Electric supply for a traction vehicle
The invention relates in general to the technical field of electric supply systems for railway traction
vehicles.
5
By convention, in the following text, the term "supply" should be understood to mean "electrical power
supply." Similarly, the terms "potential" and "current" are to be understood as meaning "electric
potential" and "electric current".
10 More specifically, the invention relates to an electric supply system specially intended for forming an
electric supply circuit able to supply power to a railway traction vehicle equipped with a pantograph,
based on an alternating electric current. The invention also relates to a railway system comprising
such a supply system and at least one track, and a railway assembly comprising such a railway
system and one or more traction vehicle(s).
15
In the technical field of supply systems, different solutions are known from the prior art for providing
sufficiently powerful electric current to supply power to railway traction vehicles in the most efficient
manner possible, regardless of their location relative to the electric traction substation or substations.
20 For example, there is a known supply system specifically intended for forming an electric supply
circuit that is able, from an alternating current, to supply a railway traction vehicle equipped with a
pantograph for its movement along a track, said supply system comprising an electric traction
substation or a plurality of electric traction substations distributed along the track, each substation
forming a supply sector comprising, along a linear distribution zone: a contact wire for carrying the
25 alternating current and for transmitting this alternating curient to the traction vehicle by friction of the
pantograph on the contact wire; a messenger wire positioned substantially in vertical alignment with
the contact wire and supporting said contact wire by means of a hanging structure; a negative supply
line having an offset position relative to the contact wire and to the messenger wire, and arranged in
the electric supply circuit so as to present an electric potential in phase opposition to the electric
30 potential of the contact wire; and possibly a positive supply line also having an offset position relative
to the messenger wire and arranged in the electric supply circuit so as to have the same electric
potential as the electric potential of the contact wire and of the messenger wire.
By convention, the supply lines are respectively designated as "positive" and "negative" because
35 their respective potentials are in phase opposition relative to each other, the reference being the
ground potential.
A supply system as defined above is known to the skilled person through the example given by
certain railway system embodiments which use the well-known technology called the "2x25 kV
standard" and in which certain supply sectors have linear distribution zones - in the vicinity of the
electric traction substations - where a supplemental positive supply line is optionally provided, said
line being positioned in the vicinity of the messenger wire in order to reinforce the power supplied in
the zones serviced by the electric traction substation.
5
In the technology of the 2x25 kV standard, the power is supplied by an electric traction substation
equipped with a transformer, connected at the primary side to the electric transmission grid and at
the secondary side to one or more supply sectors of the railway network in order to deliver a voltage
of 50 kilovolts. One terminal of the secondary side thus supplies power to the contact wire and the
10 messenger wire, and the other terminal of the secondary side supplies power to the negative supply
line, in phase opposition to the contact wire, to the messenger wire, and to the positive supply line
when the latter is present. In addition, the midpoint of the transformer's secondary side is connected
to the rail and to the overhead ground wire of the railway pack.
15 As mentioned above, in the 2x25 kV technology with a supplemental positive supply line, the supply
systems include a positive supply line in addition to the contact wire, the messenger wire, the
overhead ground wire, and the negative supply line. The electric potential of this supplemental
positive supply line is the same as that of the contact wire and of the messenger wire, which allows
withstanding the thermal aspects of the electric current in wires close to the traction substations.
20
But the technology of the 2x25 kV standard has disadvantages, as does the technology of the 2x25
kV with a supplemental positive supply line.
While it is true that the technologies of the 2x25 kV standard and 2x25 kV with additional positive
25 supply line have significantly improved the supply of power to railway traction vehicles by reducing
the impedance of the contact wire, developments in railway networks and electric transmission grids
are raising unresolved issues. More specifically, administrators of electric transmission grids are
facing economic and environmental constraints that are significantly reducing the possibility of
establishing facilities capable of supplying high input power to railway networks. Simultaneously, the
30 energy requirements of railway networks are increasing with the growing need to propel heavier
engines for freight applications, increase the acceleration of commuter trains to improve circulation,
increase the top speed of high-speed trains to reduce travel times, etc. As a result, the electric
traction substations are tending to be further and further apart, and the traditional technology of the
2x25 kV standard and of 2x25kV with a supplemental positive supply line no longer provide an
35 acceptable voltage quality at the pantograph in certain cases. In addition, with 2x25 kV with a
supplemental positive supply line, this line only provides compensation for the thermal load with no
significant positive impact on the quality of the power supplied when the electric traction substations
are far apart.
