WorksheetsEE 1-1
Total questions: 50
Worksheet time: 25mins
In how many years will the energy consumption of the Philippines be quadrupled at 6.9% annual growth rate?
5
10
15
20
What does ACSR conductor stand for?
All Conductors Surface treated and Realigned
Aluminum Cable Steel Reinforced
Anodized Core Steel Reinforced
Aluminum Cable Stranded Reinforced
Two resistors R1 and R2 are connected in parallel. R1 is twice of R2. If the current in R1 is I, what is the current in R2?
I
2I
4I
I/2
The rotor of a 3-phase, 60-Hz, 4-pole induction motor takes 120 kW at slip frequency of 3 Hz. Determine the rotor speed.
1674 rpm
1728 rpm
1710 rpm
1692 rpm
The resistance of the rod does NOT depend on:
its temperature
its material
its length
the shape of its (fixed) cross-sectional area
A certain galvanometer has a resistance of 100 Ω and required 1 mA for full scale deflection. To make this into a voltmeter reading 1 V full scale, connect a resistance of:
1000 Ω in parallel
900 Ω in series
1000 Ω in series
10 Ω in parallel
The electrical analog of a spring constant k is:
L
1/L
C
1/C
If |Vsl| = |Vsl| = 33 kV (three-phase) and X = 13 ohm per phase, what will be the maximum power transmission per phase?
29 MW
30 MW
60 MW
28 MW
A delta 3φ, 4-wire secondary 240/120 V would have a high leg to neutral voltage of
208 V
240 V
277 V
199 V
Which transformer has only one winding?
distribution transformer
power transformer
autotransformer
isolated winding transformer
A multimeter is connected to one terminal of primary and the other terminal of secondary to measure resistance. The multimeter reading would be
infinity
zero
equal to resistance of the windings
zero or infinity
Amplitude modulation generated at a very low voltage or power amplitude is known as
high-level modulation
low-level modulation
collector modulation
minimum modulation
The current in a 4-H inductor decreases uniformly from 30 A to 10 A in 0.2 s. What is the inductor voltage for this time?
100 V
200 V
300 V
400 V
A washing machine is, in effect, an R-L circuit. If the machine takes 311 W and 4.5 A from a 155-V source when operating normally. Find its power factor.
0.70 lagging
0.80 lagging
0.75 lagging
0.60 lagging
For an unbalanced load, which connection is suitable?
3-wire open delta
4-wire wye connection
3-wire delta connection
3-wire wye connection
Approximately how far away must an isolated positive point charge of 1 x 10^-8 C be in order for it to produce an electric potential of 100 V? The charge is in free space with ε0 = 8.85 × 10^-12 C²/N·m².
0.90 m
1.2 m
5.3 m
8.6 m
The effect of electric shock in the human body will depend on
line voltage
line current
current flowing in the body
none of these
In two-wattmeter method, the readings of the wattmeters will be identical when
load in one of the phases is zero
power factor is unity
power factor is 0.5
neutral is earthed
The function of a surge tank is
to supply water at constant pressure
to produce surges in the pipe line
to relieve water hammer pressures in the penstock pipe
to relieve surge on the boiler
Two capacitors having capacitances C1 = 8 μF and C2 = 4 μF are connected in series with a source of potential difference Vab = 12 V. Find the potential difference across the 8 μF capacitor.
8
4
2
1
A 15-ohm resistor is connected in parallel with a series combination of resistors of 8 and 12 ohms. If the drop across the 8-ohm resistor is 48 volts, determine the total current.
18
16
12
14
For measuring current at high frequency, we should use
dynamometer
oscilloscope
thermocouple
moving iron instrument
A loop of wire carrying a current of 2.0 A is in the shape of a right triangle with two equal sides, each 15 cm long. A 0.7 T uniform magnetic field is parallel to the hypothenuse. The resultant magnetic force on the two equal sides has a magnitude of
0
0.21 N
0.41 N
0.51 N
The tesla is a unit of
permittivity
capacitance
inductance
magnetic flux density
A symmetrical three-phase 240 V supplies a balanced delta connected load of 6 - j8 ohms per phase. What is the line current?
-25 + j32 A
25 - j5.78 A
-25 - j32 A
25 + j32 A
A room 8 m x 12 m is lighted by 15 lamps to fairly uniform illumination of 100 lumens per square meter. What is the coefficient of utilization if the output of each lamp is 1,600 lumens?
