A GROUND FOR DISCIPLINARY ACTION.

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