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<< Click to Display Table of Contents >> Navigation: The graphical user interface > Circuit Objects > Customizing Components > Open Line/Cable Dialog > Line/Cable Model data |
In the Model data page the user can select type of system and model to construct a LINE CONSTANTS or CABLE PARAMETERS/CABLE CONSTANTS data case. Go to Overview of line/cable modeling.
System type:
•Overhead line: LINE CONSTANTS
•Single core cables: CABLE PARAMETERS/CABLE CONSTANTS
•Enclosing pipe: CABLE PARAMETERS/CABLE CONSTANTS
For overhead line the following data must be specified (high accuracy (FCAR=blank) is used in all cases):
Item |
Description |
Transposed |
The overhead line is transposed if button is checked. If "individual circuits" is checked the SPECIAL DOUBLE CIRCUIT TRANSPOSE card is added to Line Constants. Note: As ATP apparently does not support transposition of PI-equivalents, this is done by ATPDraw as post-processing of the lib-file (averaging elements of the RLC punch cards). Without utilization of the design the diagonal elements will be inaccurate if the conductors have different cross sections. With "individual circuits" checked the transposition typically becomes more correct and works also beyond 6 phases if any ungrounded ground wires are numbered at the end. |
Auto bundling |
When checked this enables the automatic bundling feature of LINE CONSTANTS. |
Seg. ground |
If button is unchecked then the ground wires are assumed to be segmented (discontinuous). This means that zero current flow in the ground conductors and they are simply ignored in the series impedance calculation. |
Skin effect |
If the button is checked skin effect is assumed (IX=4) if unchecked the no skin effect REACT option IX=0 is assumed. |
Real trans. matrix |
If checked the transformation matrix is assumed to be real.The eigenvectors of the transformation matrix are rotated closer to the real axis so that their imaginary part is assumed to become negligible.Recommended for transient simulations. Otherwise a full complex transformation matrix will be used. Recommended for steady state calculations. |
Metric/English |
Switching between the Metric and English unit systems. |
For cables the following data must be specified:
Item |
Description |
Snaking |
If checked the cables are assumed to be transposed |
Cables in |
Select if the cables are in the air, on the earths surface or in ground. |
Cable constants |
Check this box to go from Cable Parameters to Cable Constants. Grounding option will be activated, and the additional conductance and capacitance option will be switched off. The Semlyen model is supported instead of Noda. |
Matrix output |
Check this button to enable printout of impedance and admittance matrix data (R, wL and wC). |
Add G |
Check this button to allow conductance between conductors. Not supported for Cable Constants. |
Add C |
Check this button to allow additional capacitance between conductors. Not supported for Cable Constants. |
Num. cables |
Specify the number of cables in the system. |
For cables with enclosing pipe the following pipe data are required:
Item |
Description |
Depth |
Positive distance in meter between pipe center and ground surface |
Rin |
Inner radius of pipe in meter. |
Rout |
Outer radius of pipe in meter. |
Rins |
Outer radius of outer insulation (total radius) in meter. |
Rho |
Resistivity of pipe conductor. |
Mu |
Relative permeability of pipe conductor. |
Eps(in) |
Relative permittivity of inner insulator (between cables and pipe). |
Eps(out) |
Relative permittivity of outer insulator (around pipe). |
Standard data:
These data are standard for all models. These are part of the standard data structure and can be surfaced in Group components.
Data |
Description |
Rho |
The ground resistivity in ohm*m of the homogeneous earth (Carson's theory) |
Freq. init |
Frequency at which the line parameters will be calculated (Bergeron and PI) or the lower frequency point (JMarti, Noda and Semlyen). |
Length |
Length of overhead line in (m/km/miles). |
Model:
Model |
Description |
Bergeron |
Constant parameter KCLee or Clark models |
PI |
Nominal PI-equivalent (short lines) |
JMarti |
Frequency dependent model with constant transformation matrix |
Noda |
Frequency dependent model (not supported in CABLE CONSTANTS) |
Semlyen |
Frequency dependent simple fitted model (supported in CABLE PARAMETERS from version 3.9) |
The JMarti, Noda and Semlyen models are fitted in a frequency range specified with the number of decades (Decades) from Freq. init and the number of sample points per decade (Points/Dec). The JMarti and Semlyen models also requires a frequency where the transformation matrix is calculated (this frequency should be dominant is the later transient study) and a steady state frequency for calculation of the steady state condition. The Noda model needs a frequency Freq. veloc. where the velocity of the natural modes of propagation are calculated. A value higher than the highest frequency of the frequency scan is usually appropriate. The JMarti, Noda and Semlyen models need in some cases modification of the default fitting data. Please read the Rulebook for further details.