Freedom of component choice creates successful designs

Paul Boughton

Most design engineers have probably faced the dilemma of having to use one or more components that don’t quite fit the bill. Inevitably the result is a final design that is not completely satisfactory. Mark Severn says that electrical enclosures should not be an afterthought, but carefully selected from a wide range of options

An electrical enclosure serves two functions: to contain and protect the electrical equipment used in a system and to create the visual appearance of the system. Most design engineers would probably say that the first function was by far the more important, although sales engineers, end-users and resellers may disagree.

The options for sourcing an enclosure are to either build your own (only suitable for one-off systems – and not all of those); work with an enclosure manufacturer to develop a bespoke design (for long-run production); or buy a standard unit (the most common option).

Good enclosure manufacturers understand that they have to offer a very wide range of products in order to meet all the demands of their diverse user group. Their range is likely to embrace handheld devices, desktop equipment, industrial control cabinets, IT racks and hardened products for demanding applications; and these should be offered in numerous sizes.

A traditional enclosure is pretty much a rectangular box. This is a very efficient shape in terms of interior volume and access, but a comprehensive product range also needs to address other criteria. For instance, there is a trend towards smaller systems, so a good range will include some unusual shapes which have the potential to fit into tight spaces. Another trend is towards handheld, so ergonomic enclosures become attractive. If a mobile device or static system is likely to be subjected to rough treatment, an extra robust design may also be useful.

Desktop enclosures will typically have to include an aesthetic appeal. One way to achieve this is with a custom solution, but this is expensive and will have lead time implications. A well thought out range of standard desktop solutions should be able to accommodate the majority of industry requirements, and include some customisable options such as retractable feet, inlay panels and colour choices.

While the external dimensions of an enclosure are important, it is the internal design that ultimately determines suitability for a given application. For instance, there may be a requirement to fix a terminal block in place or to securely mount a PCB (printed circuit board). Battery powered applications may also require separate compartments.

Having spent many years working with OEMs to develop solutions for applications across many industries, the Retex enclosure range is able to offer internal ‘maps’ for each of its product series, which means that a great variety of designs can be accommodated within the product range. Options include PCB mounts integrated into the internal enclosure wall - which allow the card to simply slide into place - and separate battery compartments.

From the above we see that an enclosure is far more than just a box. Therefore, the best way to ensure the right solution is to find a manufacturer that can act as a specification partner, rather than simply a supplier. Speak to them about your design and ask how different products in their range might suit your needs. While customisation is a fantastic way of tweaking a design to your needs, finding a standard product that closely matches them in the first place will save you time and money further down the line.

The Retex range from Hylec-APL offers one of the most comprehensive ranges of electrical enclosures on the market. For instance, its hand-held enclosures include options for EMI/RFI shielding and a wide breadth of customisation options.

Series 31 is a small, robust enclosure with bevelled and round edges to make it comfortable to carry in your hand or your pocket; an IP65 neoprene gasket joint is optional. Series 32 and Series 33 enclosures feature gently curved edges for improved ergonomics when held in the hand. Their snap-fit design speeds up installation. Series 33 adds rubberised corners, while Series 40 has a compartmented interior. Finally, Series 68 is constructed from aluminium and screws shut for added security.

Mark Severn is with Retex UK, Wellingborough, Northants, UK.