tech. sc., prof. Rector, All-Union Railway Engineer Training Institute (by
reliable and cost saving catenary determines to a large extent the
efficiency of electric power supply for train haulage and for railway
operation at large.
from conventional requirements to be met by catenaries such as high
reliability at all weather conditions and economic efficiency a number of
new features should be covered. The main of them are the following: to
be maintainable with the minimum manual work involved while ensuring trouble-free
train traffic, substantial saving of time required to remove possible
damages, raising the efficiency of the operation of electrified lines;
ensuring reliable operation of high speed traffic on electrified lines,
facilitating the maintenance of tracks and fixed installations in
particular on sections being considerably lifted during renewal operations;
raising the safety standard of catenary maintenance practice under
condition of high traffic density by reducing the volume of work involved
in running maintenance and in removing possible damages due to limiting
the affected zones.
review of known types of compensated catenaries shows they incorporate the
following disadvantages: lack of uniformity of tension within the limits
of anchoring sections, substantial changes in the parameters in case the
catenary is exposed to additional loads caused by the wind and icing;
complexity of the compensating devices which require constant monitoring;
insufficient rigidity of the suspension resulting into sagging of the wire
at high speed traffic which initiates damaging of the pull-off and current
collecting devices (especially when several current collectors are in
operation simultaneously); substantial work required to adjust the
suspension arrangement and to maintain the pre-set parameters during train
traffic; an extremely long zone of damage in case a rupture of the wire of
the catenary occurs.
big variety of catenary designs, deficiencies of some catenary designs,
and their complexity call for a continuous search for optimum alternatives
with- increased reliability, with improved cost/benefit characteristics
and increased labour productivity of the maintenance personnel.
order to meet more fully the requirements of a catenary designed to be
used in severe operational conditions a new type of catenary has been
developed that should meet the following requirements. The catenary must
have a limited vertical clearance, it should be of a simple design using
standard components and parts only with no requirements for adjustment
during operation. Moreover, the catenary must insure a high level of
operational reliability, it should incorporate perfect dynamic
properties and, what is most important, the zone of damage in case of a
rupture of wires of the catenary should be many times smaller than that
with the chain type catenary.
main specific design feature of this type of the catenary is a new
arrangement of the location of the contact wire and the messenger wire.
This type of catenary may be called Automatically Compensated Spatial
Catenary (ACSC). There are several modifications. The basic design of an
ACSC is shown in Fig. 1.
= 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.
1: Spatial rhombic type of catenary
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 structures.
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 contact wires.
The system of messenger wires and contact wires becomes prestressed.
the temperature goes up the sagging of the messenger wires increases in
the vertical plane while the wire goes down. The conlact 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
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 curren!
collectors take place at the points of power supply section interfacing.
the length of the anchor sections in a combination with the
selfcompensating 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
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 more
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 which 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
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.
the spatial rhombic type of catenary the concentrated forces having an
impact on the messenger wires are applied at the points to which the
contact wires are fixed. These points are located within one link at
distances of 15 to 17 meters and they are strictly defined.
equation*1* of the status of the wires for the spatial rhombic type of
catenary is as under:
The formulae might have been imperfectly transmitted and may contain some
errors (Editor's note)
2 and 3 show the installation diagrams for short links used in tunnels as
well as on open sections. Fig. 2 represents" the interdance of the
tensioning of non-loaded wire Tpx on the temperature t, while on Fig. 3
the installation diagram is shown of both a non-loaded wire which is being
installed (curve Tpx) and a loaded messenger wire (curve Tx).
the curves in Fig. 2 and Fig. 3 one can see that as the length of the link
is increased the range of change of the tensioning of the messenger wires
of the spatial rhombic catenary gets smaller and this means, that the
changes of vertical clearances caused by temperature changes are less.
