REGISTERED ELECTRICAL ENGINEERING Pre-Board Examination 8:00 a.m. -12:00 nn.
Friday. August 29, 2003
ELECTRICAL ENGINEERING
SET A
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 sheet provided. STRICTLY NO ERASURES ALLOWED. Use pencil no. 2 only.
MULTIPLE CHOICE
1. An ammeter has a full deflection current of 100 mA. If the same ammeter uses a 9 volt dry cell and it has
a full scale reading of 1 ampere, what is the value of the shunt resistor in ohms?
A.9
B.10
C.100
D.900
2. In RC circuits, the one time constant indicates the time it takes a capacitor to charge up to what percent
of the charging voltage?
A.0%
B.31%
C.63%
D.67%
3. A 3-phase motor takes 10 KVA at 0.6 power factor lagging from a source of 230 volts. It is in parallel
with a balanced delta load having 16 ohms resistance and 12 ohms capacitive reactance in series in
each phase. What is the power factor of the combination
D. 0.967 ldg
A. 0.785 lag
B.0.967 lag/
C. 0.785 ldg
4. A 25 KVA single-phase transformer operates at 20% overload 0.80 lagging power factor. for 1hour, at
full-load 0.90 lagging power factor for 3 hours, at 50% load unity power factor for 6 hours and 10%
load 0.80 leading p.f. for the rest of the day. If the core loss is 150 watts and full-load copper loss is
500 watts,what is the B.97.7%
all-day efficiency of C.95.7%
the
D.96.7%
A.94.7%
transformer?
5. A 50 HP, 3-phase, 4-pole, 60 HZ, 230 V squirrel cage induction motor is operating full-load at
90%efficiency, 85% p.f. and 2% slip. Find the fullload torque in lb-ft.
A.184
B.418
C.149
D.194
6. Which of the following is the least efficient power plant?
A.Diesel generator set
C. Combined cycle power plant
B. Coal-fired power plant
D.Gasoline engine genset
7. A three-phase transmission line is 30 km long. The outside diameter of the conductor is 0.721 inch and
has an equilateral spacing of 4 ft. Determine the capacitance per phase of the line.
A.4.57μF
B.1.023μF
C. 0.341μF/
D.6pF
8. A sphere with positive 10 coulombs and another sphere with negative 5 coulòmbs is brought together.
What is the charge of the spheres after separation?
A.2.5/
B.7.5
C.5
D.15
9. The impedance is 5% at 120 KV, 100 MVA. What is the new percent impedance using 115 KV and 100,000
KVA as base?
A.5%
B.3%
C.4.6%
D.5.44%
10. A coil has an inductance of 12 henry. If a current of 3 amperes is discharged in 0.02 sec, what is the
induced voltage in the coil?
A.6,000
B.10,000.
C.1,800
D.15,000
11.To test the accuracy of a kilowatt-hour meter an electrician used a wattmeter. He found out that the
meter makes 5 revolutions in 18 seconds. The meter constant is 3.2. What is percentage error if the
wattmeter reading is 33687
A. 8% slower
B. 8% faster
C. 5% slower
D. 5% faster
12. The positive sequence impedance and the zero sequence impedance of transmission line is 3% and 5%,
respectively. What is the riegatie sequence impedance?
A
.
8
%
B
.
3
%
C
.
2
%
D
.
5
%
13. A 20
KV/7.87
KV
autotra
nsforme
r has a
seconda
ry line
current
of 100
A. What
is the
current
in the
commo
n
winding
?
A
.
1
3
9
.
2
5
A
B
1
0
0
A
C
.
6
0
.
6
5
A
/
D
.
3
9
.
35A
REGISTERED ELECTRICAL ENGINEERING Pre-Board Examination
Friday, August 29, 2003
8:00 a.m. - 12:00 nn.
ELECTRICAL ENGINEERING
SET A
14. Two 24-volt batteries with 0.05 Ω2 and 0.075 Ω internal resistances are connected in parallel with
a 2 Ω resistor. What is the current delivered by the 0.05 Ω battery?
A. 4.7A
B. 11.8A
C. 2.4A
D.7.1A
15. In a 34.5 KV, three- phase system, the Thevenin's equivalent impedances are:
015 p.u. at 50 MVA
𝑙1
。=0.03
Zero
𝑙=0 0.015p.u. at 50 MVA
What
is the phase-to-phase
= 0.03fault
impedance,
A. 48,000 A
Positive impedance,
B. 80,000 A
D. 32,000 A
C. 8,400 A
current?
