NPCIL 2019 Exam paper SA/ST CAT-I (Electrical)

Question No. 1

The maximum temperature permitted in Class A insulation is

A) 180° C             B) 155° C

C) 120° C             D) 105° C

 Answer Key: D

Question No. 2

MHCP in illumination stands for

A) Median Horizontal Candle Power                B) Mode Horizontal Candle Power

C) Mean Horizontal Candle Power                   D) Meridian Horizontal Candle Power

Answer Key: C

Question No. 3

___________ states that a current will be induced in a conductor which is exposed to a changing magnetic field.

A) Faraday’s law                    B) Lenz’s law

C) Gauss’s law                      D) Maxwell’s law

Answer Key: A

Question No. 4

A Cathode Ray Oscilloscope gives __________ representation of the time varying signals.

 A) Actual             B) Approximate

C) Visual               D) Incorrect

Answer Key: C

Question No. 5

________ Type of lamp holder is fitted directly on the wooden board, which itself is fixed on the wall

A) Bracket           B) Angle

C) Pendant                    D) Batten

Answer Key: D

Question No. 6

Which of the following is/are the advantages of the parallel operation of an alternator?

A) Load supply can be increased            B) High efficiency

C) Operating cost is less                         D) All of the options

Answer Key: D

Question No. 7

A circuit that contains a pure resistance connected in series with a coil having pure inductance is known as

A) RLC series circuit                         B) RL series circuit

C) RC series circuit                           D) LC series circuit

Answer Key: B

Question No. 8

If three resistors of equal resistances (R) are connected in series, then the equivalent resistance will be

A) 3R                                 B) 1R

 C) 0.666 R                        D) 0.333 R

 Answer Key: A

Question No. 9

Which of the following features of an induction motor helps in preventing cogging of the motor?

A) High slip                    B) Large number of poles

C) Use of better insulating materials               D) Skewed slots

Answer Key: D

Question No. 10

Which of the following does NOT affect resistance?

 A) Mass              B) Resistivity

C) Cross-sectional area            D) Length

Answer Key: A

Question No. 11

The Power transformer is used to transfer _______ energy in any part of the electrical or electronic circuit between the generator and the distribution primary circuits.

 A) Mechanical             B) Electrical

C) Heat                 D) Chemical

Answer Key: B

Question No. 12

The resolution of an indicating instrument is

A) The smallest change in the output reading due to drifting of the pointer

B) The smallest change in the input signal which can be detected by the instrument

C) The difference between various readings for the same applied stimulus

D) To faithfully indicate the value of the measured signal

Answer Key: B

Question No. 13

______ Theorem states “A branch of a network carrying a current of I amperes can be replaced by a voltage source of value IZ volts where Z is its branch impedance, without affecting the other parts of the network”.

 A) Reciprocity              B) Thevenin

 C) Maximum power transfer         D) Substitution

Answer Key: D

Question No. 14

Two electric lamps of 30 W each are connected in parallel. What is the total power consumed?

A) 15 W                         B) 45 W

 C) 60 W                         D) 75 W

Answer Key: C

Question No. 15

Which of the following single phase motor has the low starting and running torque?

A) Shaded pole             B) Reluctance

C) Hysteresis                 D) Universal

Answer Key: A

Question No. 16

____ Law states that the voltage induced in the coil is proportional to the rate of change of lines of force that pass through the coil.

A) Biot-Savart’s            B) Ohm’s

C) Faraday’s                  D) Lenz’s

Answer Key: C

Question No. 17

______ Theorem is used to combine a number of voltage sources connected in parallel into a single equivalent voltage source

 A) Norton’s                  B) Tellegen’s

 C) Millman’s                 D) Thevenin’s

Answer Key: C

Question No. 18

EPROM stands for

A) Erasable Programmable Read Only Memory

B) Editable Programmable Read Only Memory

C) Editable Programmable Random Only Memory

D) Erasable Programmable Random Only Memory

Answer Key: A

Question No. 19

The residual flux density is also known as

A) Residual induction            B) Residual magnetic induction

C) Residual magnetism         D) All of the options

Answer Key: D

Question No. 20

RMS in terms of electricity stands for

A) Root Mean Sum                B) Root Mean Square

C) Root Maximum Sum        D) Root Minimum Sum

Answer Key: B

NPCIL 2019 Exam paper

SA/ST CAT-I (Electrical)

                                                                      

                                                                          (Electrical knowledge bank)

Question No. 21

Transmission efficiency is the ratio of

A) Power input/Power output       B) Power output/Power input

C) Power input/Voltage drop        D) Voltage drop/Power output

 Answer Key: B

Question No. 22

What is the purpose of earthing?

