CAA Civil Aviation Authority Pakistan Assistant Director E&M Test conduct by NTS on 12‐May‐2019
The subsequent set of multiple-choice questions is extracted from the Civil Aviation Authority Assistant Director E&M Test conduct by NTS on 12‐May‐2019. These questions encompass various subjects pertinent to electrical engineering, serving as crucial preparation material for individuals aspiring to secure positions at the CAA Civil Aviation Authority Pakistan . The highlighted question statements are designed for seamless navigation, offering a thorough overview of fundamental concepts crucial for excelling in the Assistant Director E&M Test conduct by NTS on 12‐May‐2019 examination.
An Ammeter is convertible to a voltmeter by?
A) Changing the scale
B) Putting a large resistance in parallel with the actual measuring part of the instrument
C) Putting a large resistance in series with the actual measuring part of the instrument
D) Simply installing the instrument in parallel with the circuit
The residual magnetism of a dc shunt generators can be regained by
A) Connecting the shunt field to a battery
B) Running a generator on no load for sometime
C) Earthing the shunt field
D) Reversing the direction of the generator
For Parallel Operation, the generators normally preferred are?
A) Series generators
B) Shunt generators
C) Compound generators
D) Series and shunt generators
In Lap winding the number of brushes is equal to
A) 2
B) 4
C) Number of Poles
D) 2 × Number of Poles
Which of the following is not the requirement of Protection System?
A) Speed
B) Predictability
C) Reliability
D) Security
__ are used to sense the fault and initiate the trip?
A) Circuit breakers
B) Alternators
C) Protective Relays
D) Cutouts
There are two types of overload protection instantaneous over current and
A) Variable over current
B) Time Over Current
C) Constant Over Current
D) Delay feedback Current
The advantage of moving coil permanent magnet type instrument is
A) Low power consumption
B) No hysteresis loss
C) Efficient eddy current damping
D) All of the above
The deflecting torque in an instrument may be produced
A) Magnetically
B) Electrostatically
C) Thermally
D) any of the (A) (B) and (C) Above
D.C. Potentiometer is an instrument to measure
A) Unknown EMF
B) Large voltage
C) Large power
D) Direct resistance
A pointer of an instrument once deflected return to zero position, when the current is removed due
to
A) action of gravity
B) Mass of pointer
C) Controlling torque
D) Damping torques
The starting torque of a capacitor start motor is
A) Zero
B) Low
C) Same as rated torque
D) More than rated torque
A capacitor starts, capacitor run single phase induction motor is basically a
A) Ac series motor
B) Dc series motor
C) 2 phase induction motor
D) 3 phase induction motor
Copper loss in rotor of an induction motor
A) is lost in friction
B) is lost in windage
C) Appears as heat
D) Appears as noise
The difference between the synchronous speed and the actual speed of an induction motor is known
as
A) Regulation
B) Back Lash
C) Slip
D) Lag
The back emf set up in the stator of a synchronous motor will depend on
A) Rotor speed only
B) Rotor excitation only
C) Rotor excitation and rotor speed
D) Coupling angle, rotor speed and excitation
The damping winding in a synchronous motor is generally used
A) To provide starting torque only
B) To reduce noise level
C) To reduce eddy currents
D) To prevent hunting and provide the starting torque
In case the field of a synchronous motor is under excited the power factor will be
A) Leading
B) Lagging
C) zero
D) Unity
For a transformer the condition for maximum efficiency is
A) Hysteresis loss=eddy current loss
B) Core loss = Hysteresis loss
C) Copper loss = iron loss
D) Total loss = (2/3) × copper loss
What test on a transformer provides information about regulations, efficiency and heading under
load conditions?
A) Open circuit test
B) Back-to-back test
C) Hopkinson test
D) Short circuit test
Copper loss in a transformer occurs in
A) Core
B) Winding
C) Main body
D) Bushings
Open circuit test of a transformer gives
A) Hysteresis loss
B) Eddy current loss
C) Sum of hysteresis and eddy current loss
D) Copper loss
The function of breather in a transformer
A) To provide oxygen to the cooling oil
B) To provide cooling air
C) To arrest flow of moisture when outside air enters the transformer
D) To filter the transformer oil
The speed of a series-wound dc motor
A) Can be controlled by diverters
B) Cannot be controlled by diverters
C) Increases as flux decreases
D) Increases as armature circuit resistance increases
The ratio of starting torque to fully load torque is least in case of
A) Shunt motors
B) Series motors
C) Compound motors
D) None
The Speed of a dc motor is
A) Always constant
B) Inversely proportional to back E.m.f
C) Inversely proportional to flux
D) Inversely proportional to the product of back emf and flux
Each commutator segment is connected to the armature conductor by means of
A) Insulator
B) dielectric
C) Copper Lug
D) resistance wire
The rotor of Dc machines is usually supported in
A) Bush bearings
B) Ball or Roller bearings
C) Plummer Blocks
D) Magnetic bearings
Worn insulation allowing bare wires to touch grounded metal objects such as water pipes cause
A) Circuit breakage
B) Power loss
C) circuit compensation
D) short circuit
Minimum insulation required to withstand surge voltages is called,
a) Basic insulation level
b) Minimum insulation level
c) Fuse Insulation Level
3- phase, 4-wire distribution voltages may be:
A) 477/240
B) 280/220
C) 240/480
D) 208/120
In an electric power system, what is composed of electrical disconnect switches, fuses or circuit
breakers used to control, protect and isolate electrical equipment.
