ELECTRICAL ENGINEERING (PROF COURSE)

A/An ________ relay that operates or pick-up when its current exceeds a pre-determined value.

A. directional

B. overcurrent

C. directional voltage

D. overvoltage

overcurrent

Nine identical wires, each of diameter d and length L, are connected in parallel. The combination has the same resistance as a single similar wire of length L but whose diameter is:

A. 3d

B. 9d

C. d/3

D. d/9

3d

In which type of electronic communications does the information travel in two directions?

A. Half duplex

B. Full duplex

C. Multiplex

D. Bicomm

Full duplex

In power station practice “ spinning reserve “ is

A. reserve generating capacity that is in operation but not in service

B. reserve generating capacity that is connected to bus and ready to take the load

C. reserve generating capacity that is available for service but not in operation

D. capacity of the part of the plant that remains under maintenance

reserve generating capacity that is connected to bus and ready to take the load

Which of the following type of fault used only the equivalent positive sequence impedance of the circuit in the short-circuit calculation?

A. Line to line

B. Line to ground

C. Double line to ground

D. Three-phase fault

Three-phase fault

Minimum height of service drop conductors over tracks of railroad is __________ mm.

A. 3700 mm

B. 4500 mm

C. 5500 mm

D. 7500 mm

7500 mm

Heating effect of current has an undesirable side effect in

A. electric oven

B. immersion heater

C. electric iron

D. vacuum cleaner

vacuum cleaner

The standard practice nowadays in alternators is to have

A. rotating field

B. rotating armature

C. both rotating field and rotating armature

D. neither rotating field nor rotating armature

rotating field

A control system in which the control action is somehow dependent on the output is known as _____

A. closed loop system

B. semi closed loop system

C. open system

D. none of these

closed loop system

Strength of an electromagnet can be increased by

A. all of these

B. increasing the number of turns

C. increasing the current supply

D. increasing the cross-sectional area

all of these

Synchronous motor is capable of being operated at

A. lagging power factor only

B. leading power factor

C. lagging and leading factor

D. none of these

lagging and leading factor

Analysis of control systems by Laplace transform technique is not possible for

A. discrete-time systems

B. linear system

C. time-invariant systems

D. unstable continuous-time systems

discrete-time systems

Lux is the unit of which of the following?

A. Wavelength

B. Luminous intensity

C. Luminous flux

D. Illumination

Illumination

An instrument which detects electric current is known as

A. voltmeter

B. rheostat

C. wattmeter

D. galvanometer

galvanometer

For an LC parallel circuit at resonance, all the statements given below are correct EXCEPT:

A. the line current is maximum at resonance

B. the branch currents at resonance are equal

C. The angle between branch currents is 180 degree at resonance

D. the admittance is minimum at resonance

the line current is maximum at resonance

For a 3-phase unbalanced load

A. the power factor of each phase will be in proportional to the load.

B. the power factor of each phase will be the same

C. the power factor of at least one of the phase must be leading

D. the power factor of each phase may be different

the power factor of each phase may be different

Which DC motor can be used as a series, shunt and compound motor

A. series

B. shunt

C. compound

D. universal

compound

In two wattmeter method, the reading of one of the wattmeter will be zero when

A. power factor is unity

B. power factor is 0.5

C. load in one of the phases is zero

D. a neutral wire in not provided

power factor is 0.5

In an alternator, the armature reaction is mainly influenced by

A. the power factor of the load

B. short-circuit ratio

C. speed of the alternator

D. total current draw

the power factor of the load

In an actual transformer, the iron loss remains practically constant from no-load to full-load because

A. value of transformation ration remains constant

B. permeability of transformer remains constant

C. core flux remains practically constant

D. primary voltage remains constant

core flux remains practically constant

The double cage rotors are used to

A. increase pull out torque

B. increase starting torque

C. improve efficiency

D. reduce rotor core losses

increase starting torque

In a rectifier, the larger the value of shunt capacitor filter

A. larger the peak-to-peak value of ripple voltage

B. larger the peak current in rectifying the diode

C. longer the time that current pulse flows through the diode

D. smaller the DC voltage across the load

larger the peak current in rectifying the diode

The real part of propagation constant of a transmission line is

A. phase constant

B. attenuation constant

C. stability constant

D. reliability factor

attenuation constant

_________ can generate power at unpredictable or uncontrolled times.

A. Solar power plant

B. Tidal power plant

C. Wind power plant

D. Any of these

Any of these

Entrances to rooms and other guarded locations containing exposed live parts shall be marked with _______ warning signs forbidding unqualified persons to enter.

A. yellow

B. blue

C. conspicuous

D. orange

conspicuous

The type of SF₆ power circuit breaker that is standard with ANSI

A. sealed tank

B. dead tank

C. live tank

D. pull tank

dead tank

A hydro power plant of run-off river type should be provided with a pondage so that the

A. firm-capacity of the plant is increased

B. operating head is controlled

C. kinetic energy of the running water is fully utilized

D. pressure inside the turbine casing remains constant

firm-capacity of the plant is increased

The positive sequence component of voltage at the point of fault is zero when it is a:

A. 3-phase fault

B. L-L fault

C. L-L-G fault

D. L-G fault

3-phase fault

What is the function of thermistor?

A. To measure temperature

B. To measure pressure

C. To measure flow

D. To measure level

To measure temperature

86 is the device function number assigned by NEMA and IEC to this protective relay.

