• • • RAIL INDUSTRY • • •
An air conditioner can only be operated on a closed, waterproof electronic cabinet.
Protection against environmental influences Outdoor use exposes electronic systems to extreme conditions such as temperature fluctuations from 30 to 80°C, high humidity as well as rain, snow, hail, ice, intense solar radiation, lightning strikes, fire, storms, rockfall, dirt such as sand and dust, and electromagnetic radiation. Passing trains cause sudden differences in air pressure as well as vibrations and shocks which should not be underestimated. Depending on the speed, enormous pressure forces can develop due to the fluctuations in air pressure and affect the cabinet. For outdoor cabinets to withstand these mechanical influences, aspects like reinforcements on the cabinet rack must be taken into account in the design. In particular, protection against shock and vibration must be ensured at a distance of 1 to 3 m from the track. For this purpose, an outdoor cabinet must be certified according to EN 50125-3. In addition, an earthquake resistance up to Bellcore Zone 4, which corresponds to a magnitude of over 6 on the Richter scale, is of great importance, depending on the installation site. Wind resistance with values from 180 km/h up
to 250 km/h, which corresponds to a Category 4 hurricane, must also be guaranteed by the structure of the cabinet. A weather resistant powder coating or an anti-graffiti coating is typical to protect the cladding parts from mechanical damage. Protection against unwanted electromagnetic
radiation on sensitive electronics also plays a central role in railway systems. The environment must be protected from emitted radiation, while the electronic systems must be protected from penetrating radiation. Appropriate measures for grounding and lightning protection are also necessary
Security and anti-intrusion
protection In freely accessible outdoor applications, there is also the risk of vandalism and unauthorised access. Therefore, a high degree of robustness and stability are standard features of outdoor cabinets. A stable cabinet frame and a double- walled design with modified wall thicknesses are effective measures when it comes to security and anti-burglary protection. It is also important that handles are protected against vandalism, and that screws for removing the roof, side walls, and base panels are only accessible from the inside, making access to the interior of the cabinet considerably more difficult for unauthorized persons.
Scalability and flexibility For different areas within rail applications, it is crucial that outdoor cabinets are available in different sizes. Ideally, the cabinets are designed to be scalable in height, width, and depth, and can be easily adapted to the desired applications and future proofed. An extensive range of accessories with elements for interior installation, cable routing, and cable entry, is also helpful and ensures a high degree of flexibility. Easy access to the inside of the cabinet from all sides is important for performing maintenance as well as mounting and installing electronics within the cabinet. The flexibility of Modular Outdoor Cabinets is supported by the scalability of the cabinet design and a wide range of compatible 19in accessories.
Summary Customers’ requirements for cabinets often include the integration of additional components such as display elements, monitoring, cabling, or power supplies. These components can either be supplied by the customers or purchased and assembled via the cabinet supplier according to the specifications submitted. Outdoor cabinets containing a suitably configured air conditioning system to cool built in electronics guarantee reliability and durability for railway applications. In addition to certified protection against environmental influences and vandalism, the flexibility and scalability of the cabinet is necessary to set up a solution modified to the customer’s application. The nVent SCHROFF Modular Outdoor Cabinet range available from Foremost Electronics offers all the necessary features in this respect. This cabinet range has been tested and certified for all relevant railway applications on the trackside and thus offers safety and reliability for the proper functioning of the application over a long service life.
electricalengineeringmagazine.co.uk
ELECTRICAL ENGINEERING • MARCH 2022 27
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