A) Safety for human life/building/equipment

B) Over voltage protection

C) Voltage stabilisation

 D) All of the options

Answer Key: D

Question No. 23

Which of the following is NOT a transmission medium?

 A) Coaxial cables                   B) Modems

C) Microwave systems          D) Telephone lines

 Answer Key: B

Question No. 24

The SI unit of admittance is

A) Ohm                B) Siemens

 C) Farad              D) Henry

Answer Key: B

Question No. 25

Which of the following is/are a doubly excited magnetic system? A) Reluctance motor        B) Electromagnetic relay

 C) Toroid coil                D) Synchronous motor

 Answer Key: D

Question No. 26

A Wattmeter is an instrument which consists of

A) Voltage coil              B) Current coil

 C) Potential coil           D) Current and Potential coil

Answer Key: D

Question No. 27

Which of the following sources is associated with the radiant efficiency of luminosity?

 A) Current          B) Temperature

C) Pressure          D) Voltage

Answer Key: B

Question No. 28

When there is a change in the strength of the current in a conductor, the change in flux produced by that current establishes counter-EMF in the conductor and this is known as

A) Self induction           B) Mutual induction

C) Magnetic flux           D) Magnetic flux density

 Answer Key: A

Question No. 29

Find the farad equivalent of one micro-farad.

A) 10 farad                              B) 10 farad

C) 10 farad                    D) 10 farad

Answer Key: A

Question No. 30

The system voltage that is defined as the RMS voltage between the conductors is also called

A) RMS phase voltage           B) Peak phase voltage

C) Line-to-line voltage           D) Phase-to-phase voltage

Answer Key: C

Question No. 31

Copper and Bismuth are examples of

A) Paramagnetic materials            B) Diamagnetic materials

C) Ferromagnetic materials           D) none of the options

Answer Key: B

Question No. 32

The primary purpose of a megger is to measure resistances whose values are in the range of

A) μΩ                    B) mΩ

 C) kΩ                   D) MΩ

Answer Key: D

Question No. 33

Which of the following is a static device through which electrical power from one circuit is transferred to other circuit at same frequency?

 A) Transformer            B) Motor

C) Generator                 D) Alternator

Answer Key: A

Question No. 34

Which of the following is the unit of illumination?

A) Radians           B) Lux

C) Lumens                     D) Candela

Answer Key: B

Question No. 35

The maximum AC voltage which can be applied safely across a diode in its non-conducting state is called

A) Peak forward voltage       B) Peak inverse voltage

C) Bias voltage                        D) Supply voltage

 Answer Key: B

Question No. 36

Energy stored in an inductor is given by _____.

 A) (LI)² /2                      B) L² I/2

 C) 1/LI                           D) (1/2) LI ²

Answer Key: D

Question No. 37

Which of the following causes hunting in a synchronous motor? A) When supply voltage fluctuates   B) When changes in load

 C) When power factor is unity     D) Motor is under loaded

Answer Key: B

Question No. 38

The Pitch factor is the ratio of the voltage induced in a

A) Short pitch coil to a full pitch coil

B) Full pitch coil to a short pitch coil

C) Full pitch winding to distributed winding

D) Concentrated winding to distributed winding

 Answer Key: A

Question No. 39

Which of these determines the voltage across the parallel branches of a circuit with more than one voltage source and helps reduce the complexity of that electrical circuit?

A) Reciprocity theorem                  B) Norton’s theorem

C) Compensation theorem            D) Millman’s theorem

Answer Key: D

Question No. 40

Thevenin equivalent circuit consists of

A) Voltage source in series with an equivalent resistor

B) Voltage source in parallel with an equivalent resistor

C) Current source in parallel with an equivalent resistor

 D) Current source in series with an equivalent resistor

Answer Key: A

Question No. 41

In a synchronous motor, the excitation to the field winding for which the induced EMF becomes greater than applied voltage is called

A) Under-excitation               B) Critical excitation

C) Over-excitation                  D) Normal excitation

Answer Key: C

Question No. 42

For measuring high resistance, we should use which of the following?

