What are the defining trends in the design of electrical enclosures? And are the markets for them changing? James Hunt looks at how enclosures for electrical contractors are evolving:
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| Top - the new Marina enclosure by Legrand; centre - Rittal's 304 |
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Some electrical enclosure trends are not always obvious. For example, just about every electrical contractor will be aware of the IP codes for water/dust ingress protection. But have they heard of IP69K? Commented Rittal's John Wilkins: "One thing rearing its ugly head is the increasing need for enclosures to meet IP69K degree of protection. What's the 'K' for? This is DIN 40 050-9/5.93 and is for protection against steam cleaning. There has been increasing demand for equipment to be steam cleaned."
"Another trend", continued Wilkins, is that, with less pure electrical work than there used to be, more and more electrical contractors are doing structured cabling work. More such enclosures are therefore required today."
This point was echoed by Sarel's Brian O'Donohue who said: "We've also seen an upsurge in contractors getting involved in structured cabling solutions - there's now a big demand for 19 inch racks."
Central computer rooms are becoming ever more important with IT equipment being protected by server cabinets. One related issue, highlighted by APW, is that of server racks mounted directly on floor tiles. Cutting expensive tiles is time consuming and messy, so APW's solution is a special plinth that replaces the tiles. This neat solution is quick to install and allows good cooling air control from the raised floor. APW also cites increasing power requirements deriving from the need to fit ever more servers into racks. Rack manufacturers are therefore providing integral power distribution equipment. Also, deeper server racks are reducing corridor width, so double access doors are becoming commonplace, single doors being too wide to be opened.
Noting that an enclosure is only as good as its ability to protect its contents, O'Donohue said: "We are seeing an upturn in demand for glass reinforced polyester (GRP) enclosures in the UK. We welcome this development. European sales have been significant for years but conservative UK has been very slow to take them up, until now. This upturn has been prompted by concerns about corrosion. There's another benefit - working GRP doesn't produce conductive / magnetic swarf."
However, while GRP provides good strength, rigidity and resistance to chemicals, reinforcing fibres can rise to the surface with wear, weakening the structure. To solve this problem, ABB has introduced its Gemini co-injection-moulded switchboard with the same benefits as GRP enclosures, but none of the disadvantages.
The migration of indoor enclosures to outdoors is now well under way. There, an enclosure can only provide long life if built of good materials - such as GRP - or 3CR12 by Cromweld Steels. This is a12% chromium containing ferritic stainless steel with a proven track record as a material of choice for enclosure manufacturers worldwide. Enclosures made from this have outlasted traditional coated steel boxes by over a decade.
The days when enclosed equipment was expected to perform in all temperatures and humidity without internal climate control are long gone. One manufacturer supplying climate control equipment is Axair Fans whose new range of PTC anti-condensation heaters (45 - 150W), provide efficient heat dissipation in compact, lightweight units. Control is from -10 to +80ºC. In the same vein, Sarel's Clima free software package allows easy enclosure thermal management calculations.
One of the many issues affecting modern enclosure design is the ATEX 100a Directive applying to equipment used in potentially explosive atmospheres (Zones 1 and 2 hazardous areas). Rittal is one of several companies that have successfully tested their enclosures to meet it and its KEL product range is now certified to ATEX 100a.
One trend is unwelcome. Rolla's Roger Greenwood said: "A negative development is the demise of the UK short-circuit testing laboratory. Although we sell most of our enclosures to panel builders, many of our completed enclosures are installed into large buildings. That's why we've always insisted on proper testing. We are very concerned as the last of the UK facilities, the British Short Circuit Testing Station (BSTS), has also just closed its short-circuit testing lab. It's very sad. So now, any UK manufacturer will have to go abroad to test which will add cost - ultimately to the detriment of the end-user."
Some enclosure products
Rittal's latest grade 304 stainless steel KL enclosures meet IP69K for pressure washer ingress protection and are ideal for food industry, wastewater treatment plant and other applications. For control-orientated use, Rittal's new IP65 Bus Enclosure allows cables and connectors of differing diameters to be easily brought into (for example) field bus system enclosures. Modular plates facilitate individual cable entry.
The new Eldon Electric AFS IP66 (Nema 4X) 304 grade stainless steel wall- or machine-mounted enclosure has been designed especially for wet environments. An integral overhanging sloping roof ensures that liquids are diverted away from the door. It is therefore ideal for hose down processing and food industry operations. It can act as a 'mini console'.
Legrand Electric's wall-mounting or freestanding Atlantic, Marina and Altis enclosures allow user requirements to be fully met. Looking at the enhanced Atlantic range, these polyester powder coated MS enclosures are also available in 304L grade stainless steel with IP66 - IK10 protection for food industry applications. 316L grade stainless steel versions can be supplied. There is also a higher EMC protection option.
For server security, the new modular Schroff server cabinets, based upon the PROLINE platform, meet international standards and comprise a welded steel frame with a static load bearing capacity to 600 kg (also valid for 19" planes). Perforated doors allow a very high air throughput. In addition, there are the competitively priced PROLINE NET and PROLINE NET Comfort distribution cabinets.
Competitively priced enclosures for every telecomms application are now available from Sarel. The range now includes both steel and GRP metering cabinets, small rack-type enclosures for small office/home office applications, 19" rack enclosures (accessible from all sides), and floor-standing networking racks from 24U to 47U. Also available are fully equipped power distribution racks / server co-location enclosures for data centres.
The new, multi-functional and competitively priced Image 620 global enclosure platform from APW Enclosure Solutions is ideal for networking, broadcast, electronics and security environments. This enclosure comes in a wide range of sizes, and can act as a server rack to house the deepest servers available. Ready assembled or flat-packed, the Image 620 gives networking installers a high cable management capability.
Primarily a major panel builder, Main Systems also manufactures several standard enclosure ranges. These embrace general electrical applications, plus designs suitable for those electrical contractors who are into panel building. Made from high quality electro zinc-coated mild steel, all structures are vapour de-greased and then coated with 60-80 microns of thermally-cured, polyester-based powder paint.
MCC Technique's all-new distribution board / enclosure has been designed to look attractive and uses the latest metalworking technologies for big cost savings. Modularity derives from simple frames for cableways, compartments and bus bar chambers. This product has been designed around all the major switchgear manufacturers' products and can include all necessary copper work. The company type tests for safety.
Rolla supplies fixed and withdrawable Form 4 type-tested enclosures and bus bar systems. Motor control centre (MCC) and LV switchboard suites can be equipped with bus bar systems rated 26 to 80kA for 1 or 3s, 630 to 6300A. Rolla enclosures have been impact tested BSEN 50102: 1995. A 'no wire' earthing facility on all external covers cuts wiring time and makes on-site maintenance access quicker and safer.
This article was originally published in Electrical Times magazine by Highbury Business Communications - a Voltimum UK Media Partner.
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