2: Installation diagram of a non-loaded messenger mire of the 2 CM-95 + 2M
-100 catenary with two rhombs of the contact wire in 18,24 and 30 m links
3: Installation diagram of the messenger wire with four rhombs of the
contact wires in 64,5 m links
installation diagrams of the catenary for tunnels (as it is shown in
Fig.2) are indicating the range of changes caused by ambient temperature
changing within a span of 80°C, that is to say that it is the same as for
open air sections. As a matter of fact, practical experience proves that
in tunnels the temperature deviates from the average value within a range
of 5 to 10°C only. Thus, the catenary will ensure reliable operation
under minor changes in the ten-sioning of the messenger wire. This feature
ensures the stabilizing of the clearances in the course of operation.
of the most important requirements of high speed lines is a proper
rigidity of the catenary. And not only the magnitude of instability is
important but the nature of changes occurring all over the length of the
section is taken into account.
rigidity determines the static properties of catenaries and it is a
function of the force, applied to the contact wires, and the caused
protrusion of the wires. The theoretical investigations into the
rigidity of a link of a spatial rhombic type of catenary are rather
complex and an individual approach is required when a specific design is
to be evaluated. The complexity of the problem lies in the fact that the
rigidity feature is primarily determined by the design of the catenary
with regard to the suspension component and to the behaviour of the middle
part of the link, by the metrical parameters etc.
method of making calculations for the rigidity of the spatial rhombic type
of catenary has been improved compared to that used to make calculations
of the conventional catenary. One had to take into account the impact of
forces in three dimensions.
calculated values obtained are of a universal nature. They take into
account the impact neighbouring links have upon the one under
consideration as well as the effect other parameters of the catenary have,
such as the type of wire used, its tensioning etc. The size of the links
of the contact system and the distance between the points of placing
fixing components may be different depending on the various designs of the
catenary. This makes it possible to choose the parameters for each
individual design of the catenary so as to meet best the optimum
conditions of the interacting of the current collector with the spatial
quality of current collection is the better the less the deviation of the
contact pressure from the pre-set optimum value covering the whole of the
link. The best condition for high quality current collection is when the
rigidity is the same at any point of the link. In order to determine the
impact the various parameters of the suspension components have upon the
distribution of the rigidity over the entire link, the notion of
coefficient of rigidity is used which is the relation of maximum "rigidity
to its lowest value. The closer the coefficient value comes to the
figure one the better are the conditions for current collecting. When
the rigidity coefficient is close to the figure one then the catenary is a
uniformly elastic system. In this case the conditions of the interaction
between the pantograph and the catenary is considered to be optimal.
rigidity value and the nature of its distribution over the link can be
controlled through the change in the design of the spatial catenary. The
displacement of the fixing components in relation to one another on the
link results in distorting the regular rhombs formed by the contact wires.
Mention should be made that the points at which the contact wire is
secured to the messenger wire and at which the suspension system is most
rigid, are shifting with regard to corresponding points of the second half
of the link while the overall rigidity wilhin the link does hardly change
at all. The value of the coefficient can be reduced by 20% on links in
case when the distance between components are equal to one third of the
distance between the articulated joints connecting the contact wires
within the link.
70 meter links of mainlines the calculated coefficient lies within 1,40
and 1,19 for any tensioning value of the messenger wire. The testing of
the spatial rhombic catenary has proved that the rigidity of the
suspension within 55 to 70 meters at temperatures ranging from 15 to 20°C
remains practically constant at all points, that is, the coefficient of
non-uniformity of the distribution of the rigidity of the suspension
over one link equals 1 (the elasticity of the suspension is uniform).
on this the conclusion can be made that the spatial rhombic catenary can
be used on high speed lines. On open line sections of a conventional
catenary for links of a standard length due to the necessity to extend
the supporting rods of messenger wires the horizontal dimensions of the catenary.
makes it necessary to install the catenary on horizontal consoles which
must be up to 5 meters long.
order to reduce the horizontal dimensions of the spatial catenary, rigid
stretching plates can be placed at the middle of the link between the
messenger wires. This makes it possible to reduce substantially the
horizontal dimensions while the vertical clearances of the catenary remain
unchanged. The stretching plates are of a pipe type profile to avoid a
building up of concentrated weights that would have a negative effect on
the dynamic behaviour of the catenary with links of a considerable length.