Also known from the prior art are other complementary supply systems based on the technology of
the 2x25 kV standard.
A first example is to use capacitors in series in the negative electric supply circuit of the railway
5 network. However, the operation of these supply systems is limited by the non-controllable
compensation of the impedances placed on the contact wire.
Another example is to add supplemental facilities consisting of a controllable capacitor circuit,
connected between the contact wire and the rails of the railway. Such systems are expensive and
10 fragile, however.
GB 2343431 concerns a system comprising two parallel tracks, thereby excluding the case of a
single track. According to the teachings of that document, the currents are balanced between the first
and second supply leads and the current is minimized in the return lead. This document does not
15 mention nor solve the problem of the lengthening of the sectors supplied by an electric traction
substation of a track equipped in this manner (compared to a 2x25 kV type system), or that of the
increasing distance between the electric traction substations for such a system.
Although patent SU 1562174 concerns 2x25 kV technology, its object seems to be a dual return
20 system. SU 1532361 appears to concern a 3 kV DC technology and its object seems to be a double
coaxial cable. Neither one is related to the problem of increasingly long substation supply sectors or
the increasing distance between substations.
The prior art also includes documents SU 1079494 and SU 1286450, which merely illustrate the
25 technological background.
In this context, the problem underlying the invention is to provide a supply system intended for
forming an electric supply circuit that is able, from an alternating current, to supply a railway traction
vehicle equipped with a pantograph for its movement along a track, said supply system being of the
30 type comprising an electric traction substation or a plurality of electric traction substations distributed
along the track, each substation forming a supply sector comprising, along a lipear distribution zone:
a contact wire for carrying the alternating current to power the vehicle via its pantograph; a
messenger wire supporting the contact wire by means of a hanging structure; a negative supply line
having an offset position relative to the contact wire and to the messenger wire, its electric potential
35 being in phase opposition to that of the contact wire; and a positive supply line that is offset relative to
the messenger wire, its electric potential being identical to that of the contact wire and of the
messenger wire;
which is generally without at least one of the limitations observed with the described prior art systems
of this type, and more specifically is such that, with no need for other accompanying equipment, it is*
possible, on the basis of an electric traction substation of a track equipped in this way, to lengthen
the supply sectors of the track equipped in this way, compared to known systems, and, for a plurality
of substations, to increase the distance between the substations of the track equipped in this way
and to improve the quality of the electric supply to the traction vehicle being moved on the track
equipped in this way (the meaning of "quality of the electric supply" having been previously
discussed).
Of course, the same problem exists for each track when there are multiple tracks.
The same problem exists for the entire track or for only a portion of the track.
A description follows of the invention as characterized in the claims.
The solution to the described problem consists, according to a first aspect of the invention, of having
the supply system arranged such that the position of the negative supply line is located between the
position of the positive supply line, which is always present, and the position of a geometric center
line positioned between the messenger wire (also referred to herein as "carrier cable") and the
contact wire, and such that the impedance of the electric supply circuit is reduced.
By this arrangement, the positive supply line advantageously provides the ability to act on the mutual
inductance of the phase-opposite supply lines and thus reduces the linear impedance of the electric
supply circuit of the track equipped with this supply system. Because of this, the substation of the
equipped track can feed longer supply sectors, and in the case where there is a plurality of
substations on the equipped track, the distance between the substations can be increased. This is
advantageous when installing new lines. Voltages to the pantograph can be improved for existing
lines as well. All these benefits are cumulative. In addition, it is possible to continue to use known
technologies such as the bare wires and insulators of 25 kV, which reduces installation costs while
accommodating all the types of messenger wire, substation, and connection to electric transmission
grids, both for existing lines to be reinforced and for new lines.
