Environmental Engineering Reference
In-Depth Information
Electromagnetic field
(EMF)
Electric field
(E)
Magnetic field
(B)
Induced electrical field
(iE)
FIGURE 7.10
Simplified view of the fields associated with submarine power cables. (Adapted
from Gill, A.B. et al.,
COWRIE 1.5 Electromagnetic Fields Review: The Potential Effects
of Electromagnetic Fields Generated by Sub-Sea Power Cables Associated with Offshore
Wind Farm Developments on Electrically and Magnetically Sensitive Marine Organisms—A
Review
, COWRIE-EM Field 2-06-2004, Cranfield University, Cranfield, U.K., 2005.)
When electricity flows (electron flow) through the wire in a cable, every section
of the wire has this field of force around it in a plane perpendicular to the wire,
as shown in Figure 7.11. The strength of the magnetic field around a wire (cable)
carrying a current depends on the current, because it is the current that produces
the field. The greater the current flow in a wire, the greater the strength of the
magnetic field. A large current will produce many lines of force extending far from
the wire, whereas a small current will produce only a few lines close to the wire,
as shown in
Fig u r e 7.12
.
Circular lines of force
Current
Side view
FIGURE 7.11
Circular fields of force around a wire carrying a current are in planes perpen-
dicular to the wire.