A) Kelvin’s double bridge                B) Wheatstone bridge

C) Megger                                         D) Galvanometer

Answer Key: C

Question No. 43

The cost of electrical energy generated is reduced when

A) The load factor and diversity factor are high

B) The load factor is high but diversity factor is low

C) The load factor is low but diversity factor is high

D) The load factor and diversity factor are low

Answer Key: A

Question No. 44

Which of the following chemicals is used in the breather for transformer?

 A) Asbestos fiber         B) Silica sand

 C) Sodium chloride     D) Silica gel

Answer Key: D

Question No. 45

______ Type rotor is used for slow speed alternators which have large diameters and small axial lengths.

A) Non-salient pole        B) Salient pole

C) Cylindrical                 D) Smooth cylindrical

Answer Key: B

Question No. 46

Excessive luminances and/or excessive luminance ratios in the field of vision are commonly referred to as

A) Uniform lighting                B) Glare

C) Colour                              D) Illumination

Answer Key: B

Question No. 47

According to ___________ the illumination at any point on a surface is proportional to the cosine of the angle between the normal at that point and the direction of luminous flux.

A) Lambert’s Cosine law                 B) Faraday’s law

C) Coulomb’s law                             D) Law of cosines

Answer Key: A

Question No. 48

The value of susceptibility in case of vacuum is taken as

A) Zero                 B) 0.5

C) Unity                D) Infinity

Answer Key: A

Question No. 49

Capacitive reactance of a capacitor ___________ as the frequency across its plates increases.

 A) Decreases                B) Increases

 C) Equal                        D) Zero

Answer Key: A

Question No. 50

Skin effect exists only in

A) AC transmission          B) DC transmission

C) AC/DC                          D)None of the above

Answer Key: A

NPCIL 2019 Exam paper

SA/ST CAT-I (Electrical)

                                                                          (Electrical knowledge bank)

Question No. 51

___________ states that in an electrical system, three individual single phase powers are carried out by three separate power circuits.

 A) Reactive Power              B) Single phase power

 C) Two phase power          D) Three phase power

Answer Key: D

Question No. 52

Kirchhoff’s loop rule is based on the conservation of

A) Flux                  B) Energy

C) Momentum       D) Impulse

 Answer Key: B

Question No. 53

Which of the following are the factors affecting earth resistivity?

A) Soil resistivity          B) Soil condition

 C) Moisture                  D) All of the options

 Answer Key: D

Question No. 54

Which among the following is the correct expression for impedance (Z) and admittance (Y) ?

A) Z = 1/Y             B) Z = Y

C) Z = Y                 D) Z = 1/Y

Answer Key: A

Question No. 55

The forward drop in voltage of a germanium diode is around _______.

A) 0.7 V                B) 0.3 V

 C) 0.1 V               D) 0.9 V

Answer Key: B

Question No. 56

______ is suitable for EHV/UHV heavily loaded transmission lines.

 A) Mho relay                B) Ohm relay

C) Static relay                D) Impedance relay

Answer Key: A

Question No. 57

A thermal relay works on the principle of

A) Mechanical effect             B) Heating effect

C) Chemical effect                  D) Radiation effect

 Answer Key: B

Question No. 58

The power that continually bounces back and forth between the source and the load is known as

A) Real power               B) Reactive power

C) True power               D) Actual power

Answer Key: B

Question No. 59

_______ is also defined as the ratio of voltage drop appearing across the inductor or the capacitor to the supply voltage.

A) Quality factor          B) Form factor

 C) Power factor           D) Peak factor

Answer Key: A

Question No. 60

Which of the following instruments indicates the instantaneous value of an electrical quantity?

A) Absolute                   B) Indicating

C) Recording                 D) Integrating

Answer Key: B

Question No. 61

The time taken by a sinusoidal signal to complete _______ cycle(s) is called the period of the wave.

A) One        B) Two

C) Three     D) Four

Answer Key: A

Question No. 62

What is the noise factor of an ideal amplifier?

