SET C (EE) Flashcards
What is the function of the surge tank in the hydropower plant?
A. Relieve water hammer pressures in the penstock pipe
B. produce surge in the pipe line
C. Relieve water pressure in the boiler
D. supply water at constant pressure
Relieve water hammer pressures in the penstock pipe
The resistance of resistor 1 is twice of resistor 2. The two are connected in SERIES and a potential difference is maintained across the combination. What is the rate of thermal energy generation in resistor 1?
A. Twice that in resistor 2
B. Half that in resistor 2
C. Four times that in resistor 2
D. The same as that in resistor 2
Twice that in resistor 2
The hazards exists only during the period of time the ________ is there.
A. short-circuit
B. switching
C. lightning
D. fault
fault
Which of the following is NOT a reason why single-phase induction motor run?
A. two windings are displaced from each other
B. hysteresis
C. one of the current is made out of phase between the lines
D. shaded poles
hysteresis
Which of these is NOT a simplex type of electronic communications?
A. TV broadcasting
B. Facsimile or fax
C. Paging services
D. Telephone
Telephone
A good example of kinetic energy is provided by ________.
A. a tornado
B. a wound clock spring
C. an automobile storage battery
D. the raised weights of a grandfather’s clock
a tornado
What size of branch circuit is required for a window air conditioner with a nameplate rating of 8-A if the circuit also supplies other outlets?
A. 17 A
B. 25 A
C. 20 A
D. 15 A
If the aircon is in an individual branch circuit, the multiplier is 1.25
But if the aircon is in a multiple branch circuit, the multiplier is 2
so the answer is 20 A
Which of the following is NOT INCLUDED in the Technical Performance Standards for Distribution and Supply set by the Philippine Distribution Code?
A. Power Quality
B. Reliability
C. Collection Efficiency
D. System Efficiency
Collection Efficiency
For constant transmission efficiency, voltage is increased n times, the size of the conductor would be _______.
A. reduced to (1/n) times of the original
B. reduced to (1/n²) times of the original
C. increased to n² times of the original
D. increased to n times of the original
reduced to (1/n²) times of the original
Which of these is not a factor in the selection of fuse rating for protection of a branch circuit?
A. Branch full-load current
B. System Impedance
C. Branch fault-current
D. System voltage
System Impedance
A transformer has a reactance of 0.04 per unit. What will be the symmetrical short circuit current will be if the secondary of the transformer is short-circuited with nominal voltage applied to the primary?
A. 16 times of the full load current
B. 4 times of the full load current
C. 25 times of the full load current
D. 5 times of the full load current
25 times of the full load current
The electron is a/an ______ charged particle of electricity.
A. neutral
B. negatively
C. positively
D. zero
negatively
According to Philippine Electrical Code at an ambient temperature of 30°C, 8.0 mm² copper conductors with the following insulation have the following ampacities: TW insulation = 30 A; THW insulation = 45 A; for THHN insulation = 50 A. If each of these insulated wires carries the same 40 Amp which will generate heat the fastest?
A. THW insulated wire
B. Each will generate same heat
C. THHN insulated wire
D. TW insulated wire
TW insulated wire
Which of the following effects are generally less for an alternating current than for a direct current?
A. heating effects
B. chemical effects
C. magnetic effects
D. impedance
chemical effects
What is/are the main reason/s for using high voltage in transmission of power in the grid system?
I. to transmit bulk power with minimum line losses
II. increase system reliability
A. II only
B. both I and II
C. either I or II
D. I only
I only
A device used to measure the impurities in the insulating oil is a/an
A. Megger
B. Hipot
C. Oil tester
D. Surge tester
Oil tester
For an unbalanced load, which connection is suitable?
A. 3-wire open delta
B. 4-wire wye connection
C. 3-wire delta connection
D. 3-wire wye connection
4-wire wye connection
Its primary function is to provide ground source.
A. zig-zag transformer
B. sectionalizer
C. surge arrester
D. tertiary transformer
zig-zag transformer or grounding transformer
The amount of frequency deviation from the carrier center of frequency in an FM transmitter is proportional to the ______.
A. shape
B. amplitude
C. frequency
D. phase
amplitude
What kind of load an alternator has for a negative voltage regulation?
A. Resistive
B. Inductive
C. both A and B
D. Capacitive
Capacitive
The strain type insulators are used when
I. Transmission line is dead ended
II. The direction of the transmission line changes
A. I only
B. II only
C. Either I or II
D. Neither I or II
Either I or II
The law that induces emf and current always opposes the cause producing them was discovered by
A. Faraday
B. Maxwell
C. Lenz
D. Ohm
Lenz
What is the main use of zigzag transformer?
