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Natural capacitance exists between conductors at different potentials, including between those conductors and earth (ground). The value of such capacitance is significantly higher with underground cables than with overhead lines, due to the close proximity of the individual conductors in an underground cable.
Capacitance results in line losses in both a.c. overhead and underground systems, due to the corresponding capacitive reactance (opposition to a.c.). In the case of long, high-voltage, underground or under-sea cables, the capacitance losses can be so high that d.c. transmission is used instead of a.c. (d.c. eliminates capacitive line losses).
In addition to the line losses, the electric fields resulting from the capacitance can lead to insulation breakdown -making it essential that 'sharp corners', etc., are avoided in their design and construction. One of the reasons that high-voltage overhead conductors are 'bundled' (i.e. more than one conductor per line) is to reduce the stress on individual line conductors that would otherwise occur due to their relatively small diameters.
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What are the methods to improve the surge impedance loading of transmission lines?
By increasing Vr,Reducing in series inductance,increase capacitance
What is the basic parameters of transmission lines?
the basic parameters of transmission lines are R,L,C and G...........
Is it possible to transmit dc on ac transmission lines?
DC transmission lines are only used in special applications for example very long distances or for connecting two non-synchronous power systems. As an example UK and France are connected by DC power cables because the two power systems are not synchronised.
What is the difference between pi model and tee model?
For medium length lines the shunt capacitance is uniformly distributed along the length of transmission line.. For simplicity in the calculations, Now in T method the tolal line capacitance is lumped or concentrated at the mid point of the line.While in Pie method the capacitance is divided into two halves whith one half lumped near sending end and other half near the receiving end,The capacitor near the sending end does not contribute any line voltage drop but it should be added with line current to get lotal sending end current.
Why 22kv 11kv 33kv 132kv 220 kv are standard transmission voltages in transmission lines why not 20kv 10kv etc?
Its just a matter of standard. In my area, for instance, we use 13.2 KV for distribution lines, and 69 KV / 138 KV for transmission lines.
Why capacitance is neglected in short transmission lines?
Wen the length of overhead transmission line is less than 80 km with an operating voltage up to 20kv it is considered as short transmission lines Due to smaller lengths and low operating voltage the charging current is low so the effect of capacitance of short transmission lines is extremely small and therefore can be neglected as in case of distribution lines and only R L is to be taken into account while analyzing short transmission lines
What are the methods to improve the surge impedance loading of transmission lines?
By increasing Vr,Reducing in series inductance,increase capacitance
Why are transmission lines less than 80km considered short?
The transmission lines which have length less than 80 km are generally referred as short transmission lines. For short length, the shunt capacitance of this type of line is neglected and other parameters like electrical resistance and inductor of these short lines are lumped.
What are the 4 primary constant and secondary constant of transmission lines?
resistance (R) inductance(L) capacitance(C) shunt conductance(G)
What is transposition of a transmission line?
The balancing effect on account of irregular spacing of conductors can be avoided by changing the position of the conductors at regular distances. this is called transposition of conductors. In case of 3- phase transmission lines, the inductance and capacitance of each phase will be different if the three conductors are spaced differently (each phase to the other two phases, and each phase to ground). the apparent resistance of the conductors is also affected on account of transfer of power between the phases which occur due to mutual coupling. so all the three parameters of the transmission lines are affected by irregular spacing of the conductors.
Effect of high capacitance at no load resulted from the long MV cabling?
No load conditions on lines with large amounts of capacitance will cause the voltage to rise. This is similar to if a cap bank was installed at that location. I'm not sure how much capacitance is really involved at MV; I've never seen this to be a problem. Usually at these voltage levels, the step down transformers have on load tap changers, and can adjust for this. This is often a problem on EHV lines (230kV and above). On these lines, large inductors are used to counteract the capacitance of the line.
What is charging current in transmission lines?
Any two conductors separated by an insulating medium constitutes a condenser or capacitor.In case of overhead transmission lines, two conductors form the two plates of the capacitor and the air between the conductors behaves as dielectric medium. Thus an overhead transmission line can be assumed to have capacitance between the conductors throughout the length of the line. The capacitance is uniformly distributed over the length of the line and may be considered as uniform series of condensers connected between the conductors.When an alternating voltage is applied across the transmission line it draws the leading current even when supplying no load. This leading current will be in quadrature with the applied voltage and is termed as charging current. It must be noted that charging current is due to the capacitive effect between the conductors of the line and does not depend on the load. The strength of the charging currents depends on the voltage of transmission, the capacitance of the line and frequency of the ac supply. It is given by the expressionSignificance of Charging currents:Capacitance effect (responsible for charging currents) of the short transmission lines are negligible. However they are significant in medium and long distance transmission lines.In long distance transmission lines, during light loaded conditions receiving end voltage will be higher than sending end voltage. This is because of the charging currents and capacitive effect of the line
Disconnecting transmission lines 96 jeep?
You can disconnect the 1996 Jeep transmission lines with a 9/16 open end wrench. Be prepared for transmission fluid to come out of the transmission lines.
How can you replace the lines that carry transmission fluid to the transmission?
if you are asking about the cooling lines for the transmission that connect to the radiator, its easy. first disconnect the lines from the radiator (2 lines, usually on the bottom opposite the radiator outlet) then disconnect the lines from the transmission. remove the brackets holding them on, then remove.
What has the author G T Lester written?
G. T. Lester has written: 'Reducing the effects of environment upon two-wire transmission lines'
What is the major material used in constructing transmission lines?
The major material used in the construction of transmission lines is aluminum alloy. Steel is also used to reinforce the lines. No insulation is used for overhead transmission lines.
What is the basic parameters of transmission lines?
the basic parameters of transmission lines are R,L,C and G...........