A) 1             B) 0.5

C) 5             D) 15

Answer Key: A

Question No. 63

________ is a component in a fluorescent lighting fixture that controls the voltage and current flow to the lamp.

A) Type IC            B) Type non-IC

C) Ballast             D) Troffer

Answer Key: C

Question No. 64

At resonance condition, the power factor of a series RLC circuit is

A) Infinite            B) Zero

C) One                  D) Two

Answer Key: C

Question No. 65

The slip ring induction motor has

A) Low starting torque          B) Medium starting torque

C) High starting torque         D) Zero starting torque

Answer Key: C

Question No. 66

Which of the following type of switch is used as changeover switch?

A) SPST switch              B) SPDT switch

C) DPST switch            D) DPDT switch

Answer Key: D

Question No. 67

The Skin effect depend(s) on the

A) Diameter of the conductor       B) Supply frequency

C) Shape of the conductor             D) All of the options

Answer Key: D

Question No. 68

_______ effect is the property of some materials, which causes them to change their resistance under the presence of magnetic field.

A) Tens oresistive               B) Photo resistive

C) iezoresistive                  D) Magneto resistive

Answer Key: D

Question No. 69

The algebraic sum of all voltages within the loop must be equal to

A) 0 V         B) 10 V

C) 20 V       D) 30 V

Answer Key: A

Question No. 70

What is the value of Boltzmann’s constant?

 A) 1.38 x 10 J/K            B) 1.38 x 10 J/K

 C) 1.5 x 10 J/K             D) 1.5 x 10 J/K

Answer Key: A

Question No. 71

Two AC voltages are said to be ____ if the phase difference between them is zero.

A) In phase                    B) Out of phase

C) Lagging                      D) None of the options

Answer Key: A

Question No. 72

Depreciation is the inverse of _______ factor.

A) Waste light              B) Maintenance

C) Beam                      D) Absorption

Answer Key: B

Question No. 73

If the angle between the current and voltage is in phase in an AC circuit, then the power factor is

A) Zero                 B) Unity

C) Lagging            D) Leading

Answer Key: B

Question No. 74

The curve between current and frequency is termed as

A) Voltage curve          B) Gain curve

C) Power curve             D) Resonance curve

Answer Key: D

Question No. 75

Damper winding in synchronous motors is used to

A) Suppress hunting               B) Improve the power factor

C) Develop reluctance torque        D) Improve the efficiency

Answer Key: A

NPCIL 2019 Exam paper

SA/ST CAT-I (Electri

                                                                          (Electrical knowledge bank)

Question No. 76

One coulomb of charge is equal to the charge of

A) 1.625 x 10 electrons        B) 1.095 x 10 electrons

C) 6.025 x 10 electrons         D) 6.242 x 10 electrons

Answer Key: D

Question No. 77

If a moving iron instrument is to be used as an ammeter, then the coil has

A) Fewer number of turns of thin wire

B) Fewer number of turns of thick wire

C) Larger number of turns of thin wire

D) Larger number of turns of thick wire

 Answer Key: B

Question No. 78

The ohm’s law of magnetic circuit is

A) Reluctance = flux/MMF             B) MMF = reluctance/flux

C) MMF = flux/reluctance              D) MMF = (flux) (reluctance)

Answer Key: D

Question No. 79

Which of the following DC generators has the rising voltage characteristic?

A) Series                       B) Shunt

C) Cumulatively compound           D) Over compound

 Answer Key: A

Question No. 80

The region between the limits within which a quantity is measured, received or transmitted, expressed by stating the lower and upper limits is called the

A) Range              B) Span

C) Accuracy         D) Sensitivity

Answer Key: A

Question No. 81

Four resistances 2 Ω, 4 Ω, 5 Ω, and 20 Ω are connected in parallel. Find the total resistance value.

A) 1 Ω                   B) 2 Ω

C) 4 Ω                   D) 5 Ω

Answer Key: A

Question No. 82

In modern power plants, the condenser commonly used is

A) Surface type             B) Jet type

C) Both surface and jet type          D) Regenerative type

Answer Key: A

Question No. 83

Which of the following is NOT a non-linear element?

 A) Gas diode                B) Heater coil

C) Tunnel diode            D) Transistor

Answer Key: B

Question No. 84

Phosphor bronze alloy is used for springs in indicating instruments because it has

A) Low resistance to fatigue         

B) Good magnetic property

C) Low specific resistance

D) High temperature coefficient of expansion

Answer Key: C

Question No. 85

Which of the following methods is/are used to reduce corona discharge effect?

