8/11/2019 EE2303 Transmission and Distribution - Problems for Practice

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UNIT 1

A transmission line conductor at a river crossing is supported from two towers atheights of 70 m above water level. The horizontal distance between towers is00 m. If the tension in conductor is 1!"00 #g! $nd the clearance at a pointmidwa% between the towers. The size of conductor is 0.& cm'. (ensit% of

conductor material is ).& g*cm and suspension length of the string is ' metres.

The e+ective diameter of a line is 1.&, cm and it weighs &0 #g per 100 metrelength. -hat would be the additional loading due to ice of radial thic#ness 1.'"cm and a horizontal wind pressure of 0 #g*m' of proected area/ Also! $nd thetotal weight per metre run of the line. (ensit% of ice is &'0 #g*m.

A transmission line has a span of 1"0 metres between supports! the supportsbeing at the same level. The conductor has a crosssectional area of ' cm'. Theultimate strength is "!000 #g*cm'. The speci$c gravit% of the material is ).&. Ifthe wind pressure is 1." #g*m length of the conductor! calculate the sag at thecentre of the conductor if factor of safet% is ".

A transmission line conductor at a river crossing is supported from two towers atheights of '0 m and ,0 m above water level. The horizontal distance betweenthe towers is 00 m. If the tension in the conductor is 1)00 #g and the conductorweighs 1.0 #g per metre! $nd the clearance between the conductor and thewater level at a point midwa% between the towers.

A conductor is strung across a river! being supported at the two ends at heightsof '0 m and 1, m respectivel%! from the bed of the river. The distance betweenthe supports is 7" m and the weight of the conductor 1.' #g*m. If theclearance of the conductor from the river bed be & m! $nd the horizontal tensionin the conductor. Assume a parabolic con$guration and that there is no wind or

ice loading.

UNIT II

-hat is the inductance per loop metre of two parallel conductors of a singlephase s%stem if each has a diameter of 1 cm and their a2es are " cm apart whenconductors have a relative permeabilit% of 3a4 unit% and 3b4 100. The relativepermeabilit% of the surrounding medium is unit% in both cases. 5nd e+ects ma%be neglected and the current ma% be assumed uniforml% distributed over crosssection of the wires.

A '0#m singlephase transmission line having 0.)' cm diameter has two line

conductors separated b% 1." metre. The conductor has a resistance of 0.11 ohmper #ilometre. 6ind the loop impedance of this line at "0 z.

A singlephase line has an impedance of "8 ,09 and supplies a load of 1'0 A!!00 : at 0.) p.f. lagging. ;alculate the sendingend voltage and draw a vectordiagram.

An overhead! singlephase transmission line delivers 1100 #- at #: at 0.) p.f.lagging. The total resistance of the line is 10 < and total inductive reactance is1"