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The Westbay EMC Assistant
provides a computer based guide to aspects of electronic equipment
enclosure design which can affect electromagnetic compatibility (EMC).
It is tailored to the needs of mechanical designers, and does not
assume any prior EMC knowledge.
Overview
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. |
A Division of EMC Resources 
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.