According to one characteristic of the invention, the position of the negative supply line is located
within a geometric ellipse having a major axis with a first end formed by the position of the positive
supply line and a second end formed by the position of the geometric center line. This arrangement
makes it possible to optimize the efficiency of the electric supply system.
In this case, according to one embodiment, the position of the positive supply line, the position of the
negative supply line, and the position of the geometric center line are substantially within the same
horizontal, oblique, or vertical geometric plane, which ensures optimum efficiency.
In one embodiment, the position of the positive supply line and the position of the negative supply
line are substantially in the same horizontal geometric plane, the position of the geometric center line
being vertically offset relative to the horizontal geometric plane.
5 In one embodiment, the position of the positive supply line and the position of the negative supply
line are substantially in the same vertical geometric plane, the position of the geometric center line
being horizontally offset relative to the vertical geometric plane.
In another alternative embodiment, the position of the positive supply line and the position of the
10 negative supply line are substantially in the same oblique geometric plane extending above or below
the position of the geometric center line.
In one embodiment, the position of the positive supply line and the position of the negative supply
line are vertically above the position of an overhead ground wire.
15
In one embodiment, the position of the positive supply line and the position of the negative supply
line are vertically above the position of the messenger wire.
The invention also relates, in a second aspect, to a railway system comprising a supply system as
20 above and at least one railway track.
The invention further relates, in a third aspect, to a railway assembly comprising a railway system as
described above and at least one traction vehicle arranged to be movable along the track and
equipped with a pantograph adapted to receive, by friction against the contact wire, an alternating
25 electric current.
We will now briefly describe the drawings of the figures.
Figure I a is a schematic representation of a supply system according to the invention, comprising an
30 electric traction substation and a supply sector having a linear distribution zone equipped with a
supplemental positive supply line.
Figure I b is a schematic representation of a supply system according to the invention, comprising
two electric traction substations supplying power to two supply sectors, one as an extension of the
35 other and each having a linear distribution zone equipped with a supplemental positive supply line.
Figures 2a and 2b are detailed schematic representations of a vertical cross-sectional vie; of two
embodiments of linear distribution zones that are part of a supply system according to the invention.
Figures 3a to 3c are detailed schematic representations of a vertical cross-sectional view of three
other embodiments of linear distribution zones that are part of a supply system according to the
invention.
5 A detailed description follows of several embodiments of the invention, particularly the supply system
10, with examples and references to the drawings.
By convention, the terms "horizontal", "vertical", "oblique", or "inclined" relate to the characteristics of
the electrical supply system, of the railway system, or of the railway assembly according to the
10 invention, when they are placed in their operative positions.
The supply system 10 does not only apply to a context of a 2x25 kV technology, but can also be
implemented with any other supply voltage andlor frequency, using a standard scheme with two
times the rated voltage with autotransformers. The supply system 10 can also be implemented in an
15 imbalanced scheme such as N kV, with n times N kV of voltage where n is not equal to 1 and N is not
equal to 25kV, using a scheme with autotransformers. Thus, although the following description
primarily concerns a 2x25 kV scheme, the supply system 10 is equally usable, by way of example
and not limitation, with a 2x20 kV scheme as in Japan, or an imbalanced sche1~7esu ch as 20 kV, 30
kV, etc.
20
The supply system 10 is intended to supply electrical energy to one or more traction vehicle(s) 12
equipped with a pantograph 14 or similar arrangement and capable of moving along a railway track
16 comprising rails 18.
25 In the context of the invention, the supply system 10 relates to a single track 16 intended for use and
able to function as such. In other words, the supply system 10 can function with a single track 16,
and does not require two parallel tracks.
Of course, it is possible to conceive of such supply systems 10 being associated with each
30 component track when there are several tracks. In the case of multiple tracks, it is possible that not
all tracks are equipped.
Moreover, the supply system 10 can be applied to the entirety of a railway track 16 or to only a
portion of the track.
35
To receive the electrical energy, the pantograph 14 of the traction vehicle 12 allows, by friction
against a contact hire (described below), using the electrical energy necessary to move itself and
one or more towed cars at acceptable speeds for the application concerned.