Two and even three such stretching plates can be installed. This makes it
possible to install the catenary with such horizontal dimensions which are
normally used to cover 50 or 30 meter long links.
spatial rhombic type of catenary is of a fundamentally new design. The
nature and the scope of possible damages that may occur with it is
presently being studied. Special destructive tests have been undertaken to
identify the nature of possible damages, the scope of the damage affected
zone and the time required to remove the damages.
case of disruption of one of the contact wires, like expected, the zone
affected by the damage was limited to one link only. The neighbouring
links on both sides showed minor changes in the positioning of the contact
case of disruption of one of the messenger wires the zone affected by the
damage was limited to one link only as well. In the neighbouring links the
positioning of the wires of the catenary practically did not change at all.
the course of operation of the spatial catenary disruptions of messenger
wires occurred. They happened at those places which had been damaged
during installation operations. The disrupted messenger wire was not
within the outer dimensions of the motive power and the catenary remained
operational. Train traffic as a matter of fact was not interrupted on
this section while the damage was removed.
of lines on which the spatial catenary is in operation for a long time on
and on the October railway regions show high
reliability under heavy traffic environment. Inspections and measurings
undertaken show that the status of the contact wires show no iocal wear,
nor any mechanical defects or burns.
a number of years of operation no adjustments were needed whatsoever. An 6
km long anchor section of the spatial catenary proved to be most reliable.
(The section can be seen in Fig. 4). At the moment arrangements are being
made to install an anchor section which will be 10 km long.
problems are involved in ensuring a trouble - free current collection
with conventional catenaries when trains are run with several pantographs
simultaneously in operation. In this case vertical oscillation of the
catenary initiated by the first pantographs affects negatively the
interaction with the catenary of the pantographs that follow.
monitoring of the interaction between the pantograph and the catenary of
the spatial rhombic type has shown that the fading of the oscillation
takes place much faster than with the conventional type of catenary. The
amplitude of oscillation is considerably smaller. While operating multiple
electric trains with 5 pantographs in a raised position at a time no
wire disruptions or sparkling were registered.
spatial rhombic type of catenary is much more wind resistant than the
conventional catenary and it is not subject to automatic oscillation.
Presently the work on designs is nearing completion for Ihe
electrification of a line exposed to such heavy winds which make it
impossible to use the conventional type of catenary even with a reduced
length of the links. On the same line a modified spatial catenary design
will be used to span a double track tunnel that had been built long ago
having limited vertical and horizontal clearances.
new tape of catenary is in operation for a long time already covering one
of the longest tunnels in the
that is a 8 km tunnel. The catenary in this tunnel
consists of a single anchor section. Each link of the section is 26 meters
long. In this case the vertical clearance is 400 mm. If the link is
reduced to 17 meters then the clearance may be as small as 200 mm.
runs with two electric locomotives coupled together with four pantographs
in a raised position have shown that the pressure stroke of the contact
wires does not exceed 50 to 60 mm. Trains are run on this section using
two twin-unit electric locomotives. Yet in the course of operation there
were no damages of Ihe catenary observed.
the future the spatial rhombic type of catenary will be used in tunnels in
this country. A project has been worked out to electrify the 15 km
Severo-Muyisk tunnel on the Baikal-Amur mainline using the spatial
catenary. The tunnel will be covered with a single anchor section without
providing cells for Ihe accommodation of anchors.
modifications of the spatial rhombic type of catenary have been developed
so as to be suitable for the installation in curves, on double track lines
as well as to meet other operational requirements. For instance, placing
the insulation in the fixing components of the suspension system makes
it possible to use the messenger wires as grounding wires, or wave guides
or as separate power lines.
utilization of the spatial rhombic type of catenary on mainlines
increases the reliability and the technical standard of the power supply
in one of its most important components.