By Simone Bruckner, Managing Director, Cressall Resistors
When refining product design, the manufacturer, purchaser and end user will all approach equipment requirements from different perspectives. While the manufacturer may be more concerned with keeping production costs low, the end user will be more interested in usability and functionality of the final product.
For many industries, the product development process follows four key steps: concept initialisation, research and development, design prototyping and full-scale production. During the research stage, the right questions must be asked to ensure the product is fit for purpose. When designing an enclosure for electrical equipment, this research is usually undertaken when the customer provides an initial specification.
The specification writer may not be aware of all criteria that impacts the enclosure’s design therefore it is the enclosure supplier’s responsibility to ask those key questions to establish a comprehensive brief.
One of the most important considerations when designing an enclosure is the environment it will be operating in, since each industry presents slightly different working conditions.
Selecting the correct material for the enclosure is an important consideration. For many enclosures, the preferred material is 316L stainless steel, which offers good long-term corrosion resistance; however, there are enclosures made from other grades of stainless steel, such as 304 as well as pre-galvanised steel and hot-dip galvanised steel.
In addition, further mechanical considerations exist depending on the installation location of the equipment such as wind loading, ice loading and seismic shock. Where these apply, the enclosure maker uses tools such as CFD (Computational Fluid Dynamics) and FEA (Finite Element Analysis) to assess the proposed design for the geographical parameters, accelerating the design process.
Level of protection
While the enclosure’s material protects the majority of its contents, in environments such as marine vessels, ingress protection is vital in stopping dust, moisture and other contaminants from affecting the resistor. The BS EN 60529 standard provides quantified levels of protection for people and equipment from the outside environment. These levels are described by an IP (ingress protection) code number designating protection from liquids and solids.
However, this is where the equipment manufacturer can assist the customer who may not understand the full impact that placing a high IP level requirement can have for the enclosure manufacturer. Higher levels place tighter restrictions on openings in the enclosure panel work, which can restrict ventilation. Therefore, with a thorough understanding of the equipment, the designer can propose a suitable level to meet all requirements.
Fabrication, assembly and installation
Many manufacturers design and build products at a central location, from where the assembled equipment is shipped to the end user.
Enclosures can be large, especially in high voltage applications where air gap clearances are high. The designer must carefully consider how the enclosure will be fabricated, assembled, shipped and installed to ensure a cost-effective solution is delivered.
Once the enclosure has arrived at its destination, it needs to be installed: ground level or at an elevated position. Consideration must be given to how the enclosure should be lifted into position, for example by lifting eyes or beams or with forklift channels.
The path to design success
The design and build of an enclosure is not a one-way conversation. As is so often the case, communication in the design phase is critical to future success. While the chosen manufacturer may have the experience to make recommendations and assumptions, the client must also input into the design process.
Communication between all relevant parties coupled with a considered design approach will ensure the electrical enclosure design. If the enclosure maker has a highly-skilled in-house design team – like at Cressall – to use its experience together with 3D design and simulation techniques this will achieve optimised solutions.