Impedance of power cable

[eejacky]

In the electrical specification of power cable, I found that the positive sequence impedance and zero impedance of 500 mm sq 132kV cable is lower than 500 mm sq 11kV cable. Is the impadance depends on conductor size or other parameters? Any expert can give me advise on this?

 

[dpc]

There can be small differences in resistance due to differences in the stranding of the conductors. The differences should be pretty small.

You should also check to see what temperature is used as a reference point for both resistances given. This can make a significant difference in resistance.

 

[jghrist]

Impedance also depends on the cable spacing and shielding. Larger spacing between phases increases the reactance. Lower shield resistance increases the positive-sequence resistance because shield currents and losses are higher. Thinner insulation also increases the positive-sequence resistance because there is more coupling between the phase conductor and the shield and shield currents are higher. If the 132 kV cable has single-point grounded or cross-bonded shields, there will be no shield losses and the positive-sequence resistance will be lower.

 

[Jerry123]

There are four basic factors that determine the resitance of the conductor.

-Material
-Length
-Cross sectional area
-Temperature

Basic formula is R=P(L/A)
R=Resistance
p=Resistivity
L=Length (ft)
A=Cross sectional area (CM)

Resistivity (p) for copper at 20C is 10.37.

As Length increases resistance is increased. As temperature is increased resistance is also increased. Greater cross sectional area (bigger wire), resistance is decreased.

 

[jbartos]

Suggestion: Visit

http://www.selinc.com/techpprs/underground.pdf

etc. for more info.
Notice that the zero sequence impedance depends on the grounding system of the cable.