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Rugged and reliable connectivity for safety-critical applications

Train deceleration is a key function that implies passengers’ safety, environment and property protection and nothing can be left to chance or neglected when it is the moment to select the right parts that have to compose the brake system. With this in mind, the design engineers have to pay attention to reduce the overall maintenance costs as well to provide a dependable and market aligned solution. The way to the right solution is long and will never probably ends as the technological evolution of the rail market follows the continuous flow of the human and science progress.

Connectivity can play a key role rail braking systems
Connectivity can play a key role rail braking systems

Safety-critical applications are those where if systems fail, they can cause loss of life, significant property damage or damage to the environment. These applications can be found in different segments of the industry such as medical devices, aircraft flight control, nuclear systems, automotive and transport sectors. The railway industry is not an exception.

Safety-critical systems are often exposed to high vibrations and extreme temperatures and therefore they need reliable and robust components to achieve the necessary performance, system qualifications and customer confidence to reach satisfactory technical and sales results. Normally the products supplied to this industry are classed as ‘safety critical’ items and therefore must conform to specific Rail Standards for Safety Critical Items.

Background

Braking systems are among the sensitive applications that require a reliable design, and their components must work under extreme temperature, mechanical shock and vibration, difficult access, water or dirt and dust ingress, and fretting corrosion. It’s a tall order. Electrical connectors are part of this challenging design and have to withstand all these different challenges and assure precise operating performance and proper brake cylinder pressure under all braking condition.

Of course, the combination of superior technical features of the connector is essential to reach this demanding result and solve the system manufacturers’ requirements. In general, when the application is vital for the users’ safety, in this case passengers, each single product composing the system has to provide tested superior performances and meet the design and operational demands​. The connectors have to be made or robust materials to provide enhanced resistance to fretting wear when exposed to severe vibration, have to provide a long service life​ and a stable electrical signal.

The Challenge

One leading global company of equipment, systems, and value-added services for the freight and transit rail market segments turned to Smiths Interconnect for a solution that could operate under all braking conditions.

In addition to ensure safety, they required that the design of the connectors had to be able to follow the industry trends and to develop the sustainable solutions required by the market and, last but not least, reduce the cost of maintenance by supplying durable solutions

C Series Connectors

The Solution

C series connectors, a family of EMC Metallic Circular Connectors, have been designed keeping in mind all the above-mentioned requirements and preambles. The series, featuring Hypertac Hyperboloid contact technology, is an IP67 circular connector with an EMC metal housing suitable for automatic train, operation and traffic control and in particular for sensors in train braking systems as they resist under the most extreme environmental conditions.

Product Details

These connectors can offer robust sealed body shells with mechanical keying systems to ensure safe mating, cable clamps with large cabling chambers to allow various cable diameters and shielding for EMI and RFI protection. They can also typically be ordered as cable assemblies to provide a complete interconnect solution with low costs of maintenance.

Their technical features assure precise operating performance and proper brake cylinder pressure under all braking condition and the metal alloy that composes the connector body provides enhanced resistance to fretting wear when exposed to severe vibrations.  The cost-effectiveness comes from C-series connectors lasting longer being made from better materials, the EMC shielding, a coupling nut that ensures secure connection, and proven embedded hyperboloid contact technology.

Hypertac® Hyperboloid Technology

In particular, the hyperboloid contact technology is a well-known superior performing contact technology for use in demanding environments where reliability and safety are critical. The reliability of the performance is offered by the unique shape of the contact sleeve formed by hyperbolically arranged contact wires, which align themselves elastically as contact lines around the pin, providing a number of linear contact paths. This gives an integrity of signal that other contact technologies can’t deliver. All this enables C series connectors to provide unparalleled immunity to shock, vibration, and environmental impacts to ensure uninterrupted signal integrity.

Hyperboloid Technology

In addition, their design offers a corrosion resistance of 500h to salt spray, a CEI 68-1 category in terms of temperature resistance and a vibration withstanding of 25 to 250 Hz - 5 g following NF F 61-030 Technical Standard. An expert engineer working in the field of safety-critical systems should understand at a first sight that the above-mentioned connectors are ideal to serve devices that must be reliable and precise to provide better train control.

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Conclusion

Train deceleration is a key function that implies passengers’ safety, environment and property protection and nothing can be left to chance or neglected when it is the moment to select the right parts that have to compose the brake system. With this in mind, the design engineers have to pay attention to reduce the overall maintenance costs as well to provide a dependable and market aligned solution.

The way to the right solution is long and will never probably ends as the technological evolution of the rail market follows the continuous flow of the human and science progress. Anyway, a careful and reasoned choice of reliable and durable components is a good start at any time of the human progress, and it can ensure the design engineers to be able to prevent many technical failures that common and not fully reliable components could cause.