Westbay EMC Assistant
Software Guidance in Enclosure Design for EMC
The Westbay EMC Assistant provides a computer based guide to
aspects of electronic equipment enclosure design which can affect
electromagnetic compatibility (emc).
The design of an enclosure for an item of electronic or electrical equipment can have a dramatic effect on electromagnetic field emissions from the equipment, or the susceptibility of the circuitry to external fields.
For example, the detail of the interface between a removable access panel and the enclosure wall affects the leakage of fields at that point. If the interface is solid (welded for example), no leakage occurs, as would be expected. However, if the panel is held in place by fixing screws, the gaps between the fixing screws behave as apertures, allowing field leakage to occur.
The mechanical designer needs an understanding of the basics of emc, to be able to modify the design appropriately if an emc problem occurs. In the interface example, the enclosure designer has to be aware that reducing the distance between the fasteners will reduce the leakage at a particular frequency, but also that electrical contact must be made at each fastener between the panel and the enclosure, otherwise there will be no shielding from the panel at all!
Westbay EMC Assistant sets out to provide the mechanical designer with those emc basics that will affect emc performance through the enclosure design. It does this in an easy to access way, without the need either to attend an external course, or to read some over-complicated text book.
An extract from the section which describes emc and interfaces.The diagram is explaining the importance of the placement of a fastener relative to the position of a conductive emc gasket. The bolt has been incorrectly placed between the gasket and the interior. This creates a leakage path down the bolt clearance hole. The fastener should be placed between the gasket and the outside of the enclosure wall.
An extract from a screen page describing how openings, or apertures, in the enclosure can be shielded. This diagram shows the basic layout of a honeycomb mesh panel, used to provide both shielding and cooling air flow.
An extract from a page describing how an electrostatic discharge (ESD) can be passed to a circuit board, where it can damage electronic components. Openings in a plastic front panel, even though they appear to be closed by a knob for example, provide a conduit for the discharge.
The ESD section explains how to route the discharge to ground, and also how to tackle secondary problems which occur when two equipments are interconnected.
The EMC Assistant consists of 113 screens of information, containing simple diagrams with explanatory text. The screens can be viewed in sequence, as a course, or can be used separately as a reference. Basic theory is mixed with practical examples of emc practice wherever possible.
A Contents facility allows any screen to be accessed, whilst a Search facility uses key words attached to each screen page to find a particular topic. A description of each page found is provided, to help the user decide if the required information has been found.
The 113 screens are divided into the following topics:
The EMC Assistant uses simple captions to explain a particular topic. Several captions are often provided per page, explaining several diagrams. Delayed appearance of captions or diagrams is used sometimes, to emphasise some feature or other.
Windows 95or later. Screen resolution: 800 x 600 (Not suitable for
VGA 640 x 480 displays)
Westbay Technology Ltd, Main Street, Baycliff, Ulverston, Cumbria LA12 9RN, England
Tel: 01229 869 798 (from the United Kingdom) Tel: +44 1229 869 798 (International) Contact by e-mail