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A power system will have greater flexibility of operation if they have __________
d) Only thermal power plants operating in combination
d) Only thermal power plants operating in combination
See lessAn overhead transmission line has a span of 220 metres the conductor waiting 0.604 kg/m. What will be the maximum sag if the working tension is 2879 kg.
d Explanation: (Maximum sag ) S = ωL2 /8T Where , ω – weight of conductor per meter L – span T – Working tension Therefore, S = (0.604×2202)/(8×2879) = 1.269 m ~ 1.27 m.
d
See lessExplanation:
(Maximum sag ) S = ωL2
/8T
Where ,
ω – weight of conductor per meter
L – span
T – Working tension
Therefore, S = (0.604×2202)/(8×2879)
= 1.269 m ~ 1.27 m.
‘Dancing’ of overhead conductors occurs during which of the following types of vibrations?
b Explanation: During galloping vibrations in overhead transmission lines conductors vibrates with high amplitude ( about 6 m ) and low friquency (about 1 or 2 Hz). Swinging of conductors with high amplitudes in horizontal and vertical directions are called as they are ‘dancing’
b
See lessExplanation: During galloping vibrations in overhead transmission lines conductors
vibrates with high amplitude ( about 6 m ) and low friquency (about 1 or 2 Hz). Swinging
of conductors with high amplitudes in horizontal and vertical directions are called as they
are ‘dancing’
Which of the following vibrations causes different conductors to touch due to high swing?
b Explanation: Galloping vibrations in overhead transmission lines are high amplitude ( about 6 m ) vibrations. During such vibrations conductors ‘dance’ in horizontal and vertical directions with high amplitude which makes the conductors to touch each other.
b
See lessExplanation: Galloping vibrations in overhead transmission lines are high amplitude (
about 6 m ) vibrations. During such vibrations conductors ‘dance’ in horizontal and
vertical directions with high amplitude which makes the conductors to touch each other.
What will be the resultant weight on per meter of length of conductor if weight of conductor is 150 kg/m, weight of ice in per meter of length is 60 kg/m and wind force is 200 Kg/m.?
c Explanation: Resultant stress = √[{(wc + wi )2 + ww 2 }] = √[{(150 + 60 )2 + 2002 }] = 290 kg.
c
See lessExplanation:
Resultant stress = √[{(wc + wi )2 + ww
2
}] = √[{(150 + 60 )2 + 2002
}] = 290 kg.
When the sag exceeds 10% of the span length, the shape made by the conductor is similar to which of the following shape?
c Explanation: A flexible wire of uniform cross section when string between two suppose at the same level will form a category however if the sag is very small as well as less than 10% of the span length then its shape approximates a parabola.
c
See lessExplanation: A flexible wire of uniform cross section when string between two suppose at
the same level will form a category however if the sag is very small as well as less than
10% of the span length then its shape approximates a parabola.
An overhead transmission line has a span of 220 metres the conductor waiting 0.604 kg/m. What will be the maximum sag if the working tension is 2879 kg
d Explanation: (Maximum sag ) S = ωL2 /8T Where , ω – weight of conductor per meter L – span T – Working tension Therefore, S = (0.604×2202)/(8×2879) = 1.269 m ~ 1.27 m
d
See lessExplanation:
(Maximum sag ) S = ωL2
/8T
Where ,
ω – weight of conductor per meter
L – span
T – Working tension
Therefore, S = (0.604×2202)/(8×2879)
= 1.269 m ~ 1.27 m
In extra High Voltage lines, which conductor material is used for ground wire provided above the line conductors for protection against lightning?
c Explanation: Due to very poor conductivity, about 30% of copper and higher eddy current and hysteresis losses. Application of galvanized steel wire is limited to telecommunication lines stay wire Earth wire and guard wires. Stranded galvanized steel wires are used as guy wires and earth wires
c
See lessExplanation: Due to very poor conductivity, about 30% of copper and higher eddy
current and hysteresis losses. Application of galvanized steel wire is limited to
telecommunication lines stay wire Earth wire and guard wires. Stranded galvanized steel
wires are used as guy wires and earth wires
Which of the following conductive material will be preferred when harmful gases such as ammonia are present in atmosphere?
b Explanation: When harmful gases such as Ammonia are present in atmosphere and the spans are extremely long, phosphor bronze is most suitable material for an overhead line conductor for such situation.
b
See lessExplanation: When harmful gases such as Ammonia are present in atmosphere and the
spans are extremely long, phosphor bronze is most suitable material for an overhead
line conductor for such situation.
Which of the following conductors are most suitable for short lines supplying rural areas and operating at voltage of about 11 Kv?
c Explanation: Galvanized steel have great tensile strength and so it can be used for extremely long spans,or for short line section exposed to normally high stresses due to climatic conditions. These conductors are most suitable for lines supplying rural areas and operating at voltages of about 11Read more
c
See lessExplanation: Galvanized steel have great tensile strength and so it can be used for
extremely long spans,or for short line section exposed to normally high stresses due to
climatic conditions. These conductors are most suitable for lines supplying rural areas
and operating at voltages of about 11 Kv where cheapness is the main consideration