16. A south pole 20 unit pole is placed one inch away from another south pole 35 unit pole. What is the
force between the two poles?
A. 108.5 dynes repulsion
C. 70 dynes repulsion
B. 108.5 dynes attraction
D. 70 dynes attraction
17. What is the percent slip of a 4-pole induction motor if the output speed is 1,755 rpm?
A.3
8.5
C.2.5
18. The CD-ROM drive is connected to the
A. AGP slot
B. ISA slot
D.4
of thecomputer motherboard?
C. .PCI slot
D. IDE slot
19. The phase currents of a 3ф system
are:𝑙𝑙 = 80𝑙𝑙𝑙240∘
𝑙𝑙 = 91𝑙𝑙𝑙130. 9∘ =91 cis 130.9°
What is the zero sequencecurrent?
𝑙𝑙 = 100𝑙𝑙𝑙0∘
A.0
C. 90.3 cis 123.6°
D. 26.67 cis 80°
B. 33.3 cis 0°
20. A capacitor of 8 μF capacitance is connected to a direct current source through a resistance of 1 M
Ω.Calculate the time taken by the capacitor to receive 75% of its final charge.
A. 1.109 sec
B. 9.101 sec
C. 11.09 sec
D.10.19 sec
21. A 60,000-ohm voltmeter is used to measure the insulation resistance of a motor. A 40,000-ohm
resistor is connected across the voltmeter terminals. This combination is then connected in series with
the insulation resistance and a 550-volt battery. The voltmeter deflection is 12 volts. Determine the value
of the insulation resistance.
A. 1.076 MΩ/
B. 100KΩ
C.24KΩ
D. 2.701 MΩ
22. A circuit draws a current | = 20 cos (ωt-60°A from a voltage V =240 sin wt volts. What is the power
drawn by the circuit?1 = 20cos⁡(𝑙𝑙 − 60∘ )
A. 2,30C W
B.3,984W
C.4,157 W
D. 9,200W
23.What is the size of a capacitor necessary to raise the power factor from 75% to 95% of a 3-phase motor
rated 25 HP, 440 V, 92% efficiency?
A.·10.3 KVAR
B. 10.84 KVAR
C.11.2 KVAR
D. 4.5 KVAR
24. Which of following devices will receive voltage surge first when traveling on the transmission line?
A.Lightning arresters
C. Relays
B. Step down transformers
D. Switchgears
25. How many aoC are there in one coulomb?C.10°1
A.10°
D.102
B.10°
26. A 6-pole dc generator with double layer lap winding has 20 slots per pole. How many commutator
segments does it have?
A.60
B.120
C.480
D.240
27. Three 10:1 single-phase transformers are connected wye-delta. For a primary line .voltage of
3,980volts. what is the secondary line voltage?
A. 2300V
B.3980V
C.230V-
D.398V
28. An electron of charge 1.6 x 10! C is situated in a uniform field of strength 12 x 10 volts per meter.What
is the time it takes to travel a distance of 2 cm from rest. (mass of an electron𝑙𝑙 = 9.1 × 10𝑙1 𝑙𝑙 31 kg).
⋯ 1.377 × 10.9 𝑙𝑙°sec/ B. 13.77 x 10.sec
C. 137.7x
D. 1377 x10°sec
8:00 a.m.-12:00 nn.
ELECTRICAL ENGINEERING
SET A
29. The CT ratio and PT ratio are 240 and 2000, respectively. A reactance relay is installed to protect the
line.What is the reactance of the transmission line if the reactance as seen by the reactance relay is 1.41 ohms?
A.12.252
B.0.17Ω
C.1.41Ω
D.11.75Ω
30.A hydroelectric plant has an effective head of 200 ft. The water flow is 10,000 ft3/min. The piping system
and the Pelton wheel has an overall efficiency of 75%. The generator has an efficiency of 95%. What is the
output in kW of the power plant?
A. 1112
B.2750
C.2050
D.505
31. The wires that supply.current to a 110-volt, 8 kW electric heater are 5 mm apart.What is the force per
meter between the wires?
A. 0.05 dynes
B. 2,116 dynes
C. 21,157 dynes
D. 0.2 dynes
32. A magnetic circuit consists of silicon steel 5000 permeability of 10 cm in length and cross. sectional area of
1.5 square centimeter and an air gap of the same cross-section and of 1.5 cm length. A 1.0ampere current
flows through 750 turns. What is the field intensity in the air gap?