A) By increasing the spacing between the conductors

B) By increasing the diameter of the conductor

C) Using Corona rings          

D) All of the options

Answer Key: D

Question No. 86

According to the Right hand thumb rule in electromagnetic induction, direction of what is indicated by the thumb?

A)Motion of conductor             B)Magnetic field

C) Magnetic force                    D) Electric current

Answer Key: A

Question No. 87

Brackets are usually made from ______, which is painted after manufacturing to prevent corrosion.

A) Fibre                B) Wood

C) Flat iron           D) Glass

Answer Key: C

Question No. 88

Which of the following are NOT the reason for using alternating current of sinusoidal form?

 A) Mathematically it is simple

B) Its integrals and differentials both are sinusoidal Top

C) A complex wave form can be analysed

D) The wave form is nondesirable for power generation, transmission and utilisation

Answer Key: D

Question No. 89

When the flux passing from top of one tooth links with the top of another tooth then this flux is called as

A) Slot leakage flux                B) Tooth top leakage flux

C) Over hang leakage flux    D) Skew leakage flux

Answer Key: B

Question No. 90

Find the equivalent resistance of the resistors 20 Ω, 100 Ω and 50 Ω connected in parallel.

A) 5 Ω                   B) 12.5 Ω

C) 15 Ω                 D) 20 Ω

Answer Key: B

Question No. 91

Which of the following is the disadvantage of conduit wiring system?

A) Unsafe wiring system                B) Expensive wiring system

C) Unreliable wiring system               D) Long lasting wiring system

Answer Key: B

Question No. 92

If a wire conductor of 0.1 ohm resistance is doubled in length, its resistance becomes

A) 0.1 ohm          B) 0.02 ohms

C) 0.2 ohms        D) 0.05 ohms

Answer Key: C

Question No. 93

A 200 W, 200 V bulb and a 100 W, 200 V bulb are connected in series and a voltage of 400 V is applied across the series connected bulbs. Which bulb is brighter?

A) 100 W bulb will be brighter than the 200 W bulb

B) 200 W bulb will be brighter than the 100 W bulb

C) Both the 100 W and 200 W bulbs will have equal brightness

D) Both the 100 W and 200 W bulbs will be darker than when they are connected across the rated voltage

Answer Key: A

Question No. 94

An SCR can be tested for its condition with

A) An ohmmeter            B) A line tester

 C) A voltmeter             D) An insulation tester

Answer Key: A

Question No. 95

Magnetic shielding of the operating parts in an electrical instrument is achieved by using

A) Glass cover               B) Brass case

C) Cast iron case          D) Anti-magnetic materials

Answer Key: C

Question No. 96

In a series RL circuit, if the voltages across the resistor and inductor are 3 V and 4 V, respectively, then what is the applied voltage?

A) 7 V                   B) 5 V

C) 4 V                    D) 3 V

Answer Key: B

Question No. 97

The form factor of a pure sinusoidal waveform will always be equal to

A) 1 approximately      B) 11.1 approximately

C) 1.11 approximately   D) 111 approximately

Answer Key: C

Question No. 98

Which of the following are the advantages of bundled conductors?

A) Increases power transmission capacity with reduced power loss leading to increased efficiency of transmission

B) Increases ice and wind loading because of a large cross-sectional area

C) Increases clearance requirements at structures

 D) Increases charging kVA

 Answer Key: A

Question No. 99

The value of the leakage co-efficient of electrical machines is usually about

A) 0.5 to 0.9                  B) 4 to 10

 C) Above 10                 D) 1.15 to 1.25

Answer Key: D

Question No. 100

The synchronous speed of a 4-pole, 50 Hz machine is

A) 750 RPM                  B) 1500 RPM

C) 3000 RPM                D) 3500 RPM

Answer Key: B

NPCIL 2019 Exam paper

SA/ST CAT-I (Electrical

                                                                          (Electrical knowledge bank)

Question No. 101

If R, L, C and G are the resistance, inductance, capacitance and conductance of a transmission line, respectively, the condition for distortionless transmission line is

A) R/C = GL                    B) RC = LG

C) R C = G L                    D) RC = GL

Answer Key: B

Question No. 102

What will be the combined inductance, if two inductances L and L are connected in series?

