WorksheetsELECTRICAL ENGINEERS PRE-BOARD EXAMINATION MARCH 2018
Total questions: 38
Worksheet time: 19mins
In Delta connected circuit, when one resistor is open, then power will be
0
increased by a factor of 3
decreased by a factor of 3
remain unchanged
Which does not belong
lines per square centimeter
maxwells per square centimeter
flux
gauss
In a shunt motor, what is the relative connection of the armature winding with respect to the field winding?
series
parallel-series
series-parallel
parallel
What is considered as the most important value of a sine wave?
Effective value
Peak value
Average value
Instantaneous value
For a 3-phase load balanced condition, each phase has the same value of _
impedance
resistance
power factor
all of these
Assuming the most efficient technologies for the extraction of energy, the fuel with the largest known reserves is
Coal
Oil
Natural gas
Nuclear
A capacitive load always has a __________ power factor
Leading
Lagging
Zero
Unity
In hydro electric power plant, it is use to prevent the sudden rise and drop of water pressure
Penstock
Intake tower
Dam
Surge tank
The basis where the flow of current is from positive to negative was derived from __________
Superstition
Tradition
Scientific
Convention
By using two wattmeter method, power can be measured in
3-phase, 2-wire
3-phase, 3-wire
3-phase, 4-wire
All of these
The double energy transient occur in the
purely inductive circuit
R-L Circuit
R-C Circuit
R-L-C Circuit
Its primary source is to provide ground source
zig-zag transformer
sectionalizer
surge arrester
tertiary transformer
In a star connected system, the current flowing through the line is
Greater than the phase current
Equal to the phase current
Lesser than the phase current
None of these
Three phase induction motor is more suitable than single phase because
It’s self-starting
it has better efficiency
. it has better power factor
all of these
The luminous intensity is defined as
lumen per square meter
luminous flux per unit solid angle
illumination per square meter
candela per unit solid angle
MHO relay is used for
rectifier
circuit breaker
transmission lines
feeders
In a serious motor, what is the relation of the connection of motor field winding with the respect of the motor armature?
series
parallel
series-parallel
delta
One advantage of disturbing the winding in alternator is to
reduce harmonics
improve voltage waveform
reduce the amount of copper
decrease the value of the voltage
In dc machines, lap winding is used for
high voltage low current
low voltage low current
high voltage high current
low voltage high current
The ratio of active power to apparent power is known as
demand
load
power
form
At ________________ frequencies, the parallel R-L circuit behaves as purely resistive.
very low
low
high
very high
In a three-phase system, when the loads are perfectly balanced, the neutral current is
one-third of maximum
zero
two-thirds of maximum
at maximum
When the motor runs on no load, then
Back emf is almost equal to applied voltage
Back emf will be greater than applied voltage
Back emf will be less than applied voltage
None of these
What is the source of heat generation in cables?
Copper loss in conductor
Dielectric losses in cable insulation
Losses in metallic sheathings and armouring
All of these
The process by which a heavy nucleus is splitted into two light nuclei is known as
Splitting
Fission
Fusion
Disintegration
Efficiency of a power plant is more in summers or winters?
summers
winters
same in both
depends on variation
To reverse the direction of rotation of a three-phase induction motor, it is necessary to
interchange all the three line connections
reverse the polarity of the rotor circuit
increase the resistance of the rotor circuit
interchange any two of the three line connections
The law that induced emf and current always opposes the cause producing them was discovered by
Lenz
Maxwell
Faraday
Ohm
The power factor of an alternator is determined by its
speed
load
excitation
prime mover
In a circuit containing R, L, and C, power loss can take place in
C only
L only
R only
all of these
The efficiency of thermal power plant is approximately
10%
30%
60%
80%
The time constant of a series RC circuit is given by
R/C
RC2
RC
R 2C
A device that repeatedly reverses the polarity of a magnetic field in order to keep a dc motor rotating is known as
solenoid
armature coil
commutator
field coil
The form factor is the ratio of
peak value to r.m.s value
r.m.s value to average value
average value to r.m.s value
none of these
If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is
a sinusoidal of the same frequency
a sinusoidal of half the original frequency
a sinusoidal of double the freq
not a sinusoid
A relay is used to
receive a signal and record it
protect a circuit
connect a line to the source
relay a message to a remote place
The condition in Ohm’s law is that
ratio V/I should be constant
current should be proportional to voltage
the temperature should remain constant
the temperature should vary
How is the storage battery rated in capacity?
volts
watts
amperes
ampere-hour