The supply system 10 can thus be used in the context of railway systems intended for high-speed
lines, commuter lines, rails used by freight cars, etc.
The supply system 10 is an improvement to the 2x25 kV standard technology, incorporating the basic
5 principles of this technology and applicable in all the traditional schemes, including those with a
power transformer having a midpoint as in the French scheme or a power transformer without a
midpoint but with autotransformers in the electric traction substations as in the scheme known in
Asia.
10 An embodiment of the supply system 10 illustrated in Figure l a will now be described in detail.
According to the technology of the 2x25 kV standard, the supply system 10 supplies electrical energy
to the railway network from the electric transmission grid. To do this, the supply system 10 comprises
an electric traction substation 20 or a plurality of electric traction substations 20 distributed along the
15 tracks 16 of the network.
Such an electric traction substation 20 has a transformer 22 connected at the primary side 22a to the
electric transmission grid and at the secondary side 22b to a supply sector 24 so as to form an
electric supply circuit providing the electrical energy required to operate the traction vehicle 12. The
20 supply sector 24 extends along a railway track 16 in a direction of movement Dp which coincides with
the direction of travel of the traction vehicle 12. This supply sector 24 may extend up to 40 kilometers
on loaded lines, and with the invention, up to distances of over 60 km.
The supply sector 24 firstly comprises a contact wire 34.
25
The contact wire is adapted to carry an alternating current to power the traction vehicle 12. This
contact wire 34 also extends along the direction of movement and has, in a preferred embodiment, a
phase at 25 kV potential.
30 The supply sector 24 also comprises a messenger wire 36.
The messenger wire 36 is at the potential of the contact wire 34, positioned st.tbstantially in vertical
alignment with the contact wire 34 and supporting said contact wire 34 via a hanging structure 38
(not shown in figures l a and I b). In other embodiments, the supply system 10 may also include, in
35 addition to the messenger wire 36, an auxiliary messenger wire (not shown) to facilitate and improve
the retention of the contact wire 34 in a horizontal plane.
The supply sector 24 further comprises an overhead ground wire 40.
The overhead ground wire 40 is arranged in the electrical supply circuit so as to ensure the electric
equipotential of all components other than the contact wire 34, the messenger wire 34, the negative
supply line (described below) and the positive supply line (described below), to the ground and to the
traction return. More particularly, this overhead ground wire 40 may be electrically connected to the
rails 18 of the railway track 16 and thus to the electrical ground so as to form the midpoint of the
electric supply circuit. Furthermore, this connection may be regularly repeated along the linear
distribution zone 30 in order to maintain the potential of the overhead ground wire 40 as equal to that
of the rails 18 of the track 16. Also, according to one embodiment, the overhead ground wire 40 may
additionally or alternatively be attached to support elements (described below).
The supply sector 24 further coniprises a negative supply line 42.
The negative supply line 42 is arranged in the electrical supply circuit so as to present an electric
potential in phase opposition to the electric potential of the contact wire 34 and of the messenger wire
36. Thus, the contact wire 34 has a voltage of 50kV with the negative supply line.
In the invention, the supply sector 24 has at least one linear distribution zone 30, corresponding to a
complete or partial section of the supply sector 24, in which a supplemental positive supply line 44 is
arranged as well.
The supplemental positive supply line 44 - which is only partially present in the supply sector 24 of
the embodiment illustrated in figure la - is distinct from the contact wire 34, the messenger wire 36,
the overhead ground wire 40, and the negative supply line 42, but is arranged in the electrical supply
circuit so as to have an electric potential that is identical to the electric potential of the contact wire 34
and of the messenger wire 36.
Therefore, when the contact wire 34 has a phase at 25 kV potential, the positive supply line 44 -
normally connected to a phase at 25 kV potential - is in phase with the potential of the contact wire
34 and of the messenger wire 36.
The supply sector 24 also comprises autotransformer terminals 46.
