For a 400 kV
line the spacing between phase conductors is around :
An overhead
line has a span of 250 metres, the line conductor weighs 612 kg per 1000
metres. The maximum sag in the line, if the maximum allowable tension in the
line is 1430 kg, will be
The transmission line feeding power on either side of the main
transmission line is called
When voltage
exceeds 650 volts and does not exceed 33 kV subject to variation permissible in
I.E. Rules, it falls under the category of
According to
I.E. Rule all metal supports of O.H. lines be permanently and efficiently
earthed. This can be done by
One which of
the following factors the sag of transmission line conductor does not depend
on?
In case of
transmission line conductors with the increase the atmospheric temperature
Multi strand
conductors are preferred over solid conductors because they are :
The ground conductor in case of high transmission lines is used to
The sag
produced in the conductor of a transmission line depend on :
When a high
voltage overhead line passes over or adjacent to any building the vertical
clearance between the highest part of the building immediately under such
lines, recommended in IE rules is of not less than :
The sag of a
transmission line conductor in summer is________.
Copper conductors are generally used for transmission lines because
it________.
Copper has
less resistance than aluminium and has greater tensile strength than aluminium.
To work, copper proves an excellent material as compared to aluminium. In spite
of this, now a days aluminium is extensively used in transmission and
distribution of power supply because :
An overhead
transmission line has a span of 220 m between two supports at the same level.
The conductor weights 804 kg/km. Assuming a safety factor of 2, what is the
maximum sag if the ultimate tensile strength of the conductor is 6000 kg?
In a 3-phase, 4 wire system, generally the area of cross-section of
neutral wire
Between two
supports, due to sag the conductor takes the shape of
The
difference of level between the points of support and the lower point of the
conductor of a transmission line is________.
The number of
conductors in a double circuit transmission line is
If the
frequency of a transmission system is changed from 50Hz to 100Hz, the string
efficiency_________.
The conductor tied between two supports tot the shape of a 'catenary'
due to_________?
If span
length is doubled with no other factors, the sag of the line will become?
The sag of
the conductors of a transmission lines
is 2.5 m when the span is 250 m. Now if the height of the supporting towers is increased
by 2.5%, the sag will
In high
voltage transmission lines, the topmost conductor is :
The presence
of earth in case of overhead lines
Which of the
following statement is incorrect?
Bundled
conductors in EHV transmission system provide :
For a three
layer stranded wire, the number of strands in first, second and third layer
respectively are :
The type of
steel tower used to transmit power at 800 kV is a :
In river
crossings, modern high voltage lines have a span length of :
The sag of a
transmission line depends upon :
Sag is provided in the transmission lines so that
Bundle
conductors are used to :
Which one of
the following is reduced by using stock bridge dampers on power overhead
transmission lines?
In a 7/30
ACSR conductor why is grease put between steel and aluminium conductors?
For a 66 kV
line having span of 200 meters between towers the approximate sag will be 2 m.
If the span is double the sag will be :
The sag of a transmission line is least affected by
Aluminium is mostly preferred as a bus material because of it's :
None uniform
distribution of variable currents is solid conductors resulting in an increase
in the current density near the surface :
Under no load
conditions the current in a transmission line is due to
For a transmission line, the no load receiving end voltage is more than
the sending end voltage. This is called.
The
characteristic impedance of a transmission line depends upon
Stringing
charts are useful for
If sag on a
transmission is increased, the tension will :
Consider the
following statements regarding aluminium conductor steel reinforced conductors
in transmission lines. State whether these statements are true or false.
1. It is
cheaper than copper conductor of equal resistance.
2. Corona
losses are reduced in it because of the larger diameter of the conductor.
3. It has
lesser mechanical strength, so it needs more support for a particular length of
transmission line.
Which of the
following CANNOT be used for improving string efficiency of insulator?
The effect of wind pressure is more predominant on :
If the length
of the cross-arm of tower is increased what is the net effect on the string
efficiency?
A string of
suspension insulators has three discs. If the disc nearest to the conductor
flashes over, then
If the string
efficiency is 100%, it means that