Samuel James is a manufacturer and supplier of points heating systems for the UK rail network, and help to ensure that in cold weather, Britain’s travel infrastructure doesn’t freeze.
The company’s design engineer, Chris Wall, explains why he believes that a move away from metallic enclosures at track side is vital.
When designing any external electrical application, one of the first and most vital considerations is the choice of enclosure. Apart from the obvious considerations, such as its level of ingress protection and how it will stand-up to the massively varying temperatures that will be experienced, it is important to think about the location of the product and any possible hazards that it may face during its lifespan. In the rail industry there are many of these hazards that spring to mind.
Life by the trackside can be very tough. Fumes and brake dust can be incredibly abrasive and debris is often sent flying at extremely high speeds. All Samuel James products are delivered with a 25 year lifespan guaranteed, so it is vital to be sure that the enclosures in which they are housed will not corrode or weaken in the harsh environment. With the proposed investment in electrification which is coming into effect across the UK it is also important to consider the danger of electrocution to maintenance workers.
Samuel James’ points heating systems are installed at thousands of railway junctions across the UK. Each system consists of a large control unit which is designed to constantly monitor and maintain the temperatures of multiple points at a pre-determined, optimum temperature.
Connected to these control units are approximately four or five smaller units, located by the track, which each provide the information for an individual set of points. These units include external temperature probes which require a further, smaller, trackside enclosure.
With each installation featuring ten or more enclosures placed right by the trackside, a lot of time is spent considering options to guarantee that 25 year promise. Increasingly this has led to a move away from the traditional metallic enclosures - which are prone to corrosion, denting and are highly conductive - to non-metallic alternatives. Samuel James now exclusively use the Spelsberg range of glass reinforced polyester (GRP) enclosures for trackside installations and the polycarbonate TG range to house the temperature probes.
Spelsberg’s heavy duty GRP enclosures provide effective corrosion resistance for electrical and electronic controls in the harsh and abrasive environments found trackside. The material offers a high level of rigidity at minimal thickness meaning that maximum internal space is provided for installation while protection from external impacts - such as stone chippings - is assured.
Having subjected the enclosures to rigorous testing, it was found that the tough GRP and polycarbonate construction provides improved protection against knocks when compared with traditional metal enclosures. In addition, they provide IP68 protection, are resistant to the corrosive effect of brake dust, fumes and the weather, and provide electrical insulation - in turn improving safety for maintenance crews.
Doors can be left or right mounted and the hinging allows door opening to up to 240° for easy access into the enclosures. An integral drip shield directs liquids away from the door shield in external environments and options include key locks for security and a stylised window door which provides easy visual inspection of interior components.
CNC machining of plastic enclosures is readily available and all enclosures are received fully assembled with entry points pre-drilled and fitted with hinged lids to improve access once on-site.
Together with the ability to customise designs, this means that installers simply need to mount three or four terminals and they are finished, which reduces trackside installation times significantly. With sponsorship from its customers, Samuel James expects to receive PADS (Parts and Drawings Systems) approval for the new enclosures which will allow their use for all future projects.
Working trackside will always be a dangerous place for maintenance crews and a harsh environment for equipment. As manufacturers, Samuel James has a responsibility to ensure that all components prevent further hazards from being introduced whilst simplifying the work that needs to be undertaken. Having found that plastic enclosures provide significant benefits to the protection and longevity of trackside electronics, it is now committed to investing in this technology and providing complete electrical insulation at every stage on all systems.