This section describes the line data used in network calculations.

 

The key data in attribute form for individual line section:

   • Line type: chosen from the codelist for line types and rated data. See the corresponding description below.

   • Laying type: chosen from the codelist for laying types which determines maximum permissible load current. See the corresponding description below.

   • Correction factor: adjusts rated current for a given line section. See the description of maximum permissible load current below.

   • Total length: used for calculation of the length-dependent electrical parameters (e.g. resistance, inductance).

 

Line type and rated data

 

Line types with the corresponding rated data are defined in the following codelists:

ELOHCBLTYPE_CL for OH cable.

ELUGCBLTYPE_CL for earth/sea cable.

ELINSLINETYPE_CL for insulated free line.

ELUNINSLINETYPE_CL for uninsulated free line.

 

These codelists have the same structure and format. The fields used in network calculations are described below.

Description of data necessary for the calculation program.

Phase max temperature
See appendix Earth faults using increased resistance due to warm conductors

Phase start temperature
See appendix Earth faults using increased resistance due to warm conductors

Phase temp coefficient
See appendix Earth faults using increased resistance due to warm conductors

Neutral max temperature
See appendix Earth faults using increased resistance due to warm conductors

Neutral start temperature
See appendix Earth faults using increased resistance due to warm conductors

Neutral temp coefficient
See appendix Earth faults using increased resistance due to warm conductors

Feeder phase res.increase
See appendix Earth faults using increased resistance due to warm conductors

Feeder neutral res.increase
See appendix Earth faults using increased resistance due to warm conductors

Service phase res.increase
See appendix Earth faults using increased resistance due to warm conductors

Service neutral res.increase
See appendix Earth faults using increased resistance due to warm conductors

Cable diameter mm

Used for parallel cable cases. Calculates the mutual impedance where appropriate.

Operating capacitance mikroFarad per km
Participates in the load flow calculation, gives a capacitive contribution to the load current, necessary for the calculation of the capacitive no load currents.
The term "Operating capacitance" includes both the neutral sequence capacitance and the capacitance between the conductors.
If each phase is individually earth screened no capacitance between the phases will occur and hence the operating capacitance should only contain the neutral sequence capacitance. Else the relation between the neutral sequence capacitance and the operating capacitance could be approximated to 1:3 - 1:2.

Phase inductance, mH/km
The phase conductor inductance. If only the phase reactance is available in ohm/km it can be recalculated to mH/km according to:
Phase inductance mH/km = 10 / π * phase reactance (ohm/km).

Phase resistance ohm/km
The phase conductors resistance

Neutral inductance mH/km
The neutral conductor inductance. For a cable with a concentric neutral conductor this value should be = 0
If only the neutral reactance is available in ohm/km it can be recalculated to mH/km according to:
Neutral inductance mH/km = 10 / π * neutral reactance (ohm/km).

Neutral resistance ohm/km
The neutral conductors resistance

Earth capacitance mikroFarad per km
Neutral sequence capacitance for phase conductors.
Is used for calculating earth fault currents/impedances.
If only the earth fault current is known the earth capacitance can be recalculated as:
ECap = Earth fault current / (3 * Phase voltage * 100 * π)

Phase short time current. (A)
Max allowed short time current for a phase conductor (1 sec). Is used to verify that the conductor can withstand a short circuit current.

Neutral short time current. (A)
Max allowed short time current for a neutral conductor (1 sec). Is used to verify that the conductor can withstand a short circuit current.

Rated current

Rated current (Ampere), default value. See the description of laying type and maximum permissible load current below.

Rated current alt. A

Rated current (Ampere), alternative value A. See the description of laying type and maximum permissible load current below.

Rated current alt. B

Rated current (Ampere), alternative value B. See the description of laying type and maximum permissible load current below.

PE cross section, PE inductance, PE resistance
Preparation for calculation with Protective Earthing conductors, ie 5 conductor systems. Currently not used by the system.

Mutual inductance p-p, mH/km.
Mutual inductance phase to phase, used only by the Unbalanced Load Flow calculation program.

Mutual inductance p-n, mH/km
Mutual inductance phase to neutral, used only by the Unbalanced Load Flow calculation program.

Laying type and maximum permissible load current

Laying types for power lines are defined in the codelist ELCBLLAYING_CL. Each laying type is described with the following fields:

   • Laying type: short name (shown in line’s attribute form).

   • Description: optional detailed description.

   • Type of rated current: it determines which rated current (default, alt. A or alt. B) to be used from the codelists with line's rated data.

   • Correction factor: it adjusts rated currents for a given laying type.

At new installation the codelist ELCBLLAYING_CL contains two alternative laying types Type A and Type B. They can be modified and new laying types can be added.

Line’s attribute form and the codelist ELCBLLAYING_CL provide several possibilities to adjust the maximum permissible load current for a line section. Analyzer uses the following steps for calculating maximum permissible load current:

   1. Get the correction factor from the field in the line's attribute form. If it is missing, get the value from the codelist ELCBLLAYING_CL based on the laying type. If it is missing too, use the value 1.

   2. Get the rated current type from the codelist ELCBLLAYING_CL based on the laying type. If undefined, use the default type.

   3. Get the rated current value based on the line type and the rated current type.

   4. Multiply the rated current value by the correction factor.