Surge protection as part of achieving electromagnetic compatibility
One of the most cost-effective methods for controlling EMI in a system is through the
proper layout of subsystems, and surge protection forms part of this at conducted interfaces.
This can be explained using the following example.
A two-layer shielding topology (geometry) for controlling internal and external
interference sources is shown in Figure 5.3. All the sensitive (critical) circuits are
physically grouped together as far as possible, and are provided with a shield that
prevents fields external to them from having an effect. Similarly, strong internal
sources are grouped together and are provided with a shield that confines the emission
to within the enclosed shield volume. The remaining weak internal sources and
non-critical components are physically grouped together without a special enclosing
shield. All connections from sensitive circuits and strong internal sources are
controlled by interference diverters, such as filters, surge protectors and equipotential
bonds. All the subsystems are surrounded by an external shield that excludes
external electromagnetic disturbance (e.g. lightning). All the connections penetrating
the external shield (e.g. power, data, telephone, pipeline) are provided with
interference diverters.