Line Charging Susceptance
Line Charging Susceptance
(OP)
I have to come up with a bunch of data for the System Operator. We've managed to pull most of the data together except for the "Line Charging Susceptance" of an underground cable. I'm not an Electrical Engineer so any help on how I can come up with this will be greatly appreciated. I've checked all existing documents on site to no avail.






RE: Line Charging Susceptance
They are(basically)looking for the charging capacitance.
If you know what complex impedance is ( Z = R + jX), then the "Admittance" is the inverse of this. The "Susceptance" is the imaginary portion of the "Admittance". They are looking for the "shunt" admittance of the line, as opposed to the series impedance you've probably already figured out. The admittance is a complex number - the real part is conductance and the imaginary part is susceptance. The shunt conductance of an overhead line is negligible, so that leaves the susceptance, which reduces to the inverse of the capacitive reactance.
For short overhead lines, this value is not of major concern. For long underground lines and very long transmission lines, it is of more interest.
Not sure how you came up with the other data, but a book like Stevenson's Elements of Power System Analysis, or similar text should help you out.
Cheers,
Dave
RE: Line Charging Susceptance
C = E*10^-9/(18*ln(Di/dc)) in farad/m
Where E is the relative permeability (3 for EPR, 2.5 for XLPE)
Di is the external diameter of the insulation excluding the screen
dc is the diamter of the conductor including screen
Susceptance = 2*pi*f*C
RE: Line Charging Susceptance
Thanks
RE: Line Charging Susceptance
RE: Line Charging Susceptance
Thanks
RE: Line Charging Susceptance
RE: Line Charging Susceptance
Your answers are greatly appreciated!