SELCAB

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SELCAB is a linear train control system derived from the LZB . It was developed at the beginning of the 1990s by Standard Elektrik Lorenz (SEL) with a special focus on routes with low to medium traffic. The interface between vehicle and track is fully compatible with LZB ( UIC standard ORE A46) and identical on-board devices can be used for both systems. Correspondingly, driver's cab signaling is provided by the system, an operating mode that approximates the moving block can be implemented, and the automatic driving and braking control (AFB) is supported.

In contrast to LZB, however, there are no central computers that monitor a route in sections, but the influences are generated decentrally from the data from existing facilities (mainly signals). Conceptually, this idea of quasi-continuous influencing at ETCS Level 1 Limited Supervision was later taken up again in a similar way. At its creation SELCAB was in direct competition with the parallel of Siemens developed ZUB 100 .

Trackside facilities

On the line side, 64 (2 6 ) different telegrams with 70 bits of user data each  can be transmitted. The transmission of a single telegram takes 70  ms (1200  Bd ), with such packaged information being repeated four times in normal operation, resulting in an effective cycle time of 280 ms. The telegrams are then FSK- modulated and transmitted in the long wave range (36  kHz ± 600 Hz). The data on which the telegrams are based are typically tapped directly from the lamp circuit of a signal and then processed using a logic circuit. However, a direct connection to a signal box is also possible. Multi-section signaling can thus also be implemented.

The telegrams contain the following information:

  • Signal aspect
  • currently permitted maximum speed
  • Distance to the stop
  • Slip path at the breakpoint
  • Slope
  • permanent and (optional) temporary speed limits
  • other special conditions

Optionally, temporary speed restrictions can also be transmitted to the vehicle using SELCAB. However, this requires additional line-side modules and halves the fourfold redundancy described above for the transmission of telegrams.

Similar to the LZB, crossed line cables , which are laid in sections in the track, are used for data transmission. The system supports loop lengths from 25 m to 1200 m. The length has an influence on the maximum train density and, due to the transmission time (see above), also on the maximum speed of the corresponding route section. To differentiate the direction of travel, two partial loops are required for each signal, one of which is laid in front of and one behind the signal. Only for the former are different lengths projected depending on the desired line performance, and it therefore largely determines the above. Total loop length.

On-board facilities

As described above, SELCAB can be used with an LZB vehicle equipment (LZB 80). In this case, however, the transmission device is not absolutely necessary, since data transmission from the vehicle to the route is not provided by the system. To reduce costs and space, instead of the LZB vehicle computer, which is typically designed in a 2v3 configuration, a simplified 2v2 device can be used, which is used in particular in local traffic. The central processing unit is called VOBC (Vehicle On-Board Computer). The software functions are implemented in Pascal and assembler .

In addition to this computer, two wheel pulse generators, an acceleration sensor to compensate for slip-related measurement errors and two (or four for bidirectional vehicles) receiving antennas must be provided on the vehicle . In addition, a safe control option for the automatic brake is required.

Before starting a journey , the driver must enter the following parameters using a pushbutton-based control unit with a display :

  • Train length
  • Maximum train speed
  • Train braking properties

A display device (see MFA ) will thereupon

  • Maximum permissible speed / actual speed on a two-pointer speedometer
  • Target speed
  • Target range
  • Help displays

and the vehicle system continuously monitors the following variables:

  • Line speed
  • Breakpoint
  • Direction of travel / roll back against the selected direction of travel
  • dynamic braking profile
  • Speed ​​limits
  • Crossing a signal indicating a stop

In addition, the vehicle equipment consists of two control buttons for releasing the service brake and for passing a non-permissive signal aspect (see command ). Warnings and brake announcements can be sent to the driver via acoustic alarms. A tachograph is available to record events.

use

SELCAB is installed on the new Madrid – Seville line as an extension of the LZB in station areas . There is also an installation on the section of the Chiltern Line between London Marylebone and Aylesbury in the United Kingdom . In other networks (including the ÖBB in Austria ), however, it never got beyond test applications to this day. Nevertheless, the system can be seen as a pioneer of the Euroloop transmission medium used for ETCS .

Thales continues to sell the system under the name AlTrac 6431 today .

In relation to ETCS, SELCAB is a class B system.

literature

Individual evidence

  1. ^ Norbert Geduhn: Implementation Concepts from Siemens . In: signal + wire . tape 84 , no. 12 . Tetzlaff Verlag GmbH, 1992, ISSN  0037-4997 , p. 397-399 .