These autotransformer terminals connect the contact wire 34, the messenger wire 36, and/or the
positive supply line 44, to the negative supply line 42, in order to distribute evenly the voltages of the
contact wire 34, the messenger wire 36, and/or the positive supply line 44, on the one hand, and that
of the negative supply line 42. These autotransformers 46 are generally arranged every 6-15 km
along the supply sector 24. There can thus be, for example, up to seven autotransformers 46 per
supply sector 24.
Figure I b shows a supply system 10 according to the invention, comprising two electric traction
substations 20.
The first electric traction substation 20 is associated with a first supply sector 24 in which only part of
the linear distribution zone 30 is equipped with the supplemental positive supplj line 44.. The second
electric traction substation 20 is associated with a second supply sector 24 arranged as a
continuation of the first supply sector 24 and having a linear distribution zone 30 equipped with the
supplemental positive supply line 44 extending for the entire length of the second supply sector 24.
The first and second supply sectors 24 are then separated by a phase separation section 47.
The spatial arrangements of the component elements of various embodiments of a linear distribution
zone 30 that is part of a supply system 10 according to the invention are now described in reference
to figures 2a, 2b, 3a, 3b, and 3c.
First, as indicated above, the messenger wire 36 is positioned substantially in vertical alignment with
the contact wire 34 and supports said contact wire 34 through a hanging structure 38.
Next, the overhead ground wire 40 has a position that is horizontally andlor vertically offset relative to
the contact wire 34 and to the messenger wire 36 in order to comply with electrical safety distances
ensuring isolation according to current standards. In this regard, the overhead ground wire 40 may be
positioned above the messenger wire 36, level with the messenger wire 36, between the position of
the messenger wire 36 and that of the contact wire 34, level with the contact wire 34, or below the
contact wire 34.
Similarly to the overhead ground wire 40, the negative protection line 42 has an offset position
relative to the contact wire 34 and to the messenger wire 36. This negative supply line 42 may have
any horizontal andlor vertical position, meaning above the messenger wire 36, horizontally offset
relative to said messenger wire 36 so as to be level with said messenger wire 36, between the
messenger wire 36 and the contact wire, level with the contact wire, or below the contact wire. It is
also possible for the position of this negative supply line 42 to be located vertically above, below, or
level with the overhead ground cable 38.
The positive supply line 44 also has an offset position relative to the contact wire 34 and to the
messenger wire 36. More specifically and according to the invention, the position of the negative
supply line 42 is located between the position of the positive supply line 44 and the position of a
geometric center line 48 placed between the messenger wire 36 and the contact wire 34 so as to
reduce the impedance of the electric supply circuit. This arrangement increases the mutual
inductance between the negative supply line 42 on the one hand and the contact wire and positive
supply line 44 on the other hand, and acts to substantially reduce the impedance of the electric
supply circuit in comparison to conventional systems.
It is thus possible to supply power, from an electric traction substation 20 of a railway track 16
equipped with the supply system 10, to sectors 24 that are longer in the direction of travel while
maintaining a supply of electricity that is of good quality and is optimized for railway traction vehicles
12. Given the greater lengths of these supply sectors 24, the electric traction substations 20 of a
track 16 having a plurality of substations 20 and equipped with the supply system 20 may be far apart
from each other.
According to one characteristic of the invention, the position of the negative supply line 42 is located
within a geometric ellipse 49 where the major axis 49a has a first end formed by the position of the
positive supply line 44 and a second end formed by the position of the geometric center line. The
effect of the positive supply line 44 on the impedance of the electrical circuit is thus increased.
According to other even more advantageous embodiments, the position of the positive supply line 44,
the position of the negative supply line 42, and the position of the geometric center line are
substantially within the same horizontal, vertical, or oblique geometric plane. These embodiments
optimize the mutual inductance between the positive supply line 44 and the contact wire 34 and the
messenger wire 36, and thus further improve the quality of the electricity supplied while allowing the
electric traction substations to be further apart 20.
Figure 2a illustrates a first embodiment of a linear distribution zone 30 that is part of the supply sector
24 of a supply system 10.