40%
30%
60%
50%
The winding of a 4-pole alternator having 36 slots and a coil span of 1 to 8 is short-pitched by ____ degrees.
140
80
20
40
Which is the most suitable for punch presses?
shunt motor
differentially compounded motor
series motor
cumulatively compounded motor
Transient response in the system is basically due to
Forces
Friction
Stored Energy
Coupling
A series RL circuit has R = 6 Ω and Xl = 8 Ω. What is the circuit conductance?
0.06 mho
0.17 mho
0.08 mho
0.125 mho
Conventional or VRE Embedded Generating Plants with Installed Capacity larger than 100 kW and equal to or less than 1 MW.
Large VRE
Medium
Intermediate
Small
A 3-phase, 22 kV, 100 MVA alternator has positive, negative and zero sequence reactances of 0.3 p.u, 0.3 p.u and 0.05 p.u, respectively. What is the negative sequence component for a line to line fault?
7,345 A
7,576 A
8,748 A
4,373 A
In a 12-pole duplex lap wound dc armature, each conductor can carry a current of 20 A. If there are a total of 480 conductors, what is the rated current of the armature?
480 A
9,600 A
400 A
960 A
A circuit consisting of a coil of inductance 10 mH and resistance 300 Ω connected in parallel with a certain capacitor resonates at 48 KHz. What is the size of this capacitor in picofarads?
910
9,100
1,090
109
The resistance of shunt windings of a dc generator before and after a long run is 55 Ω and 65 Ω, respectively. If for copper α = 0.0042/°C, find the temperature rise of the windings.
24°C
23.6°C
25°C
42.5°C
Which of the following will need the lowest level of illumination?
Displays
Fine engraving
Railway platform
Auditoriums
An electric 9 kW range shall have a minimum branch circuit size of which of the following:
15 amps
20 amps
30 amps
40 amps
A 20 hp, 440 V, 60 Hz, 4-pole, 3-phase induction motor has 5% slip at full-load. The mechanical rotational losses are 400 watts. Calculate the full-load rotor copper loss in watts.
695
740
782
806
What classification is given to a d.c. generator that receives its field excitation current from internal source?
self excited
controlled excitation
separately excited
internally excited
What is the power required to transfer 97,000 coulombs of charge through a potential rise of 50 volts in one hour?
0.5 kW
0.9 kW
1.3 kW
2.8 kW
Conductors supplying two or more motors shall have an ampacity equal to the sum of the following current rating of all the motors plus ___ % of the highest rated motor in the group.
25
80
100
125
Two (2), 1φ, 100-KVA transformers are connected in V (open delta) bank supplying a balanced 3φ load. If the balanced 3φ load is 135 kW at 0.82 p.f. lagging and 0.823 efficiency, determine the overload KVA of the open delta bank.
15.5
26.8
31
8.9
Induction generators deliver power at
Leading power factor only
Lagging power factor only
Leading as well as lagging power factor
Unity power factor only
A 240 V dc series motor develops a shaft torque of 200 N·m at 92% efficiency while running at 600 rpm. Calculate the motor current.
62.09 A
52.36 A
48.17 A
56.91 A
An electric heater takes 23.889 kCal in 20 min at 200 volts. What is the current drawn by the heater?
8.4 A
16.67 A
1.67 A
0.42 A
A single-phase, 10-km transmission line has 16.65 mH total inductance. If the distance between the conductors is 1 m, what is the conductor radius?
1 cm
2 cm
1.5 cm
2.5 cm
This is an electrically operated switch which is rated in amperes and is also used in overload protection of motors.
magnetic starter
safety switch
magnetic contactor
manual starter
The power input to a three-phase, 5,000 kVA, 6,600-volt synchronous condenser is 160 kW. Its power output is ____.
160 kW
150 kW
100 kW
0
In an unbalanced wye connected system
Ia = 10 cis (-32°)
Ib = 13 cis (212°)
Ic = 14 cis (86°)
What is the neutral current?
2.37 cis 131.4 deg
0.79 cis 43.8 deg
7.11 cis 79.4 deg
37 cis 266 deg
A 2-henry inductor has 120 turns. How many turns must be added to raise its inductance to 3 henry?
147 turns
180 turns
27 turns
60 turns