A. To step down voltage
B. To step down current
C. To stabilize transformer sequence currents
D. To provide path to zero sequence currents
To provide path to zero sequence currents
If the height of the transmission tower is decreased, the capacitance of the line
A. increases
B. decreases
C. none of these
D. remains the same
increases
Ohm’s law does not apply to
A. conductors
B. conductors with change in temp
C. semiconductor
D. ac circuit
semiconductor
In tap-changing transformer, taps are usually provided on
A. HV side
B. LV side
C. any side
D. both sides
HV side
If for current, it is low voltage side because the current is very low high voltages
In a circuit breaker, the time duration from the instant of the fault to the extinction of arc is known as
A. operating time
B. lead time
C. lag time
D. total clearing time
total clearing time
The color reserved for use in equipment grounding conductor is
A. Yellow
B. Green
C. White
D. Gray
Green
for White, it is used for grounded and neutral wires
34.5 kV to 69 kV is classified as
A. low voltage
B. medium voltage
C. high voltage
D. extra high voltage
high voltage
Note these
LV = 1,000 V and below
MV = 1,000 V to 34.5 kV
HV = 34.5 kV to 230 kV
EHV = 230 kV to 800 kV
UHV = 800 kV and above
In a given circuit when power factor is unity the reactive power is
A. maximum
B. equal to I²R
C. zero
D. minimum
zero
The curve representing Ohm’s law is
A. a parabola
B. linear
C. a sine function
D. a hyperbola
linear
The condition in Ohm’s law is that
A. ratio V/I should be constant
B. I should be proportional to V
C. the temperature should remain constant
D. the temperature should vary
the temperature should remain constant
To adjust the power of an alternator, adjust the
A. power factor
B. governor
C. field current
D. frequency
governor
In a shunt generator, the voltage builds up until constrained by
A. armature heating
B. insulation restrictions
C. speed limitation
D. saturation of iron
saturation of iron
The dc armature winding in which the coil sides are placed a pole pitch apart is a
A. fractional pitch
B. full pitch
C. pole pitch
D. multiplex
full pitch
If less than a pole pitch apart, the answer is fractional pitch
The reciprocal of permeability
A. susceptibility
B. permittivity
C. conductivity
D. reluctivity
reluctivity
In the left hand rule, thumb always represents direction of the
A. current
B. voltage
C. magnetic field
D. force on the conductor
force on the conductor
In transmission systems, the weight of the copper conductor is proportional to
A. 1/E^2
B. E
C. E^2
D. 1/E
1/E^2
this is also the same in 1/X^2
What kind of device is a diode?
A. Linear
B. Non-linear
C. Unipolar
D. Bilateral
Non-linear
The maximum efficiency of a half-wave rectifier circuit is
A. 80.6%
B. 40.1%
C. 20.3%
D. 50%
40.1%
4/pi^2
for full wave: 8/pi^2
It is difficult to magnetize steel because of its
A. high density
B. high retentivity
C. low permeability
D. high permeability
low permeability
_______ is the overall energy program formulated and updated yearly by the DOE submitted to the Congress pursuant to RA 7638
A. Philippine Energization Program
B. Philippine Energy Plan
C. Philippine Electrification Program
D. Philippine Electrification Plan
Philippine Energy Plan
Which of the following is not a full duplex?
A. telemetry
B. telephone
C. LAN
D. radar
radar
Present day capacitors which have a high capacitance in small size uses a dielectric of
A. rubber
B. paper
C. ceramic
D. mylar
ceramic
The torque angle δ continuously increases, system will become
A. stable
B. unstable
C. oscillatory
D. asymptomatic
unstable
Zero-sequence current can flow from line to transformer banks in ________ connection.
A. delta/star
B. delta/delta
C. Y/grounded Y
D. grounded star/delta
Grounded star/delta
Combined cycle powerplant is used for
A. base load
B. peak load
C. none of these
D. both base and peak load
both base and peak load
Compared to Gauss-Seidel, Newton-Raphson method takes
A. Less number of iterations and more time per iteration
B. Less number of iterations and less time per iteration
C. More number of iterations and more time per iteration
D. more number of iterations and less time per iteration
Less number of iterations and more time per iteration
Gauss-Seidel iterative method can be used for solving a set of
A. Linear differential equations only
B. Linear algebraic equations only
C. Both linear and nonlinear algebraic equations
D. Both linear and nonlinear algebraic differential equations
Linear algebraic equations only
A 15-bus system with 3 voltage-controlled bus will have a Jacobian matrix of size
A. 12 x 12
B. 25 x 25
C. 11 x 11
D. 24 x 24
solution:
2n - 2 - m
2(15) - 2 - 3 = 25
Answer: 25 x 25
Two wired made of the same material have the same lengths but different diameters. They are connected in SERIES to a battery. Which of the following quantity is the same for the two wires?
A. current
B. current density
C. voltage
D. end-to-end potential difference
current
Which of the following instruments is suited for high frequency measurements?
A. Dynamometer
B. Oscilloscope
C. Moving iron vane
D. Thermocouple
Thermocouple
At a certain location in Australia, it is necessary to supply 300 kW of 60 Hz power. The only power sources available operate at 50 Hz. It is decided to generate the power by means of a motor-generator set consisting of a synchronous generator. How many poles should each of the two machines in order to convert 50 Hz to 60 Hz power?
A. A 10-pole synchronous motor coupled to a 10-pole synchronous generator.
B. A 12-pole synchronous motor coupled to a 12-pole synchronous generator.
C. A 12-pole synchronous motor coupled to a 10-pole synchronous generator.
D. A 10-pole synchronous motor coupled to a 12-pole synchronous generator.
A 10-pole synchronous motor coupled to a 12-pole synchronous generator.
Which of the following limits the number of coils that may be placed on the armature of a DC motor or generator?
A. coil to coil arcing due to the breakdown of insulation
B. the sizes of the load on the motor
C. the type of winding used
D. the number of poles
coil to coil arcing due to the breakdown of insulation