A:628.32 Oe/
B. 6.28 Oe
C. 62.83 Oe
D. 6,283 Oe
33. The phase c line voltage and phase b line current of a balanced 3-phase system are V = 220 sin (ωot + 120
°) volts and I = 20 sin (at - 180°) amperes, respectively. What is the impedance of balanced delta connected
load?
A. 16.5-j9.53Ω
B.1616.5 + 𝑙9.53Ω
C.9.53-j5.5Ω
D.9.53+j5.5
Ω
9.53 + 𝑙5.5Ω
34. A 3-phase 22 kV, 100 MVA alternator has positive, negative and zero sequence reactances of 0.3p.u, 0.3
p.u. and 0.05 p.u., respectively. What is the negative sequence component for a line to line fault?
A.7576A
B. 4373A
C.8748 A
35. Directional relays are based on flow of C.water
A. current
D. 7345'A
D. power
B. voltage wave
36. A room measures 40 ft by 60 ft and needs 80 foot-candles of illumination. Each lamp has an output of 3,300
lumens. Depreciation and maintenance factor are 0.6 and 0.7, respectively. If each lamp consumes 53 watts,
power factor is 90%, what is the feeder current? Take supply voltage as 220volts, three-phase.
A.24
B.22
C.21
D.20
37.Which of the following equipment is used to límit short-circuit current level in a substation?
A. Isolator
B. Lighting switch
C. coupling capacitor D. series reactor
38. What is the Thevenin's equivalent reactance of a certain electric system rated 20 MVA at 34.5 KV if the
available short circuit MVA is 950?
A.1.59%
B.2.25%
C.1.75%
D.2.1%
39. A coil of 20 ohms resistance and 150 mH inductance is connected in series with a capacitor to produce
resonance. What shall be the value of the capacitor ifthe voltage is 100 sin 377t?
A. 47 μF
B.17 μF
C. 26μF
D. 86μF.
40. A 230 KV transmission line delivers a load of 100 MW at 230 KV and 85% lagging power factor.The
impedance is 5 + j12 and its capacitive reactance is 2,500 ohms. Determine the sending end line voltage.
A.230 KV
B. 239.8 KV
C. 231.8 KV
D. 234.89 KV
41. What is the rms value of a square wave with an amplitude of 10 A and frequency 1HZ?
A.0
B.10A-
C.5A
D.7.07A
42. Which of the following carries the most number of channels?D.1 fiber opticA.50 multiplexer
B. 100 pair cable
C.100 chips
8:00 a.m.-12:00 nn.
43. One watt is equal to
A. 4.19 cal/sec
C. 10'ergs/sec
B. 778 BTU/sec
D.10 ergs
REGISTERED ELECTRICAL ENGINEERING Pre-Board Examination 8:00 a.m.-12:00 nn.
Friday, August 29, 2003
ELECTRICAL ENGINEERING
SET A
44. In a certain process water is heated at a rate of 2 liters per minute. The water enters an electric heater at
25°℃ and exits at 50°C. Assuming no heat loss, calculate the wattage of the heater.
A.2420
B.3488
C.6520
D.5125
45. A space station with communication equipment that synchronizes with the earth's orbit.
A. space craft
B. space probe
C. satellite
D. space CATV
46. A dc shunt motor develops 15 HP at 120 V. The effective armature resistance is 0.061Ω. Calculate the
armature current?
A. 100 A
B.96A
C.98A
D.92A
47. A relay that opens the circuit breaker upon sensing overload.
A. Fuse
B.Differential relay C. Over current relay D. Magnetic witch
48. A 10 MVA, 13.8·KV/480 V, 5% impedance, wye -grounded delta secondary transformer serves an industrial
customer. The phase A conductor on the secondary side accidentally touches a grounded point. What is the
fault current?
A. 80,000 A
B. 120,000 A
C.50,000 A
D.0
49. In fusion energy is produced when:C. Nuclear particle divides.
.A. Fuel burns
B. Chemical compounds fused together
D. Nuclear particles combine
50. A 250 km transmission line has resistance per km of 0.05 ohm, capacitive reactance per km of 625,000 ohms
and inductive
reactance
𝑙. 12.5
+ 𝑙50 per km of 0.2 ohm. What is the series impedance of the line?
B.
37.5
C. 12.5-j2450
D. 75.5-j2450
+ 𝑙150
**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.