Calculation Program of Effective Impedances, Magnetic and Electric
Field Distribution of Catenary Lines
The SIGNON IMAfeb program is used to calculate the effective
impedance of the contact lines of singlephase AC railways
and the crosssectional magnetic and electric field distribution
around contact lines and overhead lines.
The magnetic field emissions of a railway track


with given load flows can be assessed with this program.
Knowledge of the contact line impedances is one of several
important prerequisites for carrying out electrical load
flow calculations with the
SIGNON WEBAnet simulation system.

SIGNON IMAfeb user interface^(click to enlarge)
Initial data
 Structure and material properties of electric conductors
(cross section, radius, equivalent radius  grouping,
conductance, permeability)
 Geometrical layout of the overhead and/or


energy
transmission line in cross section (conductor coordinates).
 Operation frequency, earth conductance and leakage
of return current system

Calculation method
The impedance calculation is carried out according to
the principle of the conductorearthloops coupled inductively
with the consideration of the skin effects in the ferromagnetic
conductors.
The electromagnetic field calculation follows according
to the BiotSavart law. The magnetic field strength value
depends on the conductor currents proportionally and the
inverse proportion of the distance between the conductor
and the coordinate to be calculated in the cross section.
The mutual geometric conductor layout and the phase displacement
are very important for the addition of the magnetic field
strengths. The electric field strength is calculated on
the basis of the method


“mirror charges” with the terrestrial surface as mirror
surface. The relative space permittivity of 1 is accepted
for this calculation.
The priority of the operation functionality of each considered
conductors is necessary for the calculation.
 Conductors: contact wires, messenger wires, feeders,
negative feeder, third rails
 Return conductors: rails, return wires, grounded
band wires, tunnel armour
 Neutral conductors: cable sheath etc.

Example magnetic flux density (click to enlarge)
Results
 Currents, longitudinal voltages and effective impedances
of all defined conductors
 Currents, longitudinal voltages and effective impedances
of all defined circuits (conductor parallel connection)
in table form
 Induced voltages in the conductors laid in parallel
 Total impedance of the return current system and
earth current
 Maximum trackearthvoltage (outside of the transition
sections) for a defined leakage of the return current
system
 Calculation of the magnetic field strength


distribution
in all possible areas around the electrical conductors
(absolute value and polarization of the magnetic strength)
 Calculation of the profiles for the magnetic field
strength, flux density, polarization angle and induced
voltage in different horizontal and vertical cuts or
versus predefined coordinate line
 Calculation of the electric field strength distribution
in air above of the terrestrial surface in all possible
areas around the electrical energy transmission lines

rel. Rail impedance UIC 60 (click to enlarge)