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Our progress with trials in the oscillation damping

We have managed to dampen the wave in less than 8 seconds, a record, and for a year the improvements have been 100%. The weight of the Inoviria CaDOD-100 is less than 5 Kg and is compensated by the presetting of the fall in the center of the opening that can be regulated thanks to the Innoviria CaDOD-100.

The following figure shows the comparison in the response for a catenary span of 9 meters subjected to a manual excitation that introduces an initial energy representative of the one that would incorporate the step of a pantograph to the span analyzed. The difference in response is observed for the same vain, incorporating or not the Innoviria CaDOD-100. The oscillation for the catenary with the Innoviria CaDOD-100 (lower graph) stops before 8 seconds, while for the same catenary without the device (upper graph), the oscillation is maintained for more than 1 minute.

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Improvements that Innoviria brings to the rigid catenary

The rigid catenary together with the conventional or flexible catenary are the two most widespread mechanical systems in the aerial transmission of electric current to the train. The flexible catenary is a system with three clear advantages compared to the rigid catenary. These are:

  • Operating speed limits in higher trains (350 km / h).
  • Minor displacements (natural fall) in the center of the span.
  • Greater lengths between supports (spans of up to 60 m).

These three characteristics, among other aspects, favor the current installation of more kilometers of flexible catenary than of rigid. The design of the flexible catenary adapts perfectly to most railway infrastructure scenarios. However, the rigid catenary is a system with some very interesting advantages, which are:

  • It is easy to install because of the type of supports.
  • They allow the replacement of the contact wire semiautomatically.
  • It has a greater section of electrical conductivity and greater possibility of evacuation of heat in the case of some point and momentary overcurrent.
  • It requires smaller gauges than the flexible catenary.
  • It does not require prestressing like the flexible catenary.

All the above characteristics make the rigid catenary a simple device, robust in its operation and very reliable from the point of view of safety. These aspects are fundamental in tunnel installations where the obligatory stop of a train, for reasons of a flexible catenary break or other event, would suppose a security problem, which would be aggravated in case of needing the evacuation of the passengers inside the tunnel . These are the reasons why the rigid catenary is widely used in tunnels for metropolitan and suburban railway infrastructures. This use is spreading more and more and regional infrastructure projects are being initiated, and it is even being studied to incorporate it into sections of higher speeds.

The advantages provided by the rigid catenary are making it gain ground against the flexible catenary and more and more railway administrations are opting for this option. The power of the rigid catenary seems to be still to be discovered, although it is already beginning to take off.

These expectations of growth are slowed down by the limitations in speed of operation, by the shorter lengths between supports required and by the excessive central fall when the supports are separated from each other to make the infrastructure cheaper. All these aspects are solved by Innoviria with its novel and proven device.

With the Innoviria CaDOD-100, the rigid catenary design is optimized allowing:

  • regulate the damaging central fall of the rigid catenary and the center of the spans,
  • increase the speed of operation by improving the dynamic behavior of the rigid catenary, and
  • lower the costs of the infrastructure due to the possibility of increasing the length of the bays.

The following figure shows the difference in the contact force between the rigid catenary and the pantograph for a usual situation (Before) and its difference when incorporating the Innoviria CaDOD-100 (After). Which regulates the positioning of the catenary and controls unwanted vibrations.

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Figure 1. Contact force between rigid catenary and pantograph.

The graph in the upper part of figure 1 shows three undesirable phenomena in any catenary design. The excessive oscillations of the sections between mechanical cantons generate large oscillations that lead to:

  • excessive wear due to maximum force values,
  • electric arcs in the values ​​close to 0 N of contact force, and
  • greater values ​​of standard deviation in the contact forces that is related to the wear of the wire and the tables of the pantograph.

All the undesirable phenomena are reduced or disappear when the Innoviria CaDOD-100 is installed (lower graph of Figure 1), which controls the vibrations and allows, in summary, lower maintenance costs and greater operational safety. In addition, the smaller oscillations generated in the contact forces, improve the interaction between the catenary and all the pantographs for operations with multiple pantographs.

Catenary rigid comparisons with our invention

Many clients before talking with us ask us how our system CaDOD-100 behaves in its catenary, for that we have had to make reports, we are going to publish them here on our website:

Comparison of the static and dynamic behavior of the PAC110 Delachaux profile with Innoviria CaDOD-100 device.

This report shows the comparison of the results of mathematical models of finite elements for two different systems of Rigid catenary: Profile PAC110 of Delachaux with and without Innoviria CaDOD-100 device. In addition to this comparison, the comparative of a representative case of the MM14 profile of Metro Madrid is presented at the end of the report.

