Dear  Chintan Patel

X of a line is depend on many factors such as line distance, Bundling type and .... 

in a power distribution system, Length  of  lines are much shorter than power transmission lines. there fore the inductance of power line has a low value. so in a power distribution system R/X ratio is higher than transmission system.

if  you agree with my answer, please approve this.

thanks

the long run of transmission lines connected in grid pattern causes fall in resistance. the bundled conductors are generally used for transmission lines.

the distribution network are generally not connected in grid pattern for every feeder. 

single ACSR conductors are used for distribution systems.

The resistance of a conductor is calculated by formula R = ro * L / A. 

In the distribution network area of the conductor is kept small because it has to carry small current compared to transmission network. Therefore, the resistance of the distribution network is high which results in high R/X ratio. 

dear Chintan Patel you got so many answers about why the R/X ratio  is higher in distribution than transmission , 

because of higher length the effective resistance is more in transmission & for reducing losses like corona & ferranti ,we choose bundle conductor , done  cable grading in such a manner that potential becomes equal so reduces the reactance .

High R/X  ratio has positive effect it ensures power transfer  in good manner ,stability also increases .

lower R/X ratio creates the condition of line outage and also causes extra heat up of transmission line .

In a power distribution system R/X ratio is higher than transmission system due to the shortness in line length and the low voltage level

Basically the reason for high R/X ratio is high value of resistance in Distribution lines.

Since we are basically talking about the ratio of R and X distance does not play a major role.    

The simple reason would be due to the line spacing between the conductors. As you know, the spacing is very less typically 60 cms in 400V or 11kV whereas transmission line has a spacing of around 6m between their conductors. As inductance is directly proportional to the product of roots of spacing, a typical transmission line has a much higher ratio of (X/R).

x/r ratio is the ratio of reatance of the line and

resistance of the line. In distribution lines like 400 volt

three phase line, the resitance is far high than reactance

or we can say the reactance is negligible as compared to R.

Therefore x/r ratio of dist.line is less than 0.01. for

11kv line this may be less than 0.1.

THis ratio increases as we move towards high and Exta high

votage lines.

Hello,

Usually, underground cable (UGC) are used in the power distribution, while the overhead lines are rarely used. Generally, the length of the power distribution circuits are shorter than the length of the transmission, and sub-transmission circuits. In addition, the alloys of the UGC conductors are relatively harder in comparison with overhead line. These are the reasons that cause the increases R/X in UGC in comparison with overhead lines. You may read

Article Modeling and analysis of reactive power in grid‐connected on...

It is interesting to note that this point has created lot of discussions and there is no new information that has to be added.

It is very obvious that R/X ratio of transmission line will be less than power distribution line. The reasons are:

1. Spacing between conductors phases: In distribution line the phases are placed proximity to each other unlike transmission. Due to its less spacing reactance of distribution network is less than transmission network.

2. Effective Diameter: If you observe, you will find that effective diameter of distribution line is higher compared to transmission line due to different conductors are used in transmission & distribution. Due to reduction of effective diameter of conductor by skin effect, ACSR conductors are used. But there is no such problem in distribution line so solid aluminum or stranded conductor are used. That the reason of higher effective diameter of distribution lines.

3. Effective Resistance: Due to skin effcet. corona loss the effective resistance of conductor is reduced due to greater inductance in inner strands than outer strands. Therefore R is less in transmission lines than distribution lines.

3. Bundled Conductors: Bundled conductors are economical for use beyond 220kV. Normally to get rid of from skin effect & corona loss, it is preferably used. But by using it, the ampacity i.e current carrying capacity is much increased compared to single conductors. Therefore the effective resistance is always lower in transmission line while design compared to distribution lines.

Due to all the aforementioned reasons, R/X ration of transmission line is less.

Simple answer is that: (1) for transmission line R/X ratio is small value for improving power transfer capacity by reducing the power loss, because here if R/x ratio is higher means some times says ill condition for transmission line. (2) for overhead distribution system R/X ratio is high (distribution design point of view). (3) for underground transmission line R/X ration is again higher than overhead distribution line.

Type of conductor is also affects on this ratio.

Dear Chintan,

I came late but the question is interesting and this is my answer:

Adding to the colleagues, from the conceptual point of view any transmission line has four parameters per meter. It has an inductance L .of its conductors , a resistance R of its conductors,  a capacitance C between its conductors and a leakage conductance G between its conductors. The value of these parameters depends on the construction of the the transmission line; the cross section of its conductors, the material of its conductors, the distance between its conductors and the insulator between its conductors. The transmission line used to transmit electric power works at much higher voltage than the the distribution wire. There fore the distance between the wires is made much larger than the distribution line which leads to much higher magnetic energy storage and consequently its inductance per unit length will be higher.

Concerning the resistance which depends on the cross section and material type it will be comparable for the same carrying capability because the cross section's sized to limit the ohmic losses.

Accordingly the w L/R= X/R ratio of the transmission line will be higher than that of the distribution line for the same current ratings.

wish you success