01. April 2016

New developments in inter-car jumpers

For multiple-unit trains, it is imperative that each car be reliably and safely supplied with the electrical lifelines of power, signals and data. Laying electrical cables in the car itself is not a problem since they lie protected in the floor or roof assembly. However, the transition cables or “jumpers” to the next car are exposed to high mechanical stresses that result from bending, stretching and twisting. Similarly, any cables which are mounted externally are subjected to a broad range of environmental conditions such as UV radiation, heat, cold, rain, ice and snow.

Ethernet communications

Ethernet communications links are now being used widely both within trains and for inter-car connections. The first generation of these interconnectivity solutions were developed to link systems for functions such as passenger information, entertainment, security (e.g. CCTV) and automatic passenger counting, and were largely based on 100 Mbit/s Ethernet technology running over Cat.5 cabling. 

As both communication technology and the economic and regulatory needs of the marketplace have evolved, there is now a need for further expansion in the capabilities of these networks, with additional capacity needed to meet the requirements of advanced train control systems such as ECTS (European Train Control System), driver-only operation, train-wide data monitoring, and new public access services such as Wi-Fi. More significantly, in many cases there has to be clear physical separation between critical and non-critical networks, so that systems responsible for train control and safety functions are fully protected against potential cyber attacks via the public access network.

In performance terms, current Ethernet networks on board trains are operating at 100 Mbit/s and 1 Gbit/s because this is the maximum practicable speed that can be achieved with the current generation of Ethernet switches. However, train manufacturers are looking to the future, so all new designs are specifying 10 Gbit/s to allow for the higher speeds that will result from technological developments and the requirements of new applications.

HARTING has developed an integrated modular solution that addresses the challenges outlined above as well as providing “future-proofing” for the next generation of trains (Fig.1).

The HARTING solution for these applications is based on an “open” Han® 24 HPR hood and a range of inserts from the Han-Modular® industrial connector family (Fig.2). The standard HPR housing has been approved by the rail industry and is already in use in the field. A threaded locking mechanism enhances stability and provides good protection against shock and vibration. Strain relief is achieved with a strain relief clip or a corrugated conduit adapter with strain relief. Shielding from several cables can be attached to shielding rings or clamping brackets to reduce cost. Instead of using bulkhead or surface-mounted housings, the interface at the car end is screwed directly onto a mounting plate, which results in a significant reduction in cost and weight.

The result is a fully preassembled and tested inter-car connection, pluggable from both sides by using the open hood (Fig.3). HARTING also supplies mounting plates which are attached to the walls of the cars. Han-Modular®, Han Quintax® and Han® EEE inserts in Han® HPR upper and lower housings are fitted onto the power and signal cables which are routed through corrugated plastic conduit. In some cases, top-entry upper housings are used which mate with lower housings that are mounted on existing angle plates to optimise cable routing. The wires are protected inside the conduits to minimise the risk of abrasion. A pivoting threaded conduit connection is used to accommodate the dynamics of the application.

Interference must be avoided between the power and signal lines which are routed very close to each other. In fact, the electromagnetic interference immunity of this system has been demonstrated during system testing.

Future-proofing

These robust jumper cables and customisable connectors provide sufficient bandwidth to allow expansion to accommodate the demands of future higher-performance communication networks. Using HARTING Han® HPR connectors with ground disconnect, these solutions provide full 10 Gbit/s transmission tested to IEEE 802.3. They are compliant with fire regulation EN 45545 – 1, 2 & 5 and EN 50155:2007 to ensure reliable application on rolling stock, and offer industry-leading IP68 (submerged under pressure) and IP69K (high-pressure steam lance) sealing capability.

HARTING also carries IRIS certification to meet the stringent demands of the rail industry. This includes certification to IRIS Version 02 which covers trackside use as well as on rolling stock.

The modular nature of the Han® HPR family gives users the ability to mix signal, data and power interfaces in a single connector, along with the flexibility to incorporate up to six 10 Gbit/s links in the connector.

RFID transponders

A recent development is the use of connectors fitted with industrial-grade Ha-VIS RFID transponders (Fig.4). These transponders are extremely robust and can accompany the product from manufacturing through the broad variety of railway vehicles’ maintenance intervals all the way to replacement.

The transponders permit the unique identification of the jumpers and monitor the maintenance history error-free throughout the entire life cycle. This enables the precise analysis and classification of wear and tear, as well as the identification of errors and their source. In this way, Han® connectors with RFID support both product traceability and the integration of state-oriented maintenance of rolling stock. The result is an overall saving in time, money and life cycle costs.

HARTING Integrated Solutions

The modular Gigabit jumpers have been developed and manufactured by HARTING Integrated Solutions: a division of the company that designs and manufactures backplanes and backplane systems as well as customised cable assemblies for a wide range of applications. The group's activities range from design simulation and validation to comprehensive system testing.

For the rail industry, HARTING offers a complete range of design and build solutions with the emphasis on saving space and weight. In addition to connectivity products covering high-speed data transmission at speeds of 40 Gbit/s or more, HARTING has developed a number of techniques for providing power to PCBs on board trains, on platforms or on the trackside (Fig.5).

A common challenge in the rail industry is presented by high currents routed in proximity to sensitive PCB signal paths, which can cause problems in terms of PCB design and thermal management. HARTING offers the expertise to overcome these issues by developing custom backplanes and passive PCBs.

A typical recent rail project handled by HARTING was the development of a rail (EN 50155) approved chassis for an embedded drive controller at lower cost than the existing customer product. For this application, HARTING developed a custom backplane, I/O and chassis.

Another major project was the replacement of a hard-wired relay rack for Vossloh’s Euro 3000 locomotive with a backplane-based solution offering lower cost, easier maintenance and enhanced flexibility as well as weight saving.

HARTING Integrated Solutions is active as a fully integrated system developer and manufacturer, including production. Operating a global manufacturing footprint, the company has factories on three continents: Europe, Asia and North America. Each site has common equipment, tooling and procedures to provide seamless service to all global customers.


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