In this embodiment, the position of the positive supply line 44 and the position of the negative supply
line 42 are substantially in the same horizontal geometric plane, while the position of the geometric
center line 48 is vertically offset relative to this horizontal geometric plane. The position of the
negative supply line 42 remains, however, within a geometric ellipse 49 having a major axis 49a
where the first end is formed by the position of the positive supply line 44 and the second end is
formed by the position of the geometric center line 48. The effects on the electrical impedance of the
electric supply circuit are thus optimized.
Figure 2b illustrates a second embodiment of a linear distribution zone 30 that is part of the supply
sector 24 of a supply system 10.
In this embodiment, the position of the positive supply line 44 and the position of the negative supply
line 42 are substantially within the same oblique or inclined geometric plane extending substantially
toward the position of the geometric center line 48. Thus, the positions of the positive supply line 44,
the negative supply line 42, and the geometric center line 48 are within the same oblique geometric
plane.
More particularly, in the present case the position of this positive supply line 44 is located vertically
5 above the position of the negative supply line 42, which in turn is located above the position of the
geometric center line 48.
In other embodiments, not shown, the oblique or inclined geometric plane formed by the positions of
the positive supply line 44 and negative supply line 42 could extend above or below the position of
10 this geometric center line 48.
Similarly, regardless of the relative vertical positions of these positive 44 and negative 42 supply
lines, the positive 44 and negative 42 supply lines can have any vertical position, namely above the
messenger wire (36), level with the messenger wire (36), between the messenger wire (36) and the
15 contact wire (34), level with the contact wire (34), or below the contact wire (34). It is also possible for
said positive 44 and negative 42 supply lines to be positioned in any vertical position, namely above,
below, or level with the overhead ground wire.
Figure 3a shows a third embodiment of the invention.
20
In this embodiment, the position of the positive supply line 44 and the position of the negative supply
line 42 are substantially in the same vertical geometric plane extending substantially toward the
position of the geometric center line 48. Thus, the positions of the positive supply line 44, negative
supply line 42, and geometric center line 48 are all within the same vertical geometric plane.
25
More particularly, in the present case the position of this negative supply line 42 is located vertically
above and in alignment with the position of the positive supply line 44, which itself is located above
and in alignment with the position of the geometric center line 48.
30 In alternative embodiments, the position of the positive supply line 44 and the position of the negative
supply line 42 could be substantially within a same vertical geometric plane, and the position of the
geometric center line 48 could be slightly offset horizontally relative to this vertical geometric plane.
Figures 3b and 3c represent two other embodiments of the invention.
35
In these embodiments, the position of the positive supply line 44 and the position of the negative
supply line 42 are substantially lbcated above the geometric center line 48, within the same oblique
geometric plane - in one direction or the other - extending substantially toward the position of the
geometric center line 48. Thus, the positions of the positive supply line 44, negative supply line 42,
and geometric center line 48 are all within the same oblique geometric plane.
In other embodiments, not shown, the oblique geometric plane formed by the positions of the positive
supply line 44 and negative supply line 42 could extend above or below the position of the geometric
center line 48.
Moreover, as the linear distribution zone 30 extends over several kilometers, this zone comprises a
plurality of support elements 50 arranged, for example, approximately every sixty meters, mounted
vertically and intended to support the contact wire 34, the messenger wire 36, the overhead ground
wire 38, the negative supply line 42, and the positive supply line 44.
These support elements 50 are arranged close to the railway track 16 and may have a height
generally and usually between 6 and 12 meters.
More particularly, as illustrated in figures 2a to 3c, the positive supply line 44 and the negative supply
line 42 are permanently attached, directly or indirectly, to an upper end 54 of the support element 50,
while the overhead ground wire 38 is arranged on the mid-section of the support element 50. The
positive 44 and negative 42 supply lines are supported by the support element 50 so as to be spaced
apart from each other transversely by a distance of between 0.5 m and 2 meters or other values
depending on the supply voltages.
In addition, the support element 50 has a support arm 56 extending in a transverse direction DT
substantially perpendicular to the longitudinal direction of advancement Dp of the linear distribution
zone 30. The support arm 56 supports the messenger wire 36 above the track 16, said messenger
wire supporting the contact wire 34.