1.- Content of the report

The report includes a brief description of the Innoviria CaDOD-100 device, the comparison of the static stiffness behavior, the comparison of the natural frequencies of resonance, the comparison of the dynamic behavior before the passage of a standard pantograph, the effect of the increase in temperature and , to finish, the effect of improvement in the static rigidity of the MM14 profile of Metro Madrid.

2.- Description of the CaDOD-100 device

The CaDOD-100 device, which is shown in figure 1, consists of 4 parts essentially:

  • a normally hollow and light profile that is positioned parallel to the catenary profile and above it at a controlled height (hereinafter referred to by the letter “H”),
  • two supports that allow connecting the ends of the upper hollow profile with the catenary profile (hereinafter referred to as “L”), and
  • an adjustment system that allows to precompress the upper hollow profile to properly elevate and align the rigid catenary profile.

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Figure 1: CaDOD-100 device on profile PAC110 by Delachaux

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Figure 2: Preload necessary in Innoviria CaDOD-100 device

To complete the description of the device, figure 2 shows the necessary forces of precompression to align a profile PAC110 placed in all the spans of 10 meters of a canton of 300 meters in total length. The figure shows how the necessary preload depends on the height at which the upper hollow profile of the CaDOD-100 is positioned. At a lower height, a higher preload is necessary. The calculations shown in the figure have been made for a length of invention L = 5.2 meters and a hollow profile of 80 x 80 x 2 mm in aluminum.

3.- Comparison of the stiffness in the center of the span

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Figure 3: Rigidity in center of span for different sections of the CaDOD-100

Figure 3 shows the vertical rigidity of the center of bay number 18 in a canton of 300 meters with spans of 10 m. The figure shows in black the stiffness value for the PAC 110 profile. Also shown in blue and red is the stiffness variation for the PAC 110 profile with CaDOD-100 of L = 5.2 m in length installed with three different tubes of square section ( 100x100x2mm, 80x80x2mm and 60x60x2mm).In the figure it is observed that:

  • The Innoviria CaDOD-100 device placed on the Delachaux profile increases its rigidity in all its configurations of different heights, from 46% for a device height of 0.1 m to 388% for a height of 0.5 m.
  • No significant influence on stiffness is observed for the variation of the three different sections of the upper tube of the device.

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Figure 4: Rigidity in center of span for different lengths of the Innoviria CaDOD-100 

Figure 4 shows the vertical stiffness that the same vain 18 has in its center for a canton of 300 meters with spans of 10 m. The stiffness value for the PAC 110 profile is again observed, as well as the variation of stiffness for the PAC 110 profile with CaDOD-100 where the section of the tube is now kept constant at 80x80x2mm and the length of the device is modified with measures of 3.2, 5.2 and 7.2 meters. It is observed that:

  • The variation of the length of the absorber CaDOD-100 significantly influences the rigidity, presenting a higher value in the case of length 5.2 meters, compared to the other cases studied.
  • Increasing or decreasing the length of the CaDOD-100 device in the same proportion does not modify the final stiffness in that same proportion.
  • There is, therefore, an optimum for the length value of the invention. This maximum is in accordance with other parameters of the absorber CaDOD-100.

4.- Comparison of natural frequencies

In the field of dynamics, the natural frequencies of mechanical systems are a fundamental element to know the behavior of the system under study when it is subjected to variable loads over time. The natural frequencies are related to the rigidity that a system presents during its deformation phase in the vibration. It is also known that in the vibratory phenomena of mechanical systems most of the energy in play is absorbed by the modes with the lowest natural frequencies. This last aspect is the reason that the rigid catenary present oscillations at low frequencies that last over time and take time to muffle.

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Figure 5: Comparison of natural frequencies

Figure 5 shows the first 30 natural frequencies for the same canton as in the previous sections. It is observed that:

  • The Innoviria absorbers CaDOD-100 placed on the PAC 110 profile increase the natural frequencies in all its height configurations.
  • The modes with the smallest values, which are the most influential in the final vibratory response, are those that increase the most.

