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1. The HVDC converter

Does not consume reactive power

Consumes as much reactive power as real power

Consumes 50% of the real power+

2. A back to back HVDC link can be advantageous compared to

AC primarily because

It is cheaper

Of stability considerations

Of controlled power glow+

3. A 12pulse bridge is pre!erred in HVDC because

It eliminates certain harmonics+

It results in better power factor

Series connection of converters on DC side is better

". #ault on a t$o terminal DC link is removed by

!rea"ers on DC side

!rea"ers on #C side

Current control of converters+

% The capacitance and inductance per unit length o! a 3phaseline& operating at 11' kV are .'1 micro!arad and 2.% mH. The

surge impedance o! the line is

50 ohms

500 ohms+

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$50 ohms

(. The )rst HVDC link in *ndia is bet$een

ihand&Delhi+

!allia & !hiwadi

'alcher & (olar

!iswanath & #gra

+. A long transmission line is energi,ed at then sending end

and is kept open circuited at the receiving end. Themagnitudes o! the sending end voltage Vs and o! the receiving

end voltage Vr satis!y the !ollo$ing relationship

)s *)r

)s is greater than )r

)s is less than )r+

- hunt compensation !or long /HV lines is primarily resortedto

Improve voltage prole+

Improve stability

educe fault currents

0 undled conductors are used in /HV lines primarily !or

educing cost of the line

educing corona loss and radio interference+

Increasing stability limit

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1'. /conomic studies have sho$n that D.C. transmission is

cheaper than a. c transmission !or lengths

below ,00 "m

beyond -00 "m+

beyond .$00 "m

11. Transmission voltages in the range 23' kV+(% kV are

kno$n as

/igh voltage

1tra /igh )oltage+

2ltra /igh )oltage

12. hich one o! the !ollo$ing statements is !alse

As the transmission voltage increases&

Corona loss decreases

Conductor copper loss decreases

Cost of insulators3 transformers3 switches 4 circuit brea"ers

increases+

13. The !actors to be considered !or planning HVDC

transmission

Cost

'echnical performance

eliability

#ll of the above+

1". The surge impedance o! a doublecircuit po$er

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transmission line is

0 ohms

$00 ohms+

00 ohms

600 ohms

1%. The surge impedance o! a telephone line is

50 ohms

75 ohms+

$00 ohms

00 ohms

1(. undle conductors are pre!erred in /HV transmission lines

because

It is easy to fabricate thin conductors and combine them to ma"e a

bundle

Inductance of the line is reduced3 and the corona loss3 and radio 4 ')

interference is minimi8ed+

'ower height is reduced and hence transmission cost is low

1+. *nductive inter!erence bet$een po$er 4 communication

lines can be minimi,ed by

Increasing the spacing of power line conductors

'ransposing power line conductors

'ransposing communication line conductors

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ither b or c+

1-. #ind the odd man out in vie$ o! HVDC transmission

9ood voltage regulation

:ow e;ciency+

:esser corona loss

*r?@s

>*s?@r

>*@rs+

>*@r?s

2'. A 12 pulse converter is obtained by series connection o!

t$o bridges $ith

-0 deg phase displacement between two source voltages

,0 deg phase displacement between two source voltages+

.$0 deg phase displacement between two source voltages

A0 deg phase displacement between two source voltages

21. hich o! the !ollo$ing is $rong in the assumption o!analysis o! converter circuit.

'he DC current is constant

)alves are made as ideal switches

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'he DC voltage is Buctuated one+

'he #C voltages are sinusoidal and constant

22. The e6tinction angle is other$ise called as

Delay angle

argin angle+

Commutation angle

iring angle

23. The harmonics contained in the current $ave!orm is givenby

Enp+.F

Enp&.F

EnpG.F+

2". hen the overlap angle is less than (' deg& it is called

'hree and four valve conduction mode

'wo and three valve conduction mode+

'hree valve conduction mode

2%. hich o! the !ollo$ing is not the !eatures o! converter

control

Current order setting can be @uic"ly and reliably changed depending

on the re@uirement

>ower reversal can be done easily and @uic"ly

'he Stability margin is moderate+

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ault current levels are limited to rated values

2(. eries and parallel operation o! thyristor in HVDC

T7A89**:8 results in

or higher voltage and power rating

or higher voltage and current rating+

or higher current and power rating

2+. *n HVDC transmission system& recti)er )ring angle a is kept

near

0H

.5H

,00+

A00

2-. Consider the !ollo$ing statements;

A !ree $heeling diode across the load circuit o! a t$opulse

converter

i< *mproves the operating po$er !actor.

ii< 9akes the distortion !actor =*1 >*

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20. 9ain possibilities o! communication link o! the HVDC

transmission

Short wave radio lin"

>ilot wires

'he use of carrier fre@uency on the power conductors

#ll the above+

3'. The control o! po$er in a DC link can be achieved through

Control of voltage of current

Control of current

Control of current of voltage+

Control of voltage

31. The e6citation angle controller can be controlled by

>redictive type

eedbac" type

!oth i 4 ii+

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!oth I4II+

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)oltage rating

!oth voltage and current rating

ower factor obtained in ac side+

Decrease >ower factor obtained in dc side

increase >ower factor obtained in dc side

decrease power factor obtained in ac side

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"'. 9ention the per!ormance criteria !or selection o! harmonic

)lter

/armonic distortion

'elephone inBuence factor

ositive conductor+

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"". hat are the e?ects o! trouble caused by harmonics

/armonics

)oltage collapse

Over heating+

Decrease magnetic loss

"%. The inde6 THD can be calculated !or

Current

)oltage

Current and voltage

Current or voltage+

"(. hat are the means to reduce harmonics

2sing lter and increasing the pulse number+

Decreasing pulse number

2sing lter only

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output is

>arity simulator+

>hysical simulator

#nalog computer

Digital computer

%'. 5ractical dielectrics used in HVDC cables.

>aper

Impregnated paper and polythene+

Castor oil

>lastic