However, these support elements 50, well known to those skilled in the art, could be replaced by any
other arrangement which allows obtaining the spatial distributions described above.
The supply system 10 obtained, which provides a reduced impedance compared to known systems
of the same type, allows supplying power from a substation 20 to a railway system with longer supply
sectors 24 and allows spacing the electric traction substations 20 further apart, which allows
supplying the electric supply circuit using the AC current originating from the electric transmission
grid, for a distance that can exceed 60 km in the longitudinal direction of travel of the linear
distribution zone 30, even when the railway track 16 has heavy traffic.

Claims
1. Supply system (10) specially intended for forming an electric supply circuit able, from an
alternating electrical current, to supply power to a railway traction vehicle (12) equipped with a
pantograph (14) for its movement along a railway track (16), said supply system (10) comprising an
electric traction substation (20) or a plurality of electric traction substations (20) distributed along the
track, each substation (20) forming a supply sector (24) comprising, along a linear distribution zone
(3 0) :
m a contact wire (34) for carrying the alternating current and for transmitting this alternating current
to the traction vehicle (12) by friction of the pantograph (14) on the contact wire (34);
a messenger wire (36) positioned substantially in vertical alignment with the contact wire (34) and
supporting said contact wire (34) via a hanging structure (38);
a negative supply line (42) also having an offset position relative to the contact wire (34) and to
the messenger wire (36), and arranged in the electric supply circuit so as to present an electric
potential in phase opposition to the electric potential of the contact wire (34);
a positive supply line (44) also having an offset position relative to the messenger wire (36) and
arranged in the electric supply circuit so as to have the same electric potential as the electric
potential of the contact wire (34) and of the messenger wire (36);
characterized in that:
m the position of the negative supply line (42) is located between the position of the positive supply
line (44) and the position of a geometric center line (48) positioned between the messenger wire (36)
and the contact wire (34),
the impedance of the electric supply circuit of the track equipped in this manner being reduced,
such that, for an electric traction substation (20) of the track so equipped, the supply sectors (24) of
the track may be longer, and such that for a plurality of electric traction substations (20) of the track
so equipped, the distance between the substations (20) can be longer, while improving the quality of
the power supplied to the traction vehicle (1 2) moving on the track so equipped.
2. Supply system (10) of claim 1, wherein the position of the negative supply line (42) is located
within a geometric ellipse (49) having a major axis (49a) with a first end formed by the position of the
positive supply line (44) and a second end formed by the position of the geometric center line (48).
3. Supply system (10) according to claim 2, wherein the position of the positive supply line (44), the
position of the negative supply line (42), and the position of the geometric center line (48) are
substantially within the same geometric plane.
4. Supply system (10) according to claim 3, wherein the geometric plane is horizontal, vertical, or
oblique.
.., . J 1 - PCT/PR2012/051719
14 Q 1054fiPl@
5. Supply system (10) according to either of cla~ms 1 or 2, wher he os~tion of the positive
supply line (44) and the position of the negative supply line (42) are substantially in the same
horizontal geometric plane, the position of the geometric center line (48) being vertically offset
relative to the horizontal geometric plane.
5
6. Supply system (10) according to either of claims 1 or 2, wherein the position of the positive
supply line (44) and the position of the negative supply line (42) are substantially in the same vertical
geometric plane, the position of the geometric center line (48) being horizontally offset relative to the
vertical geometric plane.
10
7. Supply system (10) according to either of claims 1 or 2, wherein the position of the positive
supply line (44) and the position of the negative supply line (42) are substantially in the same oblique
geometric plane extending above or below the position of the geometric center line.
15 8. Supply system (10) according to any one of claims 1 to 7, wherein the position of the positive
supply line (44) and the position of the negative supply line (42) are vertically above the position of
the messenger wire (36).
9. Railway system comprising a supply system (10) according to any one of claims 1 to 8 and at
20 least one railway track (1 6).
10. Railway assembly comprising a railway system according to claim 9 and at least one traction
vehicle (12) arranged to be movable along the railway track (16) and equipped with a pantograph
(14) adapted to receive, by friction against the contact wire (34), a supply alternating electric current.