A. CB
B. Switchgear
C. Control box
D. Gear box
To bring down the voltage level to safe level for equipment;
A) voltage regulators
B) current regulators
C) load regulators
D) power regulators
In which transformer, connections may also be used for voltage transformation. This voltage is
further increased by the factor of 1.73
A) Delta- Delta
B) Star – Delta
C) Delta – Star
D) Star -Star
FFC 2022
A condenser in a thermal power plant condenses steam coming out of
A. Boiler
B. Super heater
C. Economizer
D. Turbine
Ans. D
The TRIAC Is a _ device with control terminal
A. Uni-directional
B. Bi-directional
C. Tri-directional
D. Two terminals
Ans. B
In a power plant, coal is carried from storage place to boilers generally by means of
A. Bucket
B. V belts
C. Trolleys
D. Manually
Ans. B
In real power system constant used a + j b, j is called
C. √1
D. √1
Ans. B
A graphical representation between discharge and time is known as
A. Monograph
B. Hectograph
C. Hectograph
D. Hydrograph
Ans. D
A tunnel diode
A. Is a highly doped P-N junction device
B. Is a gallium arsenide device
C. Is a point contact diode with a high reverse resistance
D. Has a small tunnel in its junction
Ans. A
Shunt capacitance is usually neglected in the analysis of
A. Short transmission lines
B. Medium transmission
C. Long transmission lines
D. Medium as well as long transmission lines
Ans. A
In a piston the maximum temperature occurs at
A. Ring section
B. Top sides
C. Top center
Ans. C
Which device automatically interrupts the supply in the event of surges?
- Earthing switch
- Series reactor
- Isolator
- Circuit breaker
For diesel locomotives the range of horsepower is
A. 50 to 200
B. 500 to 1000
C. 1500 to 2500
D. 3000 to 5000
Which of the following finds application in speed control of DC motor?
A. FET
B. NPN transistor
C. SCR
D. None of above
Which of the following are considered as disadvantage(s) of Gauss-Seidel method over Newton’s
method in load flow programs?
A. More iteration
B. More memory requirement and less accuracy
C. less interactions but more memory
D. More accuracy and more memory
Ans. A
The effect of wind pressure is more predominant on
A. Transmission lines
B. Neutral lines
C. Insulator
D. Supporting towers
Ans. D
For constant voltage transmission, voltage drop is compensated by installing
A. Synchronous motors
B. Inductors
C. Capacitors
D. All of above
Ans. A
Out of following which one is not an unconventional source of energy
A. Tidal power
B. Geothermal energy
C. Nuclear energy
D. Wind power
Ans. C
In a hydro-electric plant a conduit system for taking water from the intake works to the turbine is
known as
A. Dam
B. Reservoir
C. Penstock
D. surge tank
Ans. C
Which type of engine uses maximum air fuel ratio?
A. Petrol engine
B. Gas engine
C. Diesel engine
D. Gas turbine
Ans. D
Unit of electric charge
Coulomb
Ampere
Candela
Mol
In outdoor substation the lightning arresters are placed nearer to
A. Isolator
B. Current transformer
C. Power transformer
D. Circuit breaker
Ans. C
The large or surge impedance loading of a long transmission line can be increased without
adversely affecting its stability by connecting a lumped
A. Inductance in series with the line
B. Inductance in shunt with the line
C. Capacitance in shunt with the line
D. Capacitance in series with the line
Ans. D
Discrete device field effect transistor is classified on the basis of the
A. Resistive state
B. Conducting state
C. Voltaic state
D. Control gate construction
Ans. D
Which of the following type tests are conducted on isolators?
(A) Temperature rise test
(B) Impulse stage with stand test
(C) Short time current test
(D) All of the above.
Which type of copper wire will have the highest tensile strength?
