Transmission And Distribution Of Electrical Energy Set 3 MCQs

Q1 | For an overhead line, the surge impedance is taken as

20-30 ohms

70—80 ohms

100—200 ohms

500—1000 ohms

Q2 | The presence of ozone due to corona is harmful because it

reduces power factor

corrodes the material

gives odour

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Q3 | A feeder, in a transmission system, feeds power to

distributors

generating stations

service mains

all of the above

Q4 | The power transmitted will be maximum when

corona losses are minimum

reactance is high

sending end voltage is more

receiving end voltage is more

Q5 | A 3-phase 4 wire system is commonly used on

primary transmission

secondary transmission

primary distribution

secondary distribution

Q6 | Which of the following materials is used for overhead transmission lines ?

Steel cored aluminium

Galvanised steel

Cadmium copper

Any of the above

Q7 | Which of the following is not a constituent for making porcelain insulators?

Quartz

Kaolin

Felspar

Silica

Q8 | There is a greater possibility of occurence of corona during

dry weather

winter

summer heat

humid weather

Q9 | Which of the following relays is used on long transmission lines ?

Impedance relay

Mho’s relay

Reactance relay

None of the above

Q10 | The steel used in steel cored conductors is usually

alloy steel

stainless steel

mild steel

high speed steel

Q11 | Which of the following distribution systems is more reliable ?

Radial system

Tree system

Ring main system

All are equally reliable

Q12 | Which of the following characteristics should the line supports for transmission lines possess ?

Low cost

High mechanical strength

Longer life

All of the above

Q13 | Transmission voltage of ll kV is normally used for distances upto

20—25 km

40—50 km

60—70 km

80—100 km

Q14 | Which of the following regulations is considered best?

50%

20%

10%

2%

Q15 | Skin effect is proportional to

(conductor diameter)

Q16 | A conductor, due to sag between two supports, takes the form of

semi-circle

triangle

ellipse

catenary

Q17 | In AC.S.R. conductors, the insulation between aluminium and steel conductors is

insulin

bitumen

varnish

no insulation is required

Q18 | Which of the following bus-bar schemes has the lowest cost ?

Ring bus-bar scheme

Single bus-bar scheme

Breaker and a half scheme

Main and tr

Q19 | Owing to skin effect

current flows through the half cross-section of the conductor

portion of the conductor near the surface carries more current and core of the conductor carries less current

portion of the conductor near the surface carries less current and core of the conductor carries more cur¬rent

any of the above

Q20 | By which of the following methods string efficiency can be improved ?

Using a guard ring

Grading the insulator

Using long cross arm

Any of the above

Q21 | In aluminium conductors, steel core is provided to

compensate for skin effect

neutralise proximity effect

reduce line inductance

increase the tensile strength

Q22 | By which of the following a bus-bar is rated ?

Current only

Current and voltage

Current, voltage and frequency

Current, voltage, frequency and short time current

Q23 | A circuit is disconnected by isolators when

line is energized

there is no current in the line

line is on full load

circuit breaker is not open

Q24 | For which of the following equipment current rating is not necessary ?

Circuit breakers

Isolators

Load break switch

Circuit breakers and load break switches

Q25 | In a substation the following equipment is not installed

exciters

series capacitors

shunt reactors

voltatre tr