5.- Comparison of responses in time before the passage of a pantograph

This section shows the response of the canton modeled during the interaction of a standard pantograph (UNE-EN-50318) circulating at 110 km / h. The contact forces between the table and the contact wire, the oscillations of the catenary and the oscillations of the hollow profile of the absorber CaDOD-100 while the pantograph covers the entire section are shown. null

Figure 6: Comparison of contact forces

Figure 6 shows the contact force between the pantograph and the catenary for the same situations presented in the previous sections, that is, for the PAC110 profile and for the PAC110 with CaDOD-100 devices installed at different heights. All the vertical axes show force values ​​in Newtons and the horizontal axes correspond to the position that the pantograph has at all times along the canton. In all cases, the standard deviation of the forces has been noted, which are related to the wear of the contact wire. It is observed that:

  • In all cases, a greater excitation is generated at the entrance of the pantograph in the canton, a phenomenon that is also identified in reality.
  • The standard deviation in the contact force of the PAC110 profile with absorbers CaDOD-100 show significantly lower values ​​for all heights.
  • For an absorber CaDOD-100 height of H = 0.1 m the contact force is reduced by 35% and for a height H = 0.3 m the reduction reaches 52%.
  • The improvement in the life of the contact wire and the pantograph could be considerable .

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Figure 7: Comparison of the oscillations in the center of span 18

Figure 7 shows, for the same conditions and with the same interpretation of its axes as in the previous case, the vertical oscillation of the center of bay 18. It is observed that:

  • In all cases the PAC110 when the Innoviria CaDOD-100 device is installed decreases the oscillations.

Figure 8, on the next page, shows in the same circumstances as the previous two the oscillation of the center of the absorber CaDOD-100 placed in span 18 of the section. It is observed that:

  • As the height of the device decreases, the oscillation increases, since it must work more in order to control the vibration of the PAC 110.

nullFigure 8: Comparison of the oscillation in the center of the Innoviria CaDOD-100 device

6.- Study of the effect of temperature

The rigid catenary is installed mostly in tunnels, where the temperature can increase substantially. Using the canton models of the previous sections, the study has been contemplated for two representative cases of the PAC110 profile with absorbers CaDOD-100 installed in two heights: at 0.3 meters (as a representative case) and at 0.1 meters height (as a limit case). Figures 9 and 10 show the results of the contact force and the oscillation of the center of the third bay of the canton. It is observed that:

  • There are no substantial differences in the analyzes between the temperature of 20º and 60º.
  • It is not expected that the temperature is therefore no problem.

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Figure 9: Contact forces. Effect of temperature

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Figure 10: Oscillation in center of span 3. Effect of temperature

7.- Comparison of profiles PAC110 and MM14

Once the behavior between the PAC110 and PAC110 systems with Innoviria CaDOD-100 has been compared, it seems interesting to ask how the MM14 profile behaves.

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Figure 11: Stiffness in the center of the span for the profile PAC110, MM14 and PAC 110 with CaDOD-100

Figure 11 shows the stiffness in the center of the span for the profile PAC110, MM14 and PAC 110 with CaDOD-100 at different heights. It is observed that:

  • The MM14 profile shows greater rigidity than the PAC 110, as expected since it has an inertia 72% greater than the PAC 110.
  • The PAC 110 profile with Innoviria CaDOD-100 has much higher values ​​than the MM14 profile. The PAC 110 profile with CaDOD-100 at H = 0.3 m almost duplicates the rigidity of the MM14 profile.

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Figure 12: Natural frequencies. Comparison with profile MM14

Figure 12 shows the natural frequencies for the profile PAC110, MM14 and PAC 110 with Innoviria absorbers placed at 0.3 meters height. It is observed that:

  • The MM14 profile shows higher frequencies than the PAC 110, as expected since it has an inertia 72% greater than the PAC 110.
  • The PAC 110 profile with Innoviria absorbers presents frequency values ​​in low modes up to 21% higher than the MM14 profile.

8.- Conclusions of the studies

From the comparative study presented, according to the results of the mathematical models developed, for profiles PAC110, MM14, PAC110 with Innoviria CaDOD-100 absorbers, we can conclude that:

  • In all cases , for the static and dynamic behavior , whenever the Innoviria CaDOD-100 device is incorporated, the behavior is improved, reducing the contact forces and the vibrations of the catenary. The decrease in contact force reduces contact wire wear and wear on pantograph tables. The decrease of the vibration in the catenary improves the contact of the pantographs that travel in second position for units in double or even triple configuration.
  • The incorporation of the Innoviria CaDOD-100 absorber on the PAC110 profile offers greater static rigidity than the MM14 profile.
  • The incorporation of the Innoviria CaDOD-100 absorber on the PAC110 profile offers higher natural frequencies than those with the MM14 profile.
  • The temperature does not substantially affect the vibrations or the contact forces.