A. Soft drawn
B. Medium drawn
C. Hard drawn
D. None
Ans. C
Which of the following is NOT a purpose of Disturbance Monitoring?
A. Model validation
B. Disturbance investigation
C. incorrect relay setting
D. Assessment of system protection performance
Ans. C
The EM field and current are concentrated close to the surface of conductor. The phenomenon is
called
A. Skin effect
B. Faraday effect
C. EM concentration effect
D. Ohm’s effect
Ans. A
In DC choppers per unit ripple is maximum when duty cycle alpha (a) is
A. 0.1
B. 0.3
C. 0.5
D. 0.7
Ans. C
Which distribution system is more reliable?
A. Ring main system
B. Tree system
C. Radial system
D. All are equally reliable
Ans. A
If the firing angle in an SCR rectifier is decreased, output will be
A. Maximum
B. Increased
C. Decreased
D. Unaffected
Ans. B
In a transmission line following are the distributed constants
A. Resistance and inductance only
B. Resistance, inductance and capacitance
C. Resistance, inductance, capacitance and short conductance
D. None of above
Ans. C
The principal of ………… can be used to analyze faults in power systems?
A) Thevenin
B) Norton
C) Superposition
D) Jordon
If 3000 kW power is to be transmitted over a distance of 30 km what will be the voltage level to
transmit the power?
A. 11kV
B. 33 kV
C. 66 kV
D. 132 kV
Ans. B
For which purpose bundled conductors are employed to a power system
A. Appearance of the transmission line
B. Mechanical stability of line
C. Decrease system stability
D. Increase the short circuit current
Ans. D
In large power transformer, best utilization of available core space can be made by employing
_ cross section. A. Rectangular B. Square C. Stepped D. None of above SCR (Silicon controlled rectifier) goes into saturation, when gate-cathode junction is A. Forward biased B. Reverse biased C. In steady state D. Polarized Ans. A To improve the efficiency of thermal power plant ________ is placed between boiler and
turbine.
- ash handling point.
- air preheater.
- economizer.
- superheater.
D.C. generator generates
A. a.c. voltage in the armature
B. d.c. voltage in the armature
C. a.c. superimposed over d.c.
D. none of the above
Which of the following enters the super heater of a boiler?
A. Cold steam
B. Hot water
C. Wet steam
D. superheated steam
Ans. C
Why regenerator use in gas turbine power plant? - To produce extra heat
- To produce high pressure in the chamber
- To produce a high temperature
- To recover heat from exhaust gases
A relay used on long transmission lines is
A. Mho’s relay
B. Reactance relay
C. Impedance relay
D. No relay is used
Ans. A
Which variety of coal has lowest calorific value?
A. Steam coal
B. Bituminous coal
C. lignite
D. Anthracite
Ans. C
Hydrogen is used for cooling of large sized generators because
A. It has high thermal conductivity
B. It is light
C. It offers reduced fire risk
D. All of above
Ans. D
The current drawn by line due to corona losses is
A. Sinusoidal
B. Square
C. Non-sinusoidal
D. None of above
Ans. C
A transformer has negative voltage regulation when its load power factor
A. Zero
B. Unity
C. Leading
D. Lagging
Ans. C
Drop out to cutoff ratio for most relays is of the order of
a) 0.2 to 0.3
b) 0.3 to 0.4
c) 0.4 to 0.6
d) 0.6 to 1.0
As compared to oscillators, inverter provides
A. Low voltage output
B. Low frequency output
C. Distortion less output
D. Noise less output
Ans. B
Which of the following is not the transmission voltage level?
66 kV
132 kV
264 kV
400 kV
When the secondary of the transformer is loaded, the primary current will
A. not be affected
B. increase
C. be less than the secondary current
D. be the vector sum of no-load current and additional current drawn due to the secondary
current
Alternating current power is transmitted at high voltage
(A) to safeguard against pilferage
(B) to minimize transmission losses
(C) to reduce cost of generation
(D) to make the system reliable
The function of a regenerator in a gas turbine is to
reduce heat loss in exhaust
permit use of higher compression ratio
improve thermal efficiency
None of these
j will force the phasor to rotate through a fixed angle of
1) 90o in an anticlockwise direction
2) 90o in a clockwise direction
3) 180o in an anticlockwise direction
4) 180o in a clockwise direction
What is the superior quality of coal called?
A. Anthracite
B. Coke
C. Bituminous
D. Peat
Disclaimer
“The information presented in this blog post has been compiled from various engineering professionals’ accounts on social media platforms. It is intended for informational purposes only and does not necessarily represent official statements or policies of the individuals or organizations mentioned. Readers are encouraged to verify and cross-reference information independently.”