 A) L + L                                    B) L – L

C) (L + L ) / (L – L )                    D) (L – L ) / (L + L )

Answer Key: A

Question No. 103

Bayonet cap lamp holders are used for lamps of wattages between

A) 0 W – 200 W                      B) 300 W – 400 W

C) 200 W – 300 W                  D) 400 W – 500 W

Answer Key: A

Question No. 104

A rectifier circuit is used to convert

A) DC to AC                             B) AC to AC

 C) AC to DC                            D) DC to DC

Answer Key: C

Question No. 105

Six capacitors each of 6 µF are connected in series, the equivalent capacitance of the system will be

A) 1 µF                 B) 6 µF

C) 12 µF               D) 36 µF

Answer Key: A

Question No. 106

In a transistor, leakage current mainly depends on

A) Doping of the base                     B) Size of the emitter

C) Rating of the transistor              D) Temperature

Answer Key: D

Question No. 107

A Shunt reactor has _______ winding(s) while a power transformer has ______ winding(s).

 A) Single, single                     B) Two, three

C) Single, three                       D) Three, three

 Answer Key: C

Question No. 108

The electric field on an equipotential surface is

A) Unity                B) Always perpendicular to the surface

C) Always parallel to the surface            D) Zero

Answer Key: B

Question No. 109

The Reduction Factor of a source of light is

A) Mean spherical candle power / mean horizontal candle power

B) Mean horizontal candle power / mean spherical candle power

C) 1 / mean spherical candle power

D) 1 / mean horizontal candle power

Answer Key: A

Question No. 110

An EMF of 16 V is induced in a coil of inductance of 4H. The rate of change of current must be

A) 64 A/s             B) 32 A/s

 C) 16 A/s             D) 4 A/s

Answer Key: D

Question No. 111

Depending upon the loading of transmission lines, the _______ which is defined as the sum of the reactive power generation (due to capacitance of the line) and absorption (due to inductance of the line) varies.

 A) Reactive power loss                  B) Real power loss

C) True power loss                           D) Actual power loss

Answer Key: A

Question No. 112

The rotating part of DC machine is called

A) Armature                            B) Pole

C) Carbon brush                     D) Starter

Answer Key: A

Question No. 113

If R = 3 Ω is in series with X = 4 Ω, then the impedance of this circuit Z is

A) 1 Ω                   B) 2 Ω

C) 5 Ω                   D) 7 Ω

Answer Key: C

Question No. 114

Dead zone of an instrument is

A) The time required by an instrument to warm up initially

B) The largest change of input quantity for which there is no output of the instrument

C) The time required by an instrument to begin to respond to a change in measured variable

D) The unmeasured quantity which exceeds the maximum range of the instrument

Answer Key: B

Question No. 115

Which of the following lighting schemes are widely preferred for indoor lighting decoration purposes?

A) General diffuse lighting schemes   B) Semi-direct lighting schemes

C) Indirect lighting schemes       D) Semi-indirect lighting schemes

Answer Key: D

Question No. 116

Which type of wiring will determine whether the panel board is to be mounted on the surface of the wall or whether it is to be flush mounted?

A) Cleat wiring                        B) Concealed conduit wiring

 C) Batten wiring                    D) Casing capping wiring

Answer Key: B

Question No. 117

Turbo alternators have rotors of ______.

A) Smaller air gap diameter and long axial length

B) Large air gap diameter and long axial length

C) Large air gap diameter and small axial length

D) Small air gap diameter and small axial length

 Answer Key: A

Question No. 118

Blocked rotor test on the induction motor is analogous to the _______ test on a transformer.

A) Back to back            B) Open circuit

C) Short circuit              D) Dielectric

Answer Key: C

Question No. 119

A DC Motor having both shunt and series field windings is called a __________.

A) Compound motor             B) Shunt wound motor

C) Self excited DC motor     D) Separately excited DC motor

Answer Key: A

Question No. 120

The chemical equivalent or equivalent weight of a substance in a battery can be determined by

A) Faraday’s law of electrolysis     B) Mutual induction

C) Lenz’s law                 D) Faraday’s law of electro-magnetic induction

 Answer Key: A

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