A. Differential

B. Frequency

C. Lock out

D. Over voltage

Lock out

The greater the size of room, the coefficient of utilization will be _________

A. higher

B. lower

C. unchanged

D. unpredictable

higher

What is the algebraic sum of the reference input and feedback?

A. error signal

B. error detector

C. controlled system

D. controlled output

error signal

Two holes in the disc of energy meter are drilled at the opposite sides of the spindle to

A. improve its ventilation

B. eliminate creeping at no load

C. increase its deflecting torque

D. increasing its braking torque

eliminate creeping at no load

An electron volt is:

A. the force acting on an electron in a field of 1 N/C

B. the energy gained by an electron in moving through a potential difference of 1 volt

C. the energy needed to move an electron through a potential difference of 1 volt

D. the work done when 1 coulomb of charge is moved through a potential difference of 1 volt

the energy gained by an electron in moving through a potential difference of 1 volt

As compared to the closed loop system, an open loop is

A. more stable but less accurate

B. less stable as well as less accurate

C. more stable as well as more accurate

D. less stable but more accurate

more stable but less accurate

The root locus technique in control system was first introduced in the year 1948 by _______

A. John Locus

B. Walter Evans

C. Joseph Root

D. Walter Root

Walter Evans

FDLF method is suitable for

A. high voltage transmission system

B. medium voltage transmission system

C. distribution system

D. none of these

high voltage transmission system

Corona loss can be reduced by the use of hollow conductor because

A. the current density is reduced

B. eddy current in the conductor is eliminated

C. for a given cross-section, the radius of the conductor is increased

D. of better ventilation in the conductor

for a given cross-section, the radius of the conductor is increased

In a series RLC circuit, the current at resonance is ____________.

A. zero

B. maximum

C. minimum

D. infinity

maximum

The specific resistance p in defined as

A. resistance of a any conductor at 20 degree C

B. resistance of a conductor has a length of 1 m and cross-section of 1m² at 25 degree C

C. resistance of a any conductor at 25 degree C

D. resistance of a conductor has a length of 1m and cross-section of 1m^{3 at 20 degree C}

resistance of a conductor has a length of 1 m and cross-section of 1m² at 25 degree C

Which of the following defined the Fermi Energy?

A. The amount of energy which a valence electron can have at room temperature

B. The amount of energy which a hole can have at room temperature

C. The amount of energy which must be given to an electron to move it to conductor

D. the amount of energy which must be given to hole it in valence band

The amount of energy which must be given to an electron to move it to conductor

Gauss-Seidel method is used for

A. Linear algebraic equations only

B. Linear differential equations only

C. Both linear and nonlinear algebraic equations

D. Both linear and nonlinear algebraic equations

Linear algebraic equations only

Rapid stopping of a motor by momentarily connecting the motor in reverse direction

A. Plugging

B. Jogging

C. Inching

D. Sequence operation

Plugging

Which of the following power plant is a non-renewable energy?

A. Wind energy

B. Nuclear energy

C. Geothermal energy

D. Solar energy

Nuclear energy

Under voltage relay are mostly used for

A. Transformer protection

B. Busy bar protection

C. Motor protection

D. Feeder protection

Motor protection

It is a disruptive discharge between electrodes of a measuring gap, voltage control gap, or protective device

A. Flashover

B. Sparkover

C. Corona

D. Fireover

Sparkover

The reactance of a rotating machine that determines the current that circuit breakers will have to open to clear a fault or short-circuit is

A. subtransient

B. synchronous

C. transient

D. Steady state

transient

Which of the following type of fault that used only the equivalent positive impedance of the circuit in the short-circuit calculation?

A. Three-phase fault

B. Line-to-Line fault

C. Single-line

D. Double-line-to-ground fault

Three-phase fault

The rotation of a direct current motor may be reversed by

A. reversing the line connection to the motor

B. reversing either the armature or field

C. reversing both the armature and field connection

D. shifting the brushes opposite to the direction in which the motor is rotating

reversing either the armature or field

What is the device used to a generator to prevent motorizing?
A. Directional-current relay

B. Overvoltage relay

C. Over frequency relay

D. Reverse Power Relay

Reverse Power Relay

The size of a conductor used in power cables depends on the

A. operating voltage

B. power factor

C. current to be carried

D. type of insulation used

current to be carried

As compared to /\ - /\ bank, the capacity of the V - V bank of transformers is ______ percent.

A. 57.7

B. 66.7

C. 50

D. 86.6

57.7

Cellular phones operate in the frequency range of

A. EHF

B. VHF

C. UHF

D. SHF

UHF

For synchronous motor, over excited is ________

leading

For synchronous motor, under excited is ________

lagging

DC Rotating Relay

82

AC Circuit Breaker

52

Voltage and Power

92

Find the geometric mean radius of a conductors in vacuum and separated 1 meter between centers when a current of 1 ampere flows through each conductor, produce on each other a force of

A. 2 × 10^{-2 N/m}

B. 2 ×10^-3 N/m

C. 2 × 10 ^-5 N/m

D. 2 × 10 ^-7 N/m

2 × 10 ^-7 N/m

In the field of a synchronous motor is under-excited the power factor will be

A. lagging

B. leading

C, unity

D. more than

lagging

In DC machines, lap winding is used for

A. high voltage, low current

B. low voltage, low current

C. high voltage, low current

D. low voltage, high current

low voltage, high current