main specific design feature of Automatically Compensated Spatial
Catenary (ACSC) is a new arrangement of the location of the contact wire
and the messenger wire. There are several modifications. The basic
design of an ACSC is shown below.
= plan view
= location of the wires fixed to the supporting pole
= location of the wires under the tunnel vault
= messenger wires
= contact wires
= hinged strips
= fixing strips
catenary consists of two messenger wires and of two contact wires. The
messenger wires are located along both sides of the track axis and they
are rigidly fixed through insulators to supporting points.
contact wires which form a rhombic figure in a horizontal plane are
located symmetrically in relation to the track axis. This is ensured
through linking them with a hinged strip-out at the anchor span whereas
in the middle of the span between two neighboring strips each contact
wire is linked to the corresponding messenger wire through fixing
components. The fixing components have a dual function: they serve as
supporting points for the contact wire and at the same time they are
used to fix the contact wires in relation to the axis of the track.
length of a section of the ACSC is depending on the operational
conditions. On mainlines the length of a section corresponds to the
standard length of presently existing sections whereas on bridges and
in tunnels they are reduced to correspond to the clearance of those
and experimental investigations resulted into developing a specific
feature of the ACSC catenary and that is the self-compensating feature.
the messenger wire and the contact wire being fixed rigidly onto the
anchors the catenary seems to be non-compensated in terms of its form
and implementation but in terms of its operational features it is indeed
compensated. At a loaded status the contact wires generate load which is
transferred to the messenger wires causing thereby a certain
deformation of the latter. This load consists of two forces - a vertical
force stemming from the gravitation force of the contact wire and a
horizontal force stemming from the force generated by the zigzag of the
the temperature goes up the sagging of the messenger wires increases in
the vertical plane while the wire goes down. The contact wires are
expanding under the temperature impact as well as their tensioning
declines. Due to this the angle of sagging of the contact wires changes
at the fixing points and the horizontal forces affecting the messenger
wires change correspondingly. Consequently the load upon the messenger
wire increases as a function of reactional forces caused by the changes
of the angle of fracture of the contact wires.
processes take place in the messenger wires but the forces resulting
thereof remain balanced. The precise corresponding of the changing
forces to the temperature-effected expansion of the components of the
system depends on the type of material used and on the specific design
features of the catenary which are determined through calculations.
horizontal displacement of the wires of spatial type catenaries has been
observed with regard to the longitudinal plane of the track even with a
semi-compensated alternative of this type of catenary. Temperature
effected displacements normally take place in the transversal
direction in relation to the axis of the track.
ability of spatial type catenaries of self-compensation makes it
possible to remove all restrictions as regards the length of the anchor
section which, in this case, primarily is determined by the power supply
and sectionalizing arrangement.
expanding of the anchor sections on mainlines makes it also possible to
do away with such a complex problem like their interfacing. Also there
is no need any more for a frequent adjusting and the reliability of
the catenary as a whole has been improved since most of the damages of
current collectors take place at the points of power supply section interfacing.
the length of the anchor sections in a combination with the
self-compensating feature of the spatial catenary when installing it in
tunnels makes it possible to reduce construction work considerably. This
is attained because cells for the housing of compensators can be
dispensed with since any distance of the tunnel can be spanned with a
single anchor section.
spatial rhombic type of catenary is void of supporting wires as well as
other fixing components which are part of the conventional type of
catenary of mainlines. Due to this maintenance operations become much
simpler. There is no need for any periodic adjustment whatsoever. The
position of the contact wire is adjusted in the longitudinal and
transverse planes during its installation only.
maintenance of such a catenary system can be arranged applying the so
called "module" exchange method. In order to apply this method
only suspension components are required, that is sets of insulators and
components used to fix the contact wire to the messenger wire. The
replacing of any of these components does not require much time. One
more essential feature should be pointed out: the suspension system
consists of standard parts and components only. There is not a single
component which had not undergone intensive testing under operational
environment. Yet the list of components of this catenary is smaller than
that of a conventional catenary. All this contributes to an improved
reliability of the spatial rhombic type of catenary.
case of damages the zone affected is limited this is another most important
operational feature. For instance, in case of disruption of one of the
contact wires of the spatial rhombic type of catenary the tension is
redistributed through articulated strips between the second contact wire
and the messenger wires. The zone affected by the damage is limited to
one link only. The length of the zone remains the same even if both
contact wires are disrupted and this is due to the rigid fixing of the
messenger wires at the suspension points. Thus, the length of the zone
affected by a damage of the contact wires of the spatial-rhombic
catenary is 15 to 20 times shorter (depending on the length of a link)
compared to the vertically suspended type of catenary.
carrying out repair operations involving the joining of the contact
wires no adjustment of the suspension system is required at all. The
contact wires are themselves taking their original position both in the
longitudinal and transversal planes.
there are neither dropping wires nor components to fix them with the new
catenary which would require constant monitoring and maintenance, the
scope of maintenance work is substantially reduced. Moreover, the
complex work involved in the installation and adjustment of the
spatial rhombic type of catenary does not exceed that required with the
conventional type of catenary.
of the most important features of any catenary designs is the change in
the tension of its wires caused by atmospheric impacts that is by the
impact of the temperature and by the load caused by changing the length
of the wires, their positioning and tensioning.
making mechanical calculations of the catenary, based on the knowledge
of the clearance and the tensioning corresponding to certain temperature
and load, parameters are identified which correspond to other
environmental conditions as well. The dependence of the parameters of
the wire upon the changes in the loads is determined, as it is known, by
an equation of the condition.
making calculations of the spatial catenary this tasks turns out to be
far more complex compared to conventional catenaries. The reason for
this lies in the necessity to take into consideration the changes in the
wires in three dimensions which is needed for positioning of wires.
Apart from distributed vertical loads the catenary is exposed to
concentrated vertical and horizontal loads. They can not be replaced by
distributed loads as it is done when making calculations for vertically
suspended catenaries